We were discussing sound cards and I was reject= ing=20 this as impractical for seismic purposes. The data files are massive and I=20 haven't found a way of using the 24 bit soundcard ADC for 20 sps sampling.

Chuck a bit of cash at it and get rid of the yo= ur=20 problems? Larry sells a fairly good 8 channel serial board, which you can us= e=20 with a GPS receiver.

If you want to play, fine. If you want to work,= get=20 rid of problems that you do not need to have.

Just what rate of water rise do you get al= ong=20 the Red river?? Even for marine waves, 20 sps is adequate and most geologica= l=20 systems will go to 100sps, some even more.

>> A GPS will give you the best time s= tamp=20 you could ask for some even have a 100 kHz clock as well a 1 second pulse th= at=20 are linked to GPS clocks. They can be used to phase lock frequency sources t= o=20 for super accurate osillators.

I am NOT asking for the best system, just one t= hat=20 relatively inexpensive, low power and ADEQUATE for my purposes.

I use VLF timing signals. You can get relativel= y=20 inexpensive receiver boards with a ferrite aerial: or gut a radio clock. You= get=20 about 10 mS + the transit time. The only folks who need it more accurate mon= itor=20 volcanoes of do reflection seismometry. I have been all along this road. I w= ould=20 be great if Larry would fit the software to decode WWVB directly, but he=20 seems concentrate on GPS. GPS is power hungry and needs a clear l= ine=20 of sight to satellites; 60 KHz VLF radio is low power and can be used most=20 anywere. I can use it where I can't get MW radio, even underground. Just kee= p it=20 away from striplights, radio transmitters, TVs and computer monitors. I have= =20 used it underground near radio and TV transmitters - find a nice hole and bu= ry=20 it to screen it! It is no accident that submarine communications use=20 the VLF range of frequencies.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 are not interested in 1 to 20 Hz signals sound cards are pretty good tools= .. If=20 you are really serious about low frequencies and accurate timing Windows p= oses=20 a lot of problems.

0 to 10 Hz is my range of interest. I want abou= t=20 +/-0.1 sec accuracy, 24 hrs / day. This is why I use an ADC which has it's o= wn=20 on board timing and correction. The data goes to the hard disk with a time s= tamp=20 regardless of the rubbish timing on the operating system.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>First=20 Windows is an event driven operating system and there is no assurance when= a=20 program will run. The sound card gets around that but you have to put a ch= irp=20 on the signal to synchronize it with time you can depend on the computer c= lock=20 or the RS232 port.

Can you say that again please? I don't quite=20 understand.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Having=20 worked with embedded systems for the last 20 years I would choose a real t= ime=20 computer. There are real time versions of Linux but I think that's over ki= ll=20 for dataloging geophones.

You have the real and the software clocks on=20 computer boards. You used to be able to get 4.194 MHz AT crystal clocks on=20 computers, which could be made moderately reliable. All the boards that I ha= ve=20 seen recently use 32 KHz crystals which appear to be rejects from clock=20 manufacturers. A random error of 20 sec to 2 min a day is what I call utter=20 ****. If you had a quartz watch which was that bad, you would take it back t= o=20 the shop and demand your money back.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>A GPS=20 for a time base, a good a/d converter and fast microcontroler would be the= way=20 I would do it. I am working with a very fast board 60 MHz with 4 10 bit A/= D=20 channels

Does 10 bits give you enough resolution, taking= =20 into account sensor noise? The Dataq $25 starter ADCs give you 4 Channels at= 240=20 sps total - 60 sps / channel.

I can't figure out at the moment why you wo= uld=20 need a high monitoring rate for looking at water levels?

Regards,

Chris Chapman

Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 01:03:18 -0500 ChrisAtUpw@....... wrote: > In a message dated 20/07/2005, gcouger@.......... writes: > > Chris, > > Out of sequence and possible not on subject but it has some thoughts > on timing that are important. I must have come in the middle and > don't understand your set up. I thought you were recording data to > disk with a computer sound card. > > I am working on a seismometer that records several seismometers at > one time in the 0-50 HZ range on the two channels of a sound card > for imaging shallow aquifers looking for larger gravel to find > better water well in a shallow aquifer along Red River > between Oklahoma and Texas so I can afford to put in irrigation. > > I have probably imposed my project on yours without realizing it. > > Hi Gordon, > > We were discussing sound cards and I was rejecting this as > impractical for seismic purposes. The data files are massive and I > haven't found a way of using the 24 bit soundcard ADC for 20 sps sampling. > > Chuck a bit of cash at it and get rid of the your problems? Larry > sells a fairly good 8 channel serial board, which you can use with a GPS > receiver. > If you want to play, fine. If you want to work, get rid of problems > that you do not need to have. > Just what rate of water rise do you get along the Red river?? Even > for marine waves, 20 sps is adequate and most geological systems will go > to 100sps, some even more. > > >> A GPS will give you the best time stamp you could ask for some > even have a 100 kHz clock as well a 1 second pulse that are linked to > GPS clocks. They can be used to phase lock frequency sources to for > super accurate osillators. > > I am NOT asking for the best system, just one that relatively > inexpensive, low power and ADEQUATE for my purposes. > I use VLF timing signals. You can get relatively inexpensive > receiver boards with a ferrite aerial: or gut a radio clock. You get > about 10 mS + the transit time. The only folks who need it more accurate > monitor volcanoes of do reflection seismometry. I have been all along > this road. I would be great if Larry would fit the software to decode > WWVB directly, but he seems concentrate on GPS. GPS is power hungry and > needs a clear line of sight to satellites; 60 KHz VLF radio is low power > and can be used most anywere. I can use it where I can't get MW radio, > even underground. Just keep it away from striplights, radio > transmitters, TVs and computer monitors. I have used it underground near > radio and TV transmitters - find a nice hole and bury it to screen it! > It is no accident that submarine communications use the VLF range of > frequencies. > > If you are not interested in 1 to 20 Hz signals sound cards are > pretty good tools. If you are really serious about low frequencies > and accurate timing Windows poses a lot of problems. > > 0 to 10 Hz is my range of interest. I want about +/-0.1 sec > accuracy, 24 hrs / day. This is why I use an ADC which has it's own on > board timing and correction. The data goes to the hard disk with a time > stamp regardless of the rubbish timing on the operating system. > > First Windows is an event driven operating system and there is no > assurance when a program will run. The sound card gets around that > but you have to put a chirp on the signal to synchronize it with > time you can depend on the computer clock or the RS232 port. > > Can you say that again please? I don't quite understand. > > Having worked with embedded systems for the last 20 years I would > choose a real time computer. There are real time versions of Linux > but I think that's over kill for dataloging geophones. > > You have the real and the software clocks on computer boards. You > used to be able to get 4.194 MHz AT crystal clocks on computers, which > could be made moderately reliable. All the boards that I have seen > recently use 32 KHz crystals which appear to be rejects from clock > manufacturers. A random error of 20 sec to 2 min a day is what I call > utter ****. If you had a quartz watch which was that bad, you would take > it back to the shop and demand your money back. > > A GPS for a time base, a good a/d converter and fast microcontroler > would be the way I would do it. I am working with a very fast board > 60 MHz with 4 10 bit A/D channels > > Does 10 bits give you enough resolution, taking into account sensor > noise? The Dataq $25 starter ADCs give you 4 Channels at 240 sps total - > 60 sps / channel. > I can't figure out at the moment why you would need a high > monitoring rate for looking at water levels? > > Regards, > > Chris Chapman > Chris, I am not looking for water levels I putting out sensors and making a shock moving over and making another shock ...... and another shock and resetting the sensors and doing it over again to do a seismic study of the aquifer of the water bearing sand and 30 feet down. I need a post process GPS signal to know where I am I might as well use the time spruce on it. Almost everything I work with has a GPS. I did the first vehicle units for www.ipsolutionsinc.com and all the software for spryer in http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852568F10056A8F7/$file/97-4p15.pdf!open I agree they are power hogs and take a lot of resources for time for seismic senors that VLF will do just as well as GPS. I have seen jitter on VLF from WWV in a really bad magnetic storm but not as often as I have lost lock with the GPS. If you want to time sync a signal on a sound card you can depend on windows for time. It is too uncertain when the windows routine will time stamp it. Windows can't be made work in real time. If you want to record 0 to 20 Hz signals on a sound card a mixer and local oscillator at 500 Hz will move the 0 to 20 Hz to 500 to 520 and the inverse of it to 480 to 500. You can use DSP to get the signal back from either one. Ten bits is enough for most situations in vehicles any more is lost in the noise of the vehicle. In the case of seismometer in an open field a more sensitive A/D could be used. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 08:33:42 EDT In a message dated 21/07/2005, gcouger@.......... writes: Chris, I am not looking for water levels I putting out sensors and making a shock moving over and making another shock ....I need a post process GPS signal to know where I am I might as well use the time spruce on it. Hi Gordon, I understand now. We used chains of hf geophones and a pneumatic hammer.... Sure you need te position accurately as well. Do you use relative GPS to give you accuracies down to a few cm? Almost everything I work with has a GPS. I did the first vehicle units for www.ipsolutionsinc.com and all the software for spryer in http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852568F1005 6A8F7/$file/97-4p15.pdf!open Interesting, but availablily depends on the roots being able to find nutrients and hence on the rainfall & intensity. It probably would not work too well for things like moss and poor land grasses. The grab every nutrient molecule going and store them. This was the problem in Finland after the Chernobyl nuclear disaster. The grasses and moss which fed the reindeer heards soaked up most of the radioactivity. I agree they are power hogs and take a lot of resources for time for seismic senors that VLF will do just as well as GPS. I have seen jitter on VLF from WWV in a really bad magnetic storm but not as often as I have lost lock with the GPS. I don't get this problem at all often. The computer looks for an interference free minute every half hour and then adjusts the precision crystal oscillator offset on the 59 mean pulses. The drift is initially set at less than 5 ppm and can be maintained down parts in 10^8 If you want to time sync a signal on a sound card you can depend on windows for time. It is too uncertain when the windows routine will time stamp it. Windows can't be made work in real time. Where are you getting your time stamp from? I definitely can't rely on either the software or the hardware clocks on the board. If you want to record 0 to 20 Hz signals on a sound card a mixer and local oscillator at 500 Hz will move the 0 to 20 Hz to 500 to 520 and the inverse of it to 480 to 500. You can use DSP to get the signal back from either one. Ten bits is enough for most situations in vehicles any more is lost in the noise of the vehicle. In the case of seismometer in an open field a more sensitive A/D could be used. Regards, Chris Chapman

In a message dated 21/07/2005, gcouger@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Chris,

I am not looking for water levels I putting out sen= sors=20 and making a shock moving over and making another shock ....I need a post=20 process GPS signal to know where
I am I might as well use the time spr= uce=20 on it.

Hi Gordon,

I understand now. We used chains of hf geophone= s=20 and a pneumatic hammer.... Sure you need te position accurately as well. Do=20= you=20 use relative GPS to give you accuracies down to a few cm?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Almost=20 everything I work with has a GPS. I did the first vehicle units for=20 www.ipsolutionsinc.com and all the software for spryer in=20
http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852= 568F10056A8F7/$file/97-4p15.pdf!open

Interesting, but availablily depends on the roo= ts=20 being able to find nutrients and hence on the rainfall & intensity. It=20 probably would not work too well for things like moss and poor land grasses.= The=20 grab every nutrient molecule going and store them. This was the problem in=20 Finland after the Chernobyl nuclear disaster. The grasses and moss which fed= the=20 reindeer heards soaked up most of the radioactivity.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I agree=20 they are power hogs and take a lot of resources for time
for seismic=20 senors that VLF will do just as well as GPS. I have
seen jitter on VLF= =20 from WWV in a really bad magnetic storm but
not as often as I have los= t=20 lock with the GPS.

I don't get this problem at all often. The comp= uter=20 looks for an interference free minute every half hour and then adjusts the=20 precision crystal oscillator offset on the 59 mean pulses. The drift is=20 initially set at less than 5 ppm and can be maintained down parts in 10^8 <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 want to time sync a signal on a sound card you can depend
on windows f= or=20 time. It is too uncertain when the windows
routine will time stamp it.= =20 Windows can't be made work in real time.

Where are you getting your time stamp from? = I=20 definitely can't rely on either the software or the hardware clocks on the=20 board.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If you=20 want to record 0 to 20 Hz signals on a sound card a mixer and local oscill= ator=20 at 500 Hz will move the 0 to 20 Hz to 500 to 520 and the inverse of it to=20= 480=20 to 500. You can use DSP to get the signal back from either one.

Ten= =20 bits is enough for most situations in vehicles any more is lost in the noi= se=20 of the vehicle. In the case of seismometer in an open field a more sensiti= ve=20 A/D could be used.

Regards,

Chris Chapman

Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 05:48:51 -0700 Snip I am not looking for water levels I putting out sensors and making a shock moving over and making another shock ...... and another shock and resetting the sensors and doing it over again to do a seismic study of the aquifer of the water bearing sand and 30 feet down. I need a post process GPS signal to know where I am I might as well use the time spruce on it. UnSnip This is not earthquake recording, this is exploration seismic. The frequencies you care about will be between 10 and 500 Hz and a perfectly normal sound card will handle these signals. You may need some preamps like you would with a dynamic phonograph cartridge, because the signals from geophones are small. You will need zero time from your shock source (a sledge hammer should be adequate). The best choice is a small, cheap crystal phonograph cartridge taped near the head connected to the second channel. You don't care about absolute time, just time relative to the impact, so forget GPS timing. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 10:06:54 EDT In a message dated 21/07/2005, dcrice@............ writes: This is not earthquake recording, this is exploration seismic. You will need zero time from your shock source (a sledge hammer should be adequate). The best choice is a small, cheap crystal phonograph cartridge taped near the head connected to the second channel. You don't care about absolute time, just time relative to the impact, so forget GPS timing. I have used ordinary 13 mm piezo disks for the hammer sensor, but you do need some sort of voltage limitation to prevent input amplifier protection. The 'glass break' sensors sold for window protection work fine and are maybe less than 1/10 the price of a phono cartridge. You can use biassed current differencing amplifiers to give a ramped gain / time relationship to maintain the reflected signal strength. Regards, Chris Chapman

In a message dated 21/07/2005, dcrice@............ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>This is=20 not earthquake recording, this is exploration seismic.
You will n= eed=20 zero time from your shock source (a sledge hammer should be
adequate).=20= The=20 best choice is a small, cheap crystal phonograph cartridge
taped near t= he=20 head connected to the second channel. You don't care about
absolute tim= e,=20 just time relative to the impact, so forget GPS=20 timing.

I have used ordinary 13 mm piezo disks for the=20 hammer sensor, but you do need some sort of voltage limitation to=20 prevent input amplifier protection. The 'glass break' sensors sold= for=20 window protection work fine and are maybe less than 1/10 the price of a= =20 phono cartridge. You can use biassed current differencing amplifiers to give= a=20 ramped gain / time relationship to maintain the reflected signal strength.

Regards,

Chris Chapman

Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 13:21:01 -0500 Hi Chris, > > I understand now. We used chains of hf geophones and a pneumatic > hammer.... Sure you need te position accurately as well. Do you use > relative GPS to give you accuracies down to a few cm? I haven't so far. The precision of the seismic data is not that good. But I will leave temporary bench marks I can find. Since it is being farmed no till I can bury a piece of tinfoil and put up a PVC post. If the post gets knocked down a GPS and metal detector will get me back on the spot. The PVC won't hurt any equipment it happens to go through. > > Almost everything I work with has a GPS. I did the first vehicle > units for www.ipsolutionsinc.com and all the software for spryer in > http://www.ppi-far.org/ppiweb/bcrops.nsf/$webindex/6041B8CEFFC83068852568F10056A8F7/$file/97-4p15.pdf!open > > Interesting, but availablily depends on the roots being able to find > nutrients and hence on the rainfall & intensity. It probably would not > work too well for things like moss and poor land grasses. The grab every > nutrient molecule going and store them. This was the problem in Finland > after the Chernobyl nuclear disaster. The grasses and moss which fed the > reindeer heards soaked up most of the radioactivity. It works for anything we have tried it on. It measures the nitrogen in the leaves of the wheat by looking at the ratio of narrow band of red and near infrared light in late winter just before it starts the process of going from vegetative state to a fruiting or grain producing stage. In this case we are adding fertilizer to the soil in the late winter because in the vegetative state wheat uses nitrogen to grow large lush leaves and in the grain producing stage it uses much more of it to make grain and much less to make leaves. Also nitrogen is some what perishable and can leach down below the root zone if there is too much rain or turn into ammonia and escape in atmosphere if water stands on the ground. So it takes less nitrogen to produce a bushel of wheat if it put one in February than if it is put on in the previous September. By putting it down in February or March we can assure that the nitrogen in the root zone where the plant can get it when it can make the most use of it. The fertilizer could just as well be foliar fertilizer that is taken up trough the leaves. In the case of most farm crops that is not an economic option because until you get rain the plant can't benefit from the fertilizer unless the ground is wet enough to take up the fertilizer. We found several strategies that gave more return on the dollar spent on fertilizer, First was to make the nitrogen level in the wheat as near the same everywhere in the field as we could. The generally cut the fertilizer use in half and the dyed didn't change. The next was leave the areas high in nitrogen alone and double up on the low spots. That used the same amount of fertilizer and increased yields 7%. If we added in the historical yield data and added fertilizer to the point that each area had enough nitrogen to yield it full potential we got about 10% increase. I would be surprised it the system if half as could as it could be with smaller sample sizes and more experience. This only works with nutrients such as nitrogen, zinc and few others that can be applied to a growing plant and still benefit it. Other nutrients phosphorus being the most important one need to be applied before the plant spouts and immediately available to the roots. In the case of Chernobyl strontium 90 is metabolized much like phosphorus and cesium is handled like potassium. So after the rain washed the fall out off the worst problme weren't probably seen until the next year and they did make an effort in some areas to deep plow the fall out under below the root zone of the grasses and fertilize with P and K to prevent the grasses from taking up as many radioactive isotopes as they could. That only worked on land that could be plowed and that is not were reindeer generally graze. > > I agree they are power hogs and take a lot of resources for time > for seismic senors that VLF will do just as well as GPS. I have > seen jitter on VLF from WWV in a really bad magnetic storm but > not as often as I have lost lock with the GPS. > > I don't get this problem at all often. The computer looks for an > interference free minute every half hour and then adjusts the precision > crystal oscillator offset on the 59 mean pulses. The drift is initially > set at less than 5 ppm and can be maintained down parts in 10^8 The problem is not very common it takes a really big magnetic storm to cause it an they don't happen often. The 5 volt one Hz signal off a Rockwell Jupiter or many other GPS receivers makes an ideal heart beat for a clock for an microcomputer. If you need finer granularity a divider or phased locked loop on the 100 kHz output is a bit harder to build but is easier than a VLF radio. Both your way with WWV VLF and a GPS have their place. But with GPS receivers with one second clock pins selling for 25 to 50 bucks new in the box it is hard to see why any one would go to the effort to use VLF unless there were problems that precluded using a GPS. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 13:52:05 -0500 Hi Doug > Snip > UnSnip > > This is not earthquake recording, this is exploration seismic. The > frequencies you care about will be between 10 and 500 Hz and a perfectly > normal sound card will handle these signals. You may need some preamps like > you would with a dynamic phonograph cartridge, because the signals from > geophones are small. > > You will need zero time from your shock source (a sledge hammer should be > adequate). The best choice is a small, cheap crystal phonograph cartridge > taped near the head connected to the second channel. You don't care about > absolute time, just time relative to the impact, so forget GPS timing. > I am using standard seismic sensors and I will probably use a ..22 or .38 fired into the ground or a slide hammer lifted up by a blank cartridge. My sledge hammer swinging days have been over for 20 years due to multiple sclerosis. I think I need a better clock than the computer has for relative measuring and I plan to divide down the 100 KHZ clock on the GPS to 1000 HZ and put on each channel of the sound card for a time base and reference. Each sensor will modulate an oscillator at a different frequency and all will be mixed together and recorded on the sound card and the 1000 HZ signal will be used to lock on to decoded the others as well as a time base that is automatically generated in the decoding process for each sensor. There is just too much jitter in everthing I have tested in windows to trust it to keep time even on a the sound card that is supposed to run in real time. There also has to be some point to referenced everthing from in both time and frequency. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 12:21:30 -0700 > Snip I am using standard seismic sensors and I will probably use a .22 or .38 fired into the ground or a slide hammer lifted up by a blank cartridge. = My sledge hammer swinging days have been over for 20 years due to multiple sclerosis. > unsnip Shooting bullets into the ground is not the best energy source; most of = the energy goes into plastic deformation instead of elastic waves. There = was a source made with an 8-gague kiln gun some years ago that generated a lot = of sound and fury, but barely kept up with a sledgehammer except when fired into saturated material.=20 The best gun-like source is the buffalo gun aka "in hole shotgun". You = take a 3/4-inch pipe about 4 feet long and screw a coupling on the end big = enough to hold a shotgun shell. You auger a hole in the ground and stick the = end with the shell down a foot or more. Then you drop a pointed rod down = the pipe to detonate the shell. The shell goes off underground and much = more of the energy is coupled to the soil. It works about as well with blanks = as with loaded shells. Search for in-hole shotgun source on the web and you will find some papers. The most descriptive here http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=3Dnormal&id=3D= GPYSA70 00052000007000985000001&idtype=3Dcvips&gifs=3Dyes There is a commercial version called the Betsy Seisgun, if you search = there you can see pictures of it, but the pipe version works just as well.=20 Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Thu, 21 Jul 2005 17:39:27 -0500 Doug Crice wrote: >>Snip > > > I am using standard seismic sensors and I will probably use a .22 or .38 > fired into the ground or a slide hammer lifted up by a blank cartridge. My > sledge hammer swinging days have been over for 20 years due to multiple > sclerosis. > > >>unsnip > > > Shooting bullets into the ground is not the best energy source; most of the > energy goes into plastic deformation instead of elastic waves. There was a > source made with an 8-gague kiln gun some years ago that generated a lot of > sound and fury, but barely kept up with a sledgehammer except when fired > into saturated material. > > The best gun-like source is the buffalo gun aka "in hole shotgun". You take > a 3/4-inch pipe about 4 feet long and screw a coupling on the end big enough > to hold a shotgun shell. You auger a hole in the ground and stick the end > with the shell down a foot or more. Then you drop a pointed rod down the > pipe to detonate the shell. The shell goes off underground and much more of > the energy is coupled to the soil. It works about as well with blanks as > with loaded shells. Search for in-hole shotgun source on the web and you > will find some papers. The most descriptive here > http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=GPYSA70 > 00052000007000985000001&idtype=cvips&gifs=yes > > There is a commercial version called the Betsy Seisgun, if you search there > you can see pictures of it, but the pipe version works just as well. > > Doug Crice http://www.geostuff.com > Wireless Seismic http://www.wirelessSeismic.com > 12996 Somerset Drive phone 1-530-274-4445 > Grass Valley, CA 95945 USA fax 1-530-274-4446 > Doug, I know a gun fired in the ground is not a good source and that's why I included a drop hammer lifted by a bank and dropped back on the rod that is attached to a steel plate that sets on the ground. I may have to use a propane to lift the slide over the piston instead of a blank shot gun shell, This fall when it cools off I will see what kind of hammer I need. Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 16:01:54 -0700 For as long as I have been in seismic, people have been trying to build = a good energy source for engineering seismic studies. Let me define such = a device for you experimenters out there. 1) A person ought to be able to carry it around 2) It needs reasonably high frequency output (ping instead of thunk) 3) Build it for $1000 or even $2000 in lots of 10 units, using new commercially available and machined parts. 4) It should be safe, even when used by students 5) There should be no significant regulatory issues (a problem with dynamite, the perfect source) 6) Operating supplies available in third world countries. 7) And last but not least, it needs to work better than a sledgehammer = used with a seismograph that can stack multiple impacts. The in-hole shotgun comes close, but it is possible to shoot yourself in = the foot, blow your hand off, and in one case, blow your brains out. The associated liability prevents any real company from producing the = device. Even if you made it impossible to accidentally hurt yourself, under our = tort system, you would still be liable for intentional injuries. Geostuff will be happy to sell the device using our worldwide network of contacts, assuming it works and is reliable. Mechanical things tend to = self destruct. =20 Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 I know a gun fired in the ground is not a good source and that's=20 why I included a drop hammer lifted by a bank and dropped back=20 on the rod that is attached to a steel plate that sets on the=20 ground. I may have to use a propane to lift the slide over the=20 piston instead of a blank shot gun shell, __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 19:22:06 EDT In a message dated 22/07/2005, dcrice@............ writes: 7) And last but not least, it needs to work better than a sledgehammer used with a seismograph that can stack multiple impacts. Hi Doug, This may be a bit ''off the wall'', but there is another way of looking at the problem. Can we design a better type of sledge hammer + plate / falling weight? Regards, Chris Chapman

In a message dated 22/07/2005, dcrice@............ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>7) And=20 last but not least, it needs to work better than a sledgehammer used
wi= th a=20 seismograph that can stack multiple impacts.

Hi Doug,

This may be a bit ''off the wall'', but there i= s=20 another way of looking at the problem.

Can we design a better type of sledge hammer +=20 plate / falling weight?

Regards,

Chris Chapman

Subject: RE: Modified sound card and datalogging and geophones From: "Doug Crice" dcrice@............ Date: Thu, 21 Jul 2005 16:47:11 -0700 A sledgehammer is operated by swinging it through about a 250 degree = arc, presumably by a muscular associate. If you were to replace it with a = weight drop, you would need to drop it many meters to approximate this amount = of energy. Thus, your weight needs to be accelerated somehow. There are = units that attach to vehicles with large rubber bands. They are cocked by electric or hydraulic devices. See photos on http://www.giscogeo.com/pages/giscosei.html=20 =20 We would like to make a significant improvement in energy output. You = could make a better hammer and plate, but probably not twice as good. =20 I have considered flywheel operated devices. You could spin up a = flywheel with a battery operated drill and then couple the energy into the ground somehow, though there are strange forces going in strange directions = when you suddenly stop a spinning flywheel. =20 Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of ChrisAtUpw@....... Sent: Thursday, July 21, 2005 4:22 PM To: psn-l@.............. Subject: Re: Modified sound card and datalogging and geophones =20 In a message dated 22/07/2005, dcrice@............ writes: 7) And last but not least, it needs to work better than a sledgehammer = used with a seismograph that can stack multiple impacts. Hi Doug, =20 This may be a bit ''off the wall'', but there is another way of = looking at the problem.=20 =20 Can we design a better type of sledge hammer + plate / falling = weight?=20 =20 Regards, =20 Chris Chapman

A sledgehammer = is operated by swinging it through about a 250 degree arc, presumably by a muscular associate. If you were to replace it with a weight drop, = you would need to drop it many meters to approximate this amount of energy. = Thus, your weight needs to be accelerated somehow. There are units that = attach to vehicles with large rubber bands. They are cocked by electric = or hydraulic devices. See photos on http://www.giscogeo.= com/pages/giscosei.html

We would like to make a significant = improvement in energy output. You could make a better hammer and plate, but = probably not twice = as good.

I have considered flywheel = operated devices. You could spin up a flywheel with a battery operated drill and = then couple the energy into the ground somehow, though there are strange = forces going in strange directions when you suddenly stop a spinning = flywheel.

Doug Crice = ; http://www.geostuff.com

Wireless Seismic = http://www.wirelessSeismic.com

12996 Somerset Drive &n= bsp; phone 1-530-274-4445

Grass Valley, CA = 95945 USA fax 1-530-274-4446

-----Original = Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@.......
Sent: Thursday, July 21, = 2005 4:22 PM
To: = psn-l@..............
Subject: Re: Modified = sound card and datalogging and geophones

In a message dated 22/07/2005, dcrice@............ writes:

7) And last but not least, it needs to work better than a sledgehammer used
with a seismograph that can stack multiple impacts.

Hi = Doug,

&nbs= p; This may be a bit ''off the wall'', but there is another way of looking at = the problem.

&nbs= p; Can we design a better type of sledge hammer + plate / falling weight? =

&nbs= p; Regards,

&nbs= p; Chris Chapman

Subject: Re: Modified sound card and datalogging and geophones From: BOB BARNS royb1@........... Date: Thu, 21 Jul 2005 20:57:23 -0400 Doug, For a "ground-pinger": make a fitting to attach a bicycle pump to the screw cap on a large plastic (one liter?) soda-pop bottle. Bury the bottle down to the neck (or deeper) and pump until the bottle fails. (I don't know how much pressure these things will stand.) It might be better to weaken (say by scoring) the bottom so the push is vertical rather than horizontal (as when the side fails). Alternatively, the sides could be reinforced by wrapping with duct tape. This scheme meets your criteria except the "multiple impact" and possibly the "ping instead of thump" but it's hard to beat for cheap. A glass bottle might be more ping-like but would leave a hazardous residue. Bottles made of a brittle plastic (e.g., polystyrene or methyl-methacralate) might be better that the usual. It would be easy to try (but not by me). I considered pumping water instead of air but air would give greater impact because the stored enrgy is much greater. That's why pressure testing of high pressure gas tanks (e.g., oxygen) uses water rather than a gas. Another scheme:introduce a standard spark plug into a pop-bottle just below the neck. Run two wires (thru a rubber stopper in the neck or a screw cap) into the borrom of the bottle into an inch or so of water. Bury the bottle. Pass current (for a predetermined time)thru the water which fill the bottle with oxygen and hydrogen (the mixture will be stoichiometric). Fire a spark thru the plug. A stoichiometric mix of oxygen and hydrogen will detonate, not just burn. This should give a "ping". I suppose that a blanket should cover the ground above the bottle to catch the spark plug. Bob Barns Doug Crice wrote: > For as long as I have been in seismic, people have been trying to build a > good energy source for engineering seismic studies. Let me define such a > device for you experimenters out there. > > 1) A person ought to be able to carry it around > 2) It needs reasonably high frequency output (ping instead of thunk) > 3) Build it for $1000 or even $2000 in lots of 10 units, using new > commercially available and machined parts. > 4) It should be safe, even when used by students > 5) There should be no significant regulatory issues (a problem with > dynamite, the perfect source) > 6) Operating supplies available in third world countries. > 7) And last but not least, it needs to work better than a sledgehammer used > with a seismograph that can stack multiple impacts. > > The in-hole shotgun comes close, but it is possible to shoot yourself in the > foot, blow your hand off, and in one case, blow your brains out. The > associated liability prevents any real company from producing the device. > Even if you made it impossible to accidentally hurt yourself, under our tort > system, you would still be liable for intentional injuries. > > Geostuff will be happy to sell the device using our worldwide network of > contacts, assuming it works and is reliable. Mechanical things tend to self > destruct. > > Doug Crice http://www.geostuff.com > Wireless Seismic http://www.wirelessSeismic.com > 12996 Somerset Drive phone 1-530-274-4445 > Grass Valley, CA 95945 USA fax 1-530-274-4446 > > > > I know a gun fired in the ground is not a good source and that's > why I included a drop hammer lifted by a bank and dropped back > on the rod that is attached to a steel plate that sets on the > ground. I may have to use a propane to lift the slide over the > piston instead of a blank shot gun shell, > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________ NOD32 1.1175 (20050721) Information __________ > > This message was checked by NOD32 antivirus system. > http://www.eset.com > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 21:11:32 EDT In a message dated 21/07/2005, gcouger@.......... writes: The 5 volt one Hz signal off a Rockwell Jupiter or many other GPS receivers makes an ideal heart beat for a clock for an microcomputer. If you need finer granularity a divider or phased locked loop on the 100 kHz output is a bit harder to build but is easier than a VLF radio. Both your way with WWV VLF and a GPS have their place. But with GPS receivers with one second clock pins selling for 25 to 50 bucks new in the box it is hard to see why any one would go to the effort to use VLF unless there were problems that precluded using a GPS. Hi Gordon, You need the timing pulses and the data stream to set the system clock. Larry sells a 2nd hand GPS, aerial and interface board for $140. You need all three. Please DO tell me where I can get this for $50, new, or even second hand? Regards, Chris Chapman

In a message dated 21/07/2005, gcouger@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The 5=20 volt one Hz signal off a Rockwell Jupiter or many other GPS receivers make= s an=20 ideal heart beat for a clock for an microcomputer. If you need finer=20 granularity a divider or phased locked loop on the 100 kHz output is a bit= =20 harder to build but
is easier than a VLF radio.

Both your way w= ith=20 WWV VLF and a GPS have their place. But with GPS receivers with one second= =20 clock pins selling for 25 to 50 bucks new in the box it is hard to see why= any=20 one would go to the effort to use VLF unless there were problems that=20 precluded using a GPS.

Hi Gordon,

You need the timing pulses and the data stream=20= to=20 set the system clock.

Larry sells a 2nd hand GPS, aerial a= nd=20 interface board for $140. You need all three.

Please DO tell me where I can get t= his=20 for $50, new, or even second hand?

Regards,

Chris Chapman

Subject: Re[2]: Modified sound card and datalogging and geophones From: Angel sismos@.............. Date: Thu, 21 Jul 2005 21:42:24 -0500 Bob, I like your style! Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Thu, 21 Jul 2005 23:01:25 EDT In a message dated 22/07/2005, royb1@........... writes: Doug, For a "ground-pinger": make a fitting to attach a bicycle pump to the screw cap on a large plastic (one liter?) soda-pop bottle. Bury the bottle down to the neck (or deeper) and pump until the bottle fails. (I don't know how much pressure these things will stand.) Hi Bob, You could fit a car tyre type valve into the cap and use a foot pump. I suspect that the bursting point will be quite temperature sensitive. It might be OK to pump it up to 100 psi or more and then jab the bottle with a knife on a long handle? This scheme meets your criteria except the "multiple impact" and possibly the "ping instead of thump" but it's hard to beat for cheap. A glass bottle might be more ping-like but would leave a hazardous residue. That would need an awful lot of pressure and flying glass is very dangeous. Another scheme:introduce a standard spark plug into a pop-bottle just below the neck. Run two wires (thru a rubber stopper in the neck or a screw cap) into the bottom of the bottle into an inch or so of water..... Umm? How about put 1/2" of water in the bottom, a couple of wires in through the cap, add a teaspoonful of calcium carbide, shake and wait a few minutes. Stand well clear and put a spark between the wires to fire the gas mixture? This sort of device is used in agricultural bird scarers and they produce a bang which can be heard for a mile or so. It might well be possible to adapt one for seismology? Alternatively, equip your self with some balloons, fill them with acetylene + oxygen and apply a glowing fuse or cigarette? I suggest setting the gas torch burning with the correct flame shape, wipe out the flame and then fill the balloon? A local school kid did this with one of the 3 ft weather balloons in is father's garage many years ago. He removed all the nearby windows for about 100 yards..... Regards, Chris Chapman

In a message dated 22/07/2005, royb1@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Doug,
For a "ground-pinger": make a fitting to at= tach a=20 bicycle pump to the
screw cap on a large plastic (one liter?) soda-pop= =20 bottle. Bury the
bottle down to the neck (or deeper) and pump un= til=20 the bottle fails. (I
don't know how much pressure these things w= ill=20 stand.)

Hi Bob,

You could fit a car tyre type valve into t= he=20 cap and use a foot pump. I suspect that the bursting point will be quite=20 temperature sensitive. It might be OK to pump it up to 100 psi or more and t= hen=20 jab the bottle with a knife on a long handle?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2> This scheme meets your criteria except the "multiple= =20 impact" and
possibly the "ping instead of thump" but it's hard to beat= for=20 cheap.
A glass bottle might be more ping-like but would le= ave=20 a hazardous
residue.

That would need an awful lot of pressure and fl= ying=20 glass is very dangeous.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2> Another scheme:introduce a standard spark plug into=20= a=20 pop-bottle just
below the neck. Run two wires (thru a rubber sto= pper=20 in the neck or a
screw cap) into the bottom of the bottle into an inch= or=20 so of water.....

Umm? How about put 1/2" of water in the bottom,= a=20 couple of wires in through the cap, add a teaspoonful of calcium carbide, sh= ake=20 and wait a few minutes. Stand well clear and put a spark between the wi= res=20 to fire the gas mixture?

This sort of device is used in agricultural bir= d=20 scarers and they produce a bang which can be heard for a mile or so. It migh= t=20 well be possible to adapt one for seismology?

Alternatively, equip your self with some balloo= ns,=20 fill them with acetylene + oxygen and apply a glowing fuse or cigarette? I=20 suggest setting the gas torch burning with the correct flame shape, wip= e=20 out the flame and then fill the balloon? A local school kid did this=20 with one of the 3 ft weather balloons in is father's garage many years=20= ago.=20 He removed all the nearby windows for about 100 yards.....

Regards,

Chris Chapman

In a message dated 22/07/2005, royb1@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2> The carbide idea has some charm (I have a carbide ca= nnon)=20 but careful
control of the acetylene-air ratio would be necessary to=20 achieve a
detonation. Electrolysis of water automatically insure= s=20 stoichiometry.

Hi Bob,

Agreed, but have you worked out how long it wou= ld=20 take to get sufficient H2 and O2 by electrolysis and the number of amp hours= =20 required?

You would need inert electrodes in the water +=20= lime=20 soda?

    You know the volume of the bottle and hence= the=20 volume of oxygen. You now need to weigh out the right amount of CaC2, tip it= in=20 the bottle and wait till it stops fizzling. It would probably be good enough= ?=20

>    Alternatively, equip your self with some=20 balloons, fill them with
> acetylene + oxygen and apply a glowing fus= e or=20 cigarette? I
> suggest setting the gas torch burning with the correct= =20 flame shape, wipe
> out the flame and then fill the=20 balloon?

   Again, stoichiometry would require carefu= l=20 control of gas-air ratio.
Also, balloons are harder to bury than=20 bottles.

The way my mind works, I was thinking of=20 using sausage shaped balloons blown up inside a thin cardboard tube. If= you=20 light the acetylene flame and adjust the O2 to get a cylindrical=20 blue centre, you have the correct gas ratio. You then push the flame on= to=20 a cold flat surface to snuff it out and use the nozzle to fill the=20 balloon?

This should work OK. It gets around having to h= ave=20 a license to handle explosives.

Regards,

Chris Chapman

I am truly sorry.

Mariam Marshall

felipe luevanos luevanos <felicaribe5@...........> wrote:

I am truly sorry, do you know when this happened?

Felipe Luevanos.

>From: Larry Cochrane
>Reply-To: psn-l@..............
>To: psn-l@..............
>Subject: Bruce Bolt has died
>Date: Fri, 22 Jul 2005 02:50:29 -0700
>
>All,
>
>I just read on a newsgroup that Bruce Bolt has passed away. I had the
>opportunity to meet him at a local conference a few years ago.
>
>Regards,
>Larry Cochrane
>Redwood City, PSN
>
>__________________________________________________________
>
>Public Seismic Network Mailing List (PSN-L)
>
>To leave this list email PSN-L-REQUEST@.............. with the body of the
>message (first line only): unsubscribe
>See http://www.seismicnet.com/maillist.html for more information.

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the body of the message (first line only): unsubscribe
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http://mail.yahoo.com Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Sat, 23 Jul 2005 00:47:57 -0500 Bob, A propane air mixture will detonate if the mix is just right it is used as fuel in detonation engines. The fuel to air ration is lot narrower and the conditions more critical than hydrogen or actetyene. Gordon BOB BARNS wrote: > Wayne, > I suspect that the propellant in the hairspray is a hydrocarbon such > as propane. > A propane-air mixture does not detonate; rather it burns rapidly like > gunpowder. This would provide a longer seismic pulse than the > detonation of hydrogen-oxygen or acetylene-air mixtures. > Bob > > > Wayne Francis wrote: > >> Just as an aside, some of these contraptions sound a little like my >> son's potato cannon. Along with the spark, it used Aqua-net hairspray as >> the volatile substance (would auto starter spray work?). Pretty good >> bang to fire that potato. They used PVC, but build one out of 2 inch >> steel pipe, give it a squirt, set it off with a sparker (they were >> experimenting with piezo, ie. barbeque striker). Might work. >> Wayne Francis >> Ojai, CA >> > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Bruce Bolt has died From: Col Lynam lynam@................ Date: Sat, 23 Jul 2005 16:38:22 +1000 Dear Psn BB readers I'd appreciate any references to any obituary for Bruce Bolt. I'd like to compose a small one to place in the newsletter for Aust earthquake Engineers Soc. Thanks all.. col lynam volunteer observor, QUAKES group, ESSCC centre, Uni of Queensland, Australia Dave Nelson wrote: > At 02:50 AM 22/07/2005 -0700, you wrote: > >> All, >> I just read on a newsgroup that Bruce Bolt has passed away. I had the >> opportunity to meet him at a local conference a few years ago. >> Regards, >> Larry Cochrane >> Redwood City, PSN > > > ohhhh wow :( what a sad loss to family, friends and associates, > my condolences to all > > I met Bruce in the mid 1990's when he visited Otago university, > Dunedin, NZ > where I did my geology degree. Bruce did a couple of guest speaker talks > ... one was on the response of the golden gate bridge to quakes > > It was so good to meet the man that really brought seismology home to me > during the late ' 70's and ' 80's through his publications. > > thanks Bruce > > Dave Nelson > Sydney, Oz > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > Dear Psn BB readers
I'd appreciate any references to any obituary for Bruce Bolt.
I'd like to compose a small one to place in the newsletter for Aust earthquake Engineers Soc.

Thanks all..
col lynam
volunteer observor, QUAKES group, ESSCC centre, Uni of Queensland, Australia

Dave Nelson wrote:

At 02:50 AM 22/07/2005 -0700, you wrote:

All,
I just read on a newsgroup that Bruce Bolt has passed away. I had the opportunity to meet him at a local conference a few years ago.
Regards,
Larry Cochrane
Redwood City, PSN

ohhhh wow :( what a sad loss to family, friends and associates,
my condolences to all

I met Bruce in the mid 1990's when he visited Otago university, Dunedin, NZ
where I did my geology degree. Bruce did a couple of guest speaker talks
.... one was on the response of the golden gate bridge to quakes

It was so good to meet the man that really brought seismology home to me
during the late ' 70's and ' 80's through his publications.

thanks Bruce

Dave Nelson
Sydney, Oz

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Subject: Re: Bruce Bolt has died <<<<< Memorial at UCB- >>>>> From: Jim E ODonnell jimo17@........ Date: Sat, 23 Jul 2005 04:09:28 -0700 Hi Larry- Many of your associates will be able to read about Bruce at the UCB site blow. I attended his first class he taught at UCB- with 5 other graduate students in geophysics. http://seismo.berkeley.edu/memorial/bruce_bolt/ Bruce Bolt 1930-2005 July 21, 2005 The faculty, staff, and students of the Berkeley Seismological Laboratory and the Departments of Earth and Planetary Science and Civil and Environmental Engineering are saddened by the loss of Professor Bruce Bolt, who passed away today after a brief illness. Professor Bolt joined UC Berkeley in 1963 as a professor of seismology in the Department of Earth and Planetary Science and the Director of the Berkeley Seismological Laboratory (then known as the Seismographic Stations). Professor Bolt was director of the BSL for 26 years, leading the development of the Berkeley seismographic network into the age of broadband instrumentation and digital recording. Professor Bolt leaves a rich legacy of accomplishments in seismology, engineering, and public policy. More information about Professor Bolt and his legacy will be posted here in the next few day >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> On Fri, 22 Jul 2005 02:50:29 -0700 Larry Cochrane writes: > All, > > I just read on a newsgroup that Bruce Bolt has passed away. I had > the opportunity to > meet him at a local conference a few years ago. > > Regards, > Larry Cochrane > Redwood City, PSN > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > >

Hi Larry-

Many of your associates will be able to read about Bruce at the UCB = site=20 blow.

I attended his first class he taught at UCB- with 5 other graduate = students=20 in geophysics.

http://seismo.= berkeley.edu/memorial/bruce_bolt/

= Bruce=20 Bolt 1930-2005

July 21, 2005

The faculty, staff, and students of the Berkeley Seismological = Laboratory and=20 the Departments of Earth and Planetary Science and Civil and Environmental= =20 Engineering are saddened by the loss of Professor Bruce Bolt, who passed = away=20 today after a brief illness.

Professor Bolt joined UC Berkeley in 1963 as a professor of seismology = in the=20 Department of Earth and Planetary Science and the Director of the Berkeley= =20 Seismological Laboratory (then known as the Seismographic Stations). = Professor=20 Bolt was director of the BSL for 26 years, leading the development of the=20 Berkeley seismographic network = into=20 the age of broadband instrumentation and digital recording.

Professor Bolt leaves a rich legacy of accomplishments in seismology,=20 engineering, and public policy.

More=20 information about Professor Bolt and his legacy will be posted here in the = next=20 few day

>>>>>>>>>>&= gt;>>>>>>>>>>>>>>>>>>= >>>>>>>>>>>>>>>>>>>= ;>>>>>>>>>>>>>>

On Fri, 22 Jul 2005 02:50:29 -0700 Larry Cochrane <lcochrane@..............>=20 writes:
> All,
>
> I just read on a newsgroup that Bruce= Bolt=20 has passed away. I had
> the opportunity to
> meet him at a = local=20 conference a few years ago.
>
> Regards,
> Larry=20 Cochrane
> Redwood City, PSN
>
>=20 __________________________________________________________
>
>= =20 Public Seismic Network Mailing List (PSN-L)
>
> To leave this = list=20 email PSN-L-REQUEST@.............. with=20
> the body of the message (first line only): unsubscribe
> See= http://www.seismicnet.com/= maillist.html=20 for more information.
>
>

Subject: Re: Digest from 07/22/2005 00:01:12 From: "Randy" rpratt@............. Date: Sat, 23 Jul 2005 08:23:45 -0500 Hi All, I came into the middle of this so not sure who to direct this to. I gather there is a need for some small explosions. I was recently looking at this site http://www.nakka-rocketry.net/index.html and on it there are some recipies for building rocket motors with sugar and potasium nitrate in PVC tubing. Just eliminate the nozzle. Randy ----- Original Message ----- From: To: Sent: Saturday, July 23, 2005 2:00 AM Subject: Digest from 07/22/2005 00:01:12 > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 1 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Bruce Bolt has died > From: Larry Cochrane > Date: Fri, 22 Jul 2005 02:50:29 -0700 > > All, > > I just read on a newsgroup that Bruce Bolt has passed away. I had the opportunity to > meet him at a local conference a few years ago. > > Regards, > Larry Cochrane > Redwood City, PSN > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 2 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Bruce Bolt has died > From: Dave Nelson > Date: Fri, 22 Jul 2005 20:25:53 +1000 > > At 02:50 AM 22/07/2005 -0700, you wrote: > >All, > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > >opportunity to meet him at a local conference a few years ago. > >Regards, > >Larry Cochrane > >Redwood City, PSN > > ohhhh wow :( what a sad loss to family, friends and associates, > my condolences to all > > I met Bruce in the mid 1990's when he visited Otago university, Dunedin, NZ > where I did my geology degree. Bruce did a couple of guest speaker talks > ... one was on the response of the golden gate bridge to quakes > > It was so good to meet the man that really brought seismology home to me > during the late ' 70's and ' 80's through his publications. > > thanks Bruce > > Dave Nelson > Sydney, Oz > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 3 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: RE: Modified sound card and datalogging and geophones > From: "James Hannon" > Date: Fri, 22 Jul 105 07:28:13 CDT > > To do any kind of survey at all you need many impacts so it is hard to imagine a gadget that beats a brute swinging a sledge for portability and multiple strikes. > > A couple of years ago I was sitting in the St Louis airport and noticed a slow vibration of my seat that almost felt like an earthquake. Looking out the window I saw that they were breaking up a runway to replace it. There was a machine that lifted a huge weight and dropped it on the concrete. It would slowly move along dropping the weight every six inches or so. I was a couple of hundred feed away and could still feel it. The machine was breaking up reinforced concrete about 2 feet thick. > That would have made one heck of a survey! :) > > Jim Hannon > > > ---------- Original Message ---------------------------------- > From: "Doug Crice" > Reply-To: psn-l@.............. > Date: Thu, 21 Jul 2005 16:47:11 -0700 > > >A sledgehammer is operated by swinging it through about a 250 degree arc, > >presumably by a muscular associate. If you were to replace it with a weight > >drop, you would need to drop it many meters to approximate this amount of > >energy. Thus, your weight needs to be accelerated somehow. There are units > >that attach to vehicles with large rubber bands. They are cocked by > >electric or hydraulic devices. See photos on > >http://www.giscogeo.com/pages/giscosei.html > > > > > > > >We would like to make a significant improvement in energy output. You could > >make a better hammer and plate, but probably not twice as good. > > > > > > > > I have considered flywheel operated devices. You could spin up a flywheel > >with a battery operated drill and then couple the energy into the ground > >somehow, though there are strange forces going in strange directions when > >you suddenly stop a spinning flywheel. > > > > > > > >Doug Crice http://www.geostuff.com > > > >Wireless Seismic http://www.wirelessSeismic.com > > > >12996 Somerset Drive phone 1-530-274-4445 > > > >Grass Valley, CA 95945 USA fax 1-530-274-4446 > > > > -- > Jim Hannon > http://www.fmtcs.com/web/jmhannon/ > 42,11.90N,91,39.26W > WB0TXL > -- > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 4 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Modified sound card and datalogging and geophones > From: BOB BARNS > Date: Fri, 22 Jul 2005 10:42:24 -0400 > > > > ChrisAtUpw@....... wrote: > > In a message dated 22/07/2005, royb1@........... writes: > > > > Doug, > > For a "ground-pinger": make a fitting to attach a bicycle pump to > > the > > screw cap on a large plastic (one liter?) soda-pop bottle. Bury the > > bottle down to the neck (or deeper) and pump until the bottle > > fails. (I > > don't know how much pressure these things will stand.) > > > > Hi Bob, > > > > You could fit a car tyre type valve into the cap and use a foot > > pump. I suspect that the bursting point will be quite temperature > > sensitive. It might be OK to pump it up to 100 psi or more and then jab > > the bottle with a knife on a long handle? > > I agree that the bursting point would be temperature sensitive but I > can't guess if that would be disabling. The ground temperature at one > location should be relatively constant for successive shots although > different location would see different temperatures. > A jab with a knife would probably result in a slower release of > energy (than the bursting of a bottle) and hence a smaller peak pulse. > > > > > This scheme meets your criteria except the "multiple impact" and > > possibly the "ping instead of thump" but it's hard to beat for cheap. > > A glass bottle might be more ping-like but would leave a hazardous > > residue. > > > > That would need an awful lot of pressure and flying glass is very > > dangeous. > > I agree. > > > > > > Another scheme:introduce a standard spark plug into a pop-bottle > > just > > below the neck. Run two wires (thru a rubber stopper in the neck or a > > screw cap) into the bottom of the bottle into an inch or so of > > water..... > > > > Umm? How about put 1/2" of water in the bottom, a couple of wires in > > through the cap, add a teaspoonful of calcium carbide, shake and wait a > > few minutes. Stand well clear and put a spark between the wires to fire > > the gas mixture? > > > > This sort of device is used in agricultural bird scarers and they > > produce a bang which can be heard for a mile or so. It might well be > > possible to adapt one for seismology? > > The carbide idea has some charm (I have a carbide cannon) but careful > control of the acetylene-air ratio would be necessary to achieve a > detonation. Electrolysis of water automatically insures stoichiometry. > > > > > Alternatively, equip your self with some balloons, fill them with > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > suggest setting the gas torch burning with the correct flame shape, wipe > > out the flame and then fill the balloon? A local school kid did this > > with one of the 3 ft weather balloons in is father's garage many years > > ago. He removed all the nearby windows for about 100 yards..... > > Again, stoichiometry would require careful control of gas-air ratio. > Also, balloons are harder to bury than bottles. > I can see that a 3 ft balloon is a good choice for window removal. > Bob > > > > > Regards, > > > > Chris Chapman > > > > > > __________ NOD32 1.1175 (20050721) Information __________ > > > > This message was checked by NOD32 antivirus system. > > http://www.eset.com > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 5 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: RE: Bruce Bolt has died > From: "Kareem at HeyJooJoo" > Date: Fri, 22 Jul 2005 08:22:10 -0700 > > I unfortunately never had the chance to meet him but would have liked to. I > believe all of our libraries owe quite a bit of gratitude to him for his > contribution of writings and research. > > I recalled when the Newcastle quake hit Australia some time following our > Loma Prieta Quake, he was interviewed about how rare it was to see a M5.6 > quake in that part of Australia. He referenced how his parents or > grandparents only talked of one strong quake in Australia. I guess that's > where he grew up as a child? > > > Kareem > > -----Original Message----- > From: Dave Nelson [mailto:davenn@................ > Sent: Friday, July 22, 2005 3:26 AM > To: psn-l@.............. > Subject: Re: Bruce Bolt has died > > At 02:50 AM 22/07/2005 -0700, you wrote: > >All, > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > >opportunity to meet him at a local conference a few years ago. > >Regards, > >Larry Cochrane > >Redwood City, PSN > > ohhhh wow :( what a sad loss to family, friends and associates, > my condolences to all > > I met Bruce in the mid 1990's when he visited Otago university, Dunedin, > NZ where I did my geology degree. Bruce did a couple of guest speaker talks > ... one was on the response of the golden gate bridge to quakes > > It was so good to meet the man that really brought seismology home to me > during the late ' 70's and ' 80's through his publications. > > thanks Bruce > > Dave Nelson > Sydney, Oz > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of the > message (first line only): unsubscribe See > http://www.seismicnet.com/maillist.html for more information. > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 6 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Modified sound card and datalogging and geophones > From: ChrisAtUpw@....... > Date: Fri, 22 Jul 2005 13:46:30 EDT > > > -------------------------------1122054390 > Content-Type: text/plain; charset="US-ASCII" > Content-Transfer-Encoding: 7bit > > In a message dated 22/07/2005, royb1@........... writes: > > The carbide idea has some charm (I have a carbide cannon) but careful > control of the acetylene-air ratio would be necessary to achieve a > detonation. Electrolysis of water automatically insures stoichiometry. > Hi Bob, > > Agreed, but have you worked out how long it would take to get sufficient > H2 and O2 by electrolysis and the number of amp hours required? > You would need inert electrodes in the water + lime soda? > > You know the volume of the bottle and hence the volume of oxygen. You > now need to weigh out the right amount of CaC2, tip it in the bottle and wait > till it stops fizzling. It would probably be good enough? > > > Alternatively, equip your self with some balloons, fill them with > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > suggest setting the gas torch burning with the correct flame shape, wipe > > out the flame and then fill the balloon? > > Again, stoichiometry would require careful control of gas-air ratio. > Also, balloons are harder to bury than bottles. > > > > The way my mind works, I was thinking of using sausage shaped balloons blown > up inside a thin cardboard tube. If you light the acetylene flame and adjust > the O2 to get a cylindrical blue centre, you have the correct gas ratio. You > then push the flame onto a cold flat surface to snuff it out and use the > nozzle to fill the balloon? > > This should work OK. It gets around having to have a license to handle > explosives. > > Regards, > > Chris Chapman > > -------------------------------1122054390 > Content-Type: text/html; charset="US-ASCII" > Content-Transfer-Encoding: quoted-printable > > > > > > Arial"=20 > bottomMargin=3D7 leftMargin=3D7 topMargin=3D7 rightMargin=3D7> e_document=20 > face=3DArial color=3D#000000 size=3D2> >

In a message dated 22/07/2005, royb1@........... writes:

> style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><= > FONT=20 > style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 > size=3D2> The carbide idea has some charm (I have a carbide ca= > nnon)=20 > but careful
control of the acetylene-air ratio would be necessary to=20 > achieve a
detonation. Electrolysis of water automatically insure= > s=20 > stoichiometry. >

Hi Bob,

Agreed, but have you worked out how long it wou= > ld=20 > take to get sufficient H2 and O2 by electrolysis and the number of amp hours= > =20 > required?

You would need inert electrodes in the water +=20= > lime=20 > soda?

000=20 > size=3D2>    You know the volume of the bottle and hence= > the=20 > volume of oxygen. You now need to weigh out the right amount of CaC2, tip it= > in=20 > the bottle and wait till it stops fizzling. It would probably be good enough= > ?=20 >

>    Alternatively, equip your self with some=20 > balloons, fill them with
> acetylene + oxygen and apply a glowing fus= > e or=20 > cigarette? I
> suggest setting the gas torch burning with the correct= > =20 > flame shape, wipe
> out the flame and then fill the=20 > balloon?

   Again, stoichiometry would require carefu= > l=20 > control of gas-air ratio.
Also, balloons are harder to bury than=20 > bottles.

The way my mind works, I was thinking of=20 > using sausage shaped balloons blown up inside a thin cardboard tube. If= > you=20 > light the acetylene flame and adjust the O2 to get a cylindrical=20 > blue centre, you have the correct gas ratio. You then push the flame on= > to=20 > a cold flat surface to snuff it out and use the nozzle to fill the=20 > balloon?

This should work OK. It gets around having to h= > ave=20 > a license to handle explosives.

Regards,

Chris Chapman

> > -------------------------------1122054390-- > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 7 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Modified sound card and datalogging and geophones > From: "James Hannon" > Date: Fri, 22 Jul 105 12:56:29 CDT > > Just about any mixture of acetylene and air or oxygen will detonate. Under the right conditions pure acetylene will detonate. Last year I filled a small (6 inch dia filled) ballon with acetylene and oxygen with the correct mixture and set it off. You really do not want to be anywhere near when it goes off! My ears were ringing for hours and I could feel the pressure wave push my pant legs back. Problem is that I am not sure how you would couple this explosion into the ground. Put on the surface the force would just reflect off the ground. So it would have to be buried. There is also a safety issue -- any tiny static charge on the ballon would set off the explosion and easily hurt someone. > Jim Hannon > > ---------- Original Message ---------------------------------- > From: ChrisAtUpw@....... > Reply-To: psn-l@.............. > Date: Fri, 22 Jul 2005 13:46:30 EDT > > >In a message dated 22/07/2005, royb1@........... writes: > > > >The carbide idea has some charm (I have a carbide cannon) but careful > >control of the acetylene-air ratio would be necessary to achieve a > >detonation. Electrolysis of water automatically insures stoichiometry. > >Hi Bob, > > > > Agreed, but have you worked out how long it would take to get sufficient > >H2 and O2 by electrolysis and the number of amp hours required? > > You would need inert electrodes in the water + lime soda? > > > > You know the volume of the bottle and hence the volume of oxygen. You > >now need to weigh out the right amount of CaC2, tip it in the bottle and wait > >till it stops fizzling. It would probably be good enough? > > > >> Alternatively, equip your self with some balloons, fill them with > >> acetylene + oxygen and apply a glowing fuse or cigarette? I > >> suggest setting the gas torch burning with the correct flame shape, wipe > >> out the flame and then fill the balloon? > > > >Again, stoichiometry would require careful control of gas-air ratio. > >Also, balloons are harder to bury than bottles. > > > > > > > >The way my mind works, I was thinking of using sausage shaped balloons blown > >up inside a thin cardboard tube. If you light the acetylene flame and adjust > >the O2 to get a cylindrical blue centre, you have the correct gas ratio. You > >then push the flame onto a cold flat surface to snuff it out and use the > >nozzle to fill the balloon? > > > > This should work OK. It gets around having to have a license to handle > >explosives. > > > > Regards, > > > > Chris Chapman > > > > > -- > Jim Hannon > http://www.fmtcs.com/web/jmhannon/ > 42,11.90N,91,39.26W > WB0TXL > -- > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 8 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: RE: Modified sound card and datalogging and geophones > From: "Wayne Francis" > Date: Fri, 22 Jul 2005 11:22:23 -0700 > > Just as an aside, some of these contraptions sound a little like my > son's potato cannon. Along with the spark, it used Aqua-net hairspray as > the volatile substance (would auto starter spray work?). Pretty good > bang to fire that potato. They used PVC, but build one out of 2 inch > steel pipe, give it a squirt, set it off with a sparker (they were > experimenting with piezo, ie. barbeque striker). Might work. > Wayne Francis > Ojai, CA > > -----Original Message----- > From: psn-l-request@.............. [mailto:psn-l-request@............... > On Behalf Of BOB BARNS > Sent: Friday, July 22, 2005 7:42 AM > To: psn-l@.............. > Subject: Re: Modified sound card and datalogging and geophones > > > > ChrisAtUpw@....... wrote: > > In a message dated 22/07/2005, royb1@........... writes: > > > > Doug, > > For a "ground-pinger": make a fitting to attach a bicycle pump > to > > the > > screw cap on a large plastic (one liter?) soda-pop bottle. Bury > the > > bottle down to the neck (or deeper) and pump until the bottle > > fails. (I > > don't know how much pressure these things will stand.) > > > > Hi Bob, > > > > You could fit a car tyre type valve into the cap and use a foot > > pump. I suspect that the bursting point will be quite temperature > > sensitive. It might be OK to pump it up to 100 psi or more and then > jab > > the bottle with a knife on a long handle? > > I agree that the bursting point would be temperature sensitive but I > > can't guess if that would be disabling. The ground temperature at one > location should be relatively constant for successive shots although > different location would see different temperatures. > A jab with a knife would probably result in a slower release of > energy (than the bursting of a bottle) and hence a smaller peak pulse. > > > > > This scheme meets your criteria except the "multiple impact" > and > > possibly the "ping instead of thump" but it's hard to beat for > cheap. > > A glass bottle might be more ping-like but would leave a > hazardous > > residue. > > > > That would need an awful lot of pressure and flying glass is very > > dangeous. > > I agree. > > > > > > Another scheme:introduce a standard spark plug into a > pop-bottle > > just > > below the neck. Run two wires (thru a rubber stopper in the neck > or a > > screw cap) into the bottom of the bottle into an inch or so of > > water..... > > > > Umm? How about put 1/2" of water in the bottom, a couple of wires > in > > through the cap, add a teaspoonful of calcium carbide, shake and wait > a > > few minutes. Stand well clear and put a spark between the wires to > fire > > the gas mixture? > > > > This sort of device is used in agricultural bird scarers and they > > produce a bang which can be heard for a mile or so. It might well be > > possible to adapt one for seismology? > > The carbide idea has some charm (I have a carbide cannon) but careful > > control of the acetylene-air ratio would be necessary to achieve a > detonation. Electrolysis of water automatically insures stoichiometry. > > > > > Alternatively, equip your self with some balloons, fill them with > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > suggest setting the gas torch burning with the correct flame shape, > wipe > > out the flame and then fill the balloon? A local school kid did this > > with one of the 3 ft weather balloons in is father's garage many years > > > ago. He removed all the nearby windows for about 100 yards..... > > Again, stoichiometry would require careful control of gas-air ratio. > Also, balloons are harder to bury than bottles. > I can see that a 3 ft balloon is a good choice for window removal. > Bob > > > > > Regards, > > > > Chris Chapman > > > > > > __________ NOD32 1.1175 (20050721) Information __________ > > > > This message was checked by NOD32 antivirus system. > > http://www.eset.com > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 9 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: RE: Bruce Bolt has died > From: "felipe luevanos luevanos" > Date: Fri, 22 Jul 2005 18:27:16 +0000 > > I am truly sorry, do you know when this happened? > > Felipe Luevanos. > > >From: Larry Cochrane > >Reply-To: psn-l@.............. > >To: psn-l@.............. > >Subject: Bruce Bolt has died > >Date: Fri, 22 Jul 2005 02:50:29 -0700 > > > >All, > > > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > >opportunity to meet him at a local conference a few years ago. > > > >Regards, > >Larry Cochrane > >Redwood City, PSN > > > >__________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email PSN-L-REQUEST@.............. with the body of the > >message (first line only): unsubscribe > >See http://www.seismicnet.com/maillist.html for more information. > > _________________________________________________________________ > Express yourself instantly with MSN Messenger! Download today it's FREE! > http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 10 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Modified sound card and datalogging and geophones > From: Karl Cunningham > Date: Fri, 22 Jul 2005 17:31:44 -0700 > > Hi All -- > > My son used to set off 2-liter soda bottles by putting some dry ice in them > and then screwing on the cap. It takes about 5 minutes for it to build up > enough pressure to burst the bottle, but less if the bottle is in contact > with the ground. I would try doing this by augering a hole in the ground > (or use a post-hole shovel) just large enough to fit the soda bottle, then > covering the hole with something solid (concrete blocks) just after the cap > has been screwed onto the bottle. This may be the least expensive method > and should produce a relatively high-frequency content. The report from > the bottle exploding in air can be heard for over a mile and I can attest > that it annoys neighbors and attracts police attention. Examining a bottle > after the explosion, it appears the explosion happens quite quickly. The > bottle is opened starting from the bottom like petals of a flower, with the > cap at the center. > > I have tried blowing out an acetylene torch then feeding the gas into an > empty container, then igniting it with a spark plug. Have gotten mixed > results. Not sure why. > > I have done the "potato cannon" using ether, available at auto-parts stores > in aerosol cans as engine-starting fluid. After setting them off dozens of > times though, the results are far from uniform. Probably due to > poorly-controlled fuel-to-air ratio. > > Regards, > Karl Cunningham > > > --On Friday, July 22, 2005 1:46 PM -0400 ChrisAtUpw@....... wrote: > > > In a message dated 22/07/2005, royb1@........... writes: > > > > The carbide idea has some charm (I have a carbide cannon) but careful > > control of the acetylene-air ratio would be necessary to achieve a > > detonation. Electrolysis of water automatically insures stoichiometry. > > Hi Bob, > > > > Agreed, but have you worked out how long it would take to get > > sufficient H2 and O2 by electrolysis and the number of amp hours > > required? You would need inert electrodes in the water + lime soda? > > > > You know the volume of the bottle and hence the volume of oxygen. > > You now need to weigh out the right amount of CaC2, tip it in the > > bottle and wait till it stops fizzling. It would probably be good > > enough? > > > >> Alternatively, equip your self with some balloons, fill them with > >> acetylene + oxygen and apply a glowing fuse or cigarette? I > >> suggest setting the gas torch burning with the correct flame shape, > >> wipe out the flame and then fill the balloon? > > > > Again, stoichiometry would require careful control of gas-air ratio. > > Also, balloons are harder to bury than bottles. > > > > > > > > The way my mind works, I was thinking of using sausage shaped balloons > > blown up inside a thin cardboard tube. If you light the acetylene flame > > and adjust the O2 to get a cylindrical blue centre, you have the > > correct gas ratio. You then push the flame onto a cold flat surface to > > snuff it out and use the nozzle to fill the balloon? > > > > This should work OK. It gets around having to have a license to > > handle explosives. > > > > Regards, > > > > Chris Chapman > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 11 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Modified sound card and datalogging and geophones > From: BOB BARNS > Date: Fri, 22 Jul 2005 21:06:00 -0400 > > > > ChrisAtUpw@....... wrote: > > In a message dated 22/07/2005, royb1@........... writes: > > > > The carbide idea has some charm (I have a carbide cannon) but > > careful > > control of the acetylene-air ratio would be necessary to achieve a > > detonation. Electrolysis of water automatically insures stoichiometry. > > > > Hi Bob, > > > > Agreed, but have you worked out how long it would take to get > > sufficient H2 and O2 by electrolysis and the number of amp hours required? > > You would need inert electrodes in the water + lime soda? > > Salt water and carbon electrodes would work BUT, as often happens, > the devil is in the details. I calc. that to get 1 liter of > oxy-hydrogen mixture reqires 10 amps for 14 mins. I think this is > unworkable. > The CaC2 scheme should be much better. > > > > You know the volume of the bottle and hence the volume of oxygen. > > You now need to weigh out the right amount of CaC2, tip it in the bottle > > and wait till it stops fizzling. It would probably be good enough? > > > > > Alternatively, equip your self with some balloons, fill them with > > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > > suggest setting the gas torch burning with the correct flame shape, wipe > > > out the flame and then fill the balloon? > > > > Again, stoichiometry would require careful control of gas-air ratio. > > Also, balloons are harder to bury than bottles. > > > > The way my mind works, I was thinking of using sausage shaped > > balloons blown up inside a thin cardboard tube. If you light the > > acetylene flame and adjust the O2 to get a cylindrical blue centre, you > > have the correct gas ratio. You then push the flame onto a cold flat > > surface to snuff it out and use the nozzle to fill the balloon? > > I like this method except that it requires lugging around acetylene > and oxygen tanks. Perhaps the balloons could be filled at a central > site and then taken into the field. > Another thought pertinent to all these schemes: the top of the gas > container should be some distance below ground level and dirt packed > above the container. This provides directing the force of explosion > into the ground rather than letting it be expended into the air. This > is called "tamping". See > http://www.mektonzeta.com/archive/explosives.php > Bob > > > > > This should work OK. It gets around having to have a license to > > handle explosives. > > > > Regards, > > > > Chris Chapman > > > > > > __________ NOD32 1.1176 (20050722) Information __________ > > > > This message was checked by NOD32 antivirus system. > > http://www.eset.com > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 12 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Modified sound card and datalogging and geophones > From: BOB BARNS > Date: Fri, 22 Jul 2005 21:10:59 -0400 > > Wayne, > I suspect that the propellant in the hairspray is a hydrocarbon such > as propane. > A propane-air mixture does not detonate; rather it burns rapidly like > gunpowder. This would provide a longer seismic pulse than the > detonation of hydrogen-oxygen or acetylene-air mixtures. > Bob > > > Wayne Francis wrote: > > > Just as an aside, some of these contraptions sound a little like my > > son's potato cannon. Along with the spark, it used Aqua-net hairspray as > > the volatile substance (would auto starter spray work?). Pretty good > > bang to fire that potato. They used PVC, but build one out of 2 inch > > steel pipe, give it a squirt, set it off with a sparker (they were > > experimenting with piezo, ie. barbeque striker). Might work. > > Wayne Francis > > Ojai, CA > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 13 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: RE: Bruce Bolt has died > From: Mariam Kaba-Marshall > Date: Fri, 22 Jul 2005 18:18:49 -0700 (PDT) > > --0-297853181-1122081529=:48544 > Content-Type: text/plain; charset=iso-8859-1 > Content-Transfer-Encoding: 8bit > > I am truly sorry. > > Mariam Marshall > > felipe luevanos luevanos wrote: > I am truly sorry, do you know when this happened? > > Felipe Luevanos. > > >From: Larry Cochrane > >Reply-To: psn-l@.............. > >To: psn-l@.............. > >Subject: Bruce Bolt has died > >Date: Fri, 22 Jul 2005 02:50:29 -0700 > > > >All, > > > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > >opportunity to meet him at a local conference a few years ago. > > > >Regards, > >Larry Cochrane > >Redwood City, PSN > > > >__________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email PSN-L-REQUEST@.............. with the body of the > >message (first line only): unsubscribe > >See http://www.seismicnet.com/maillist.html for more information. > > _________________________________________________________________ > Express yourself instantly with MSN Messenger! Download today it's FREE! > http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > > > MariamKMarshall > > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > --0-297853181-1122081529=:48544 > Content-Type: text/html; charset=iso-8859-1 > Content-Transfer-Encoding: 8bit > >

I am truly sorry.

Mariam Marshall

felipe luevanos luevanos <felicaribe5@...........> wrote:

I am truly sorry, do you know when this happened?

Felipe Luevanos.

>From: Larry Cochrane
>Reply-To: psn-l@..............
>To: psn-l@..............
>Subject: Bruce Bolt has died
>Date: Fri, 22 Jul 2005 02:50:29 -0700
>
>All,
>
>I just read on a newsgroup that Bruce Bolt has passed away. I had the
>opportunity to meet him at a local conference a few years ago.
>
>Regards,
>Larry Cochrane
>Redwood City, PSN
>
>_________________________________________________________ _
>
>Public Seismic Network Mailing List (PSN-L)
>
>To leave this list email PSN-L-REQUEST@.............. with the body of the
>message (first line only): unsubscribe
>See http://www.seismicnet.com/maillist.html for more > information.

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MariamKMarshall

___ _______________________________________________
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http://mail.yahoo.com > --0-297853181-1122081529=:48544-- > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 14 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Modified sound card and datalogging and geophones > From: Gordon Couger > Date: Sat, 23 Jul 2005 00:47:57 -0500 > > Bob, > > A propane air mixture will detonate if the mix is just right it > is used as fuel in detonation engines. The fuel to air ration is > lot narrower and the conditions more critical than hydrogen or > actetyene. > > Gordon > > BOB BARNS wrote: > > Wayne, > > I suspect that the propellant in the hairspray is a hydrocarbon such > > as propane. > > A propane-air mixture does not detonate; rather it burns rapidly like > > gunpowder. This would provide a longer seismic pulse than the > > detonation of hydrogen-oxygen or acetylene-air mixtures. > > Bob > > > > > > Wayne Francis wrote: > > > >> Just as an aside, some of these contraptions sound a little like my > >> son's potato cannon. Along with the spark, it used Aqua-net hairspray as > >> the volatile substance (would auto starter spray work?). Pretty good > >> bang to fire that potato. They used PVC, but build one out of 2 inch > >> steel pipe, give it a squirt, set it off with a sparker (they were > >> experimenting with piezo, ie. barbeque striker). Might work. > >> Wayne Francis > >> Ojai, CA > >> > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with the body of > > the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 15 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Re: Bruce Bolt has died > From: Col Lynam > Date: Sat, 23 Jul 2005 16:38:22 +1000 > > This is a multi-part message in MIME format. > --------------090006060605090302030801 > Content-Type: text/plain; charset=us-ascii; format=flowed > Content-Transfer-Encoding: 7bit > > Dear Psn BB readers > I'd appreciate any references to any obituary for Bruce Bolt. > I'd like to compose a small one to place in the newsletter for Aust > earthquake Engineers Soc. > > Thanks all.. > col lynam > volunteer observor, QUAKES group, ESSCC centre, Uni of Queensland, Australia > > Dave Nelson wrote: > > > At 02:50 AM 22/07/2005 -0700, you wrote: > > > >> All, > >> I just read on a newsgroup that Bruce Bolt has passed away. I had the > >> opportunity to meet him at a local conference a few years ago. > >> Regards, > >> Larry Cochrane > >> Redwood City, PSN > > > > > > ohhhh wow :( what a sad loss to family, friends and associates, > > my condolences to all > > > > I met Bruce in the mid 1990's when he visited Otago university, > > Dunedin, NZ > > where I did my geology degree. Bruce did a couple of guest speaker talks > > ... one was on the response of the golden gate bridge to quakes > > > > It was so good to meet the man that really brought seismology home to me > > during the late ' 70's and ' 80's through his publications. > > > > thanks Bruce > > > > Dave Nelson > > Sydney, Oz > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with the body of > > the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > > --------------090006060605090302030801 > Content-Type: text/html; charset=us-ascii > Content-Transfer-Encoding: 7bit > > > > > > > > > Dear Psn BB readers
> I'd appreciate any references to any obituary for Bruce Bolt.
> I'd like to compose a small one to place in the newsletter for Aust > earthquake Engineers Soc.
>
> Thanks all..
> col lynam
> volunteer observor, QUAKES group, ESSCC centre, Uni of Queensland, > Australia
>
> Dave Nelson wrote:
>

cite="mid5.1.0.14.1.20050722201958.01de7ce0@....................">At > 02:50 AM 22/07/2005 -0700, you wrote: >
>
All, >
> I just read on a newsgroup that Bruce Bolt has passed away. I had the > opportunity to meet him at a local conference a few years ago. >
> Regards, >
> Larry Cochrane >
> Redwood City, PSN >
>
>
> ohhhh wow :( what a sad loss to family, friends and associates, >
> my condolences to all >
>
> I met Bruce in the mid 1990's when he visited Otago university, > Dunedin, NZ >
> where I did my geology degree. Bruce did a couple of guest speaker > talks >
> ... one was on the response of the golden gate bridge to quakes >
>
> It was so good to meet the man that really brought seismology home to > me >
> during the late ' 70's and ' 80's through his publications. >
>
> thanks Bruce >
>
> Dave Nelson >
> Sydney, Oz >
>
>
> __________________________________________________________ >
>
> Public Seismic Network Mailing List (PSN-L) >
>
> To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe >
> See http://www.seismicnet.com/mai llist.html for more information. >
>
>

> > > > --------------090006060605090302030801-- > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-DIGEST-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: BOB BARNS royb1@........... Date: Sat, 23 Jul 2005 10:01:34 -0400 Gordon, The little I have read ( http://www.aardvark.co.nz/pjet/pde.shtml ) suggests that something other than the correct fuel-air ratio is needed to cause detonation. Bob Gordon Couger wrote: > Bob, > > A propane air mixture will detonate if the mix is just right it is used > as fuel in detonation engines. The fuel to air ration is lot narrower > and the conditions more critical than hydrogen or actetyene. > > Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Seismic Energy Source From: "Doug Crice" dcrice@............ Date: Sat, 23 Jul 2005 07:11:24 -0700 Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 I have greatly enjoyed this discourse on a better exploration seismic source, and look forward to more ideas. To kind of remind folks of the specifications, I would like to repeat and expand them. 1) A person ought to be able to carry it around (and be air mobile by regular air freight). 2) It needs reasonably high frequency output (ping instead of thunk) 3) Build it for $1000-$2000 (cost, not sales price) in lots of 10 units, using commercially available and machined parts and normal labor rates. 4) It should be safe, even when used by students 5) There should be no significant regulatory issues (a problem with dynamite, the perfect source) 6) Operating supplies available in third world countries. 7) It needs to work better than a sledgehammer used with a seismograph = that can stack multiple impacts. 8) Because the source will probably be used in a repetitive fashion, it needs a reasonably fast cycle time (many seconds, not many minutes). 9) The seismic signature should approximate a zero phase wavelet, which = as a practical matter; means the energy prior to impact should be = comparatively modest. 10) Good ground coupling is needed. In the case of a sledgehammer, a = metal plate is placed on the ground as a target. In the in-hole shotgun, a = hole is augured just big enough to hold the device below the soft topsoil and preferably watered. The crossbow idea is equivalent to the "elastic wave generator", powered = by the large rubber band. Existing units weigh a couple of hundred pounds, = but it's got me thinking about a portable version. The variations on exploding bottles don't seem to meet the requirements = for reasonably safe operation. Sure, a careful user would be safe, but we = are talking about students and third-world laborers. An earlier variation was the "vacuum assisted weight drop". It had a 6 = ft (2 meter) long tube about 6 inches (15 cm) in diameter with a 100 pound = steel bullet inside. The bullet was pushed up with air pressure, then = evacuated. When the tube was full of vacuum, it was released and accelerated by its weight and by atmospheric air pressure. At the bottom was a 100 pound = anvil and plate combination pressed on the ground by the weight of the whole mechanism. With equal weights for the piston and anvil, it didn't bounce (think of that ball bearing toy). The VAWD worked reasonably well, but weighed 1000 pounds and cost over $10K 20 years ago. Using air pressure = as the accelerant provided a nice signature, since the force was external = to the system, though when you released the piston, it instantly lost 100 pounds of weight, providing the equivalent of a negative sledgehammer = blow. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: John or Jan Lahr JohnJan@........ Date: Sat, 23 Jul 2005 07:56:04 -0700 Given today's world, lets not make the PSN list one more place to learn about bomb making! This has been an interesting topic, but I think it's quite a tangent from amateur seismology for most of us.

Just my opinion, added with all due respect to all of the interesting suggestions that have been contributed.

Cheers,
John

##################################/ John C. Lahr
#################################/ Emeritus Seismologist
################################/ U.S. Geological Survey
===========================/ Geologic Hazards Team
##############################/ Golden, Colorado
#############################//##############################
############################//###############################
                             PO Box 548 /################################
             Corvallis, Oregon 97339 /##################################
             Phone: (541) 758-2699 /=============================
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             Fax: (928) 569-0113 /##################################
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                                 http://jclahr.com/science/
Subject: RE: Digest from 07/22/2005 00:01:12 From: "Jonathan Peakall" jpeakall@............ Date: Sat, 23 Jul 2005 08:36:43 -0700 Randy, Also change the formula of the fuel mix. Rockets use a formula designed to burn not explode. Also, it terms of shaped charges, a hubcap packed with explosive and covered with sandbags makes a great shaped charge. You should see what it does to refrigerators and old cars ;-0 Jonathan > -----Original Message----- > From: psn-l-request@.............. > [mailto:psn-l-request@................. Behalf Of Randy > Sent: Saturday, July 23, 2005 5:24 AM > To: psn-l@.............. > Subject: Re: Digest from 07/22/2005 00:01:12 > > > Hi All, > > I came into the middle of this so not sure who to direct this to. > I gather > there is a need for some small explosions. I was recently looking at this > site http://www.nakka-rocketry.net/index.html and on it there are some > recipies for building rocket motors with sugar and potasium nitrate in PVC > tubing. Just eliminate the nozzle. > > Randy > > ----- Original Message ----- > From: > To: > Sent: Saturday, July 23, 2005 2:00 AM > Subject: Digest from 07/22/2005 00:01:12 > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 1 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Bruce Bolt has died > > From: Larry Cochrane > > Date: Fri, 22 Jul 2005 02:50:29 -0700 > > > > All, > > > > I just read on a newsgroup that Bruce Bolt has passed away. I had the > opportunity to > > meet him at a local conference a few years ago. > > > > Regards, > > Larry Cochrane > > Redwood City, PSN > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 2 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Bruce Bolt has died > > From: Dave Nelson > > Date: Fri, 22 Jul 2005 20:25:53 +1000 > > > > At 02:50 AM 22/07/2005 -0700, you wrote: > > >All, > > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > > >opportunity to meet him at a local conference a few years ago. > > >Regards, > > >Larry Cochrane > > >Redwood City, PSN > > > > ohhhh wow :( what a sad loss to family, friends and associates, > > my condolences to all > > > > I met Bruce in the mid 1990's when he visited Otago > university, Dunedin, > NZ > > where I did my geology degree. Bruce did a couple of guest speaker talks > > ... one was on the response of the golden gate bridge to quakes > > > > It was so good to meet the man that really brought seismology home to me > > during the late ' 70's and ' 80's through his publications. > > > > thanks Bruce > > > > Dave Nelson > > Sydney, Oz > > > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 3 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: RE: Modified sound card and datalogging and geophones > > From: "James Hannon" > > Date: Fri, 22 Jul 105 07:28:13 CDT > > > > To do any kind of survey at all you need many impacts so it is hard to > imagine a gadget that beats a brute swinging a sledge for portability and > multiple strikes. > > > > A couple of years ago I was sitting in the St Louis airport and > noticed a > slow vibration of my seat that almost felt like an earthquake. Looking out > the window I saw that they were breaking up a runway to replace it. There > was a machine that lifted a huge weight and dropped it on the concrete. It > would slowly move along dropping the weight every six inches or > so. I was a > couple of hundred feed away and could still feel it. The machine was > breaking up reinforced concrete about 2 feet thick. > > That would have made one heck of a survey! :) > > > > Jim Hannon > > > > > > ---------- Original Message ---------------------------------- > > From: "Doug Crice" > > Reply-To: psn-l@.............. > > Date: Thu, 21 Jul 2005 16:47:11 -0700 > > > > >A sledgehammer is operated by swinging it through about a 250 > degree arc, > > >presumably by a muscular associate. If you were to replace it with a > weight > > >drop, you would need to drop it many meters to approximate > this amount of > > >energy. Thus, your weight needs to be accelerated somehow. There are > units > > >that attach to vehicles with large rubber bands. They are cocked by > > >electric or hydraulic devices. See photos on > > >http://www.giscogeo.com/pages/giscosei.html > > > > > > > > > > > >We would like to make a significant improvement in energy output. You > could > > >make a better hammer and plate, but probably not twice as good. > > > > > > > > > > > > I have considered flywheel operated devices. You could spin up a > flywheel > > >with a battery operated drill and then couple the energy into > the ground > > >somehow, though there are strange forces going in strange > directions when > > >you suddenly stop a spinning flywheel. > > > > > > > > > > > >Doug Crice http://www.geostuff.com > > > > > >Wireless Seismic http://www.wirelessSeismic.com > > > > > >12996 Somerset Drive phone 1-530-274-4445 > > > > > >Grass Valley, CA 95945 USA fax 1-530-274-4446 > > > > > > > -- > > Jim Hannon > > http://www.fmtcs.com/web/jmhannon/ > > 42,11.90N,91,39.26W > > WB0TXL > > -- > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 4 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Modified sound card and datalogging and geophones > > From: BOB BARNS > > Date: Fri, 22 Jul 2005 10:42:24 -0400 > > > > > > > > ChrisAtUpw@....... wrote: > > > In a message dated 22/07/2005, royb1@........... writes: > > > > > > Doug, > > > For a "ground-pinger": make a fitting to attach a > bicycle pump to > > > the > > > screw cap on a large plastic (one liter?) soda-pop > bottle. Bury the > > > bottle down to the neck (or deeper) and pump until the bottle > > > fails. (I > > > don't know how much pressure these things will stand.) > > > > > > Hi Bob, > > > > > > You could fit a car tyre type valve into the cap and use a foot > > > pump. I suspect that the bursting point will be quite temperature > > > sensitive. It might be OK to pump it up to 100 psi or more > and then jab > > > the bottle with a knife on a long handle? > > > > I agree that the bursting point would be temperature sensitive but I > > can't guess if that would be disabling. The ground temperature at one > > location should be relatively constant for successive shots although > > different location would see different temperatures. > > A jab with a knife would probably result in a slower release of > > energy (than the bursting of a bottle) and hence a smaller peak pulse. > > > > > > > > This scheme meets your criteria except the "multiple > impact" and > > > possibly the "ping instead of thump" but it's hard to beat for > cheap. > > > A glass bottle might be more ping-like but would leave a > hazardous > > > residue. > > > > > > That would need an awful lot of pressure and flying glass is very > > > dangeous. > > > > I agree. > > > > > > > > > > Another scheme:introduce a standard spark plug into a > pop-bottle > > > just > > > below the neck. Run two wires (thru a rubber stopper in > the neck or > a > > > screw cap) into the bottom of the bottle into an inch or so of > > > water..... > > > > > > Umm? How about put 1/2" of water in the bottom, a couple > of wires in > > > through the cap, add a teaspoonful of calcium carbide, shake > and wait a > > > few minutes. Stand well clear and put a spark between the > wires to fire > > > the gas mixture? > > > > > > This sort of device is used in agricultural bird scarers and they > > > produce a bang which can be heard for a mile or so. It might well be > > > possible to adapt one for seismology? > > > > The carbide idea has some charm (I have a carbide cannon) but careful > > control of the acetylene-air ratio would be necessary to achieve a > > detonation. Electrolysis of water automatically insures stoichiometry. > > > > > > > > Alternatively, equip your self with some balloons, fill them with > > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > > suggest setting the gas torch burning with the correct flame > shape, wipe > > > out the flame and then fill the balloon? A local school kid did this > > > with one of the 3 ft weather balloons in is father's garage many years > > > ago. He removed all the nearby windows for about 100 yards..... > > > > Again, stoichiometry would require careful control of gas-air ratio. > > Also, balloons are harder to bury than bottles. > > I can see that a 3 ft balloon is a good choice for window removal. > > Bob > > > > > > > > Regards, > > > > > > Chris Chapman > > > > > > > > > __________ NOD32 1.1175 (20050721) Information __________ > > > > > > This message was checked by NOD32 antivirus system. > > > http://www.eset.com > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 5 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: RE: Bruce Bolt has died > > From: "Kareem at HeyJooJoo" > > Date: Fri, 22 Jul 2005 08:22:10 -0700 > > > > I unfortunately never had the chance to meet him but would have > liked to. > I > > believe all of our libraries owe quite a bit of gratitude to him for his > > contribution of writings and research. > > > > I recalled when the Newcastle quake hit Australia some time > following our > > Loma Prieta Quake, he was interviewed about how rare it was to > see a M5.6 > > quake in that part of Australia. He referenced how his parents or > > grandparents only talked of one strong quake in Australia. I > guess that's > > where he grew up as a child? > > > > > > Kareem > > > > -----Original Message----- > > From: Dave Nelson [mailto:davenn@................ > > Sent: Friday, July 22, 2005 3:26 AM > > To: psn-l@.............. > > Subject: Re: Bruce Bolt has died > > > > At 02:50 AM 22/07/2005 -0700, you wrote: > > >All, > > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > > >opportunity to meet him at a local conference a few years ago. > > >Regards, > > >Larry Cochrane > > >Redwood City, PSN > > > > ohhhh wow :( what a sad loss to family, friends and associates, > > my condolences to all > > > > I met Bruce in the mid 1990's when he visited Otago > university, Dunedin, > > NZ where I did my geology degree. Bruce did a couple of guest speaker > talks > > ... one was on the response of the golden gate bridge to quakes > > > > It was so good to meet the man that really brought seismology home to me > > during the late ' 70's and ' 80's through his publications. > > > > thanks Bruce > > > > Dave Nelson > > Sydney, Oz > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with the > body of the > > message (first line only): unsubscribe See > > http://www.seismicnet.com/maillist.html for more information. > > > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 6 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Modified sound card and datalogging and geophones > > From: ChrisAtUpw@....... > > Date: Fri, 22 Jul 2005 13:46:30 EDT > > > > > > -------------------------------1122054390 > > Content-Type: text/plain; charset="US-ASCII" > > Content-Transfer-Encoding: 7bit > > > > In a message dated 22/07/2005, royb1@........... writes: > > > > The carbide idea has some charm (I have a carbide cannon) but careful > > control of the acetylene-air ratio would be necessary to achieve a > > detonation. Electrolysis of water automatically insures stoichiometry. > > Hi Bob, > > > > Agreed, but have you worked out how long it would take to get > sufficient > > H2 and O2 by electrolysis and the number of amp hours required? > > You would need inert electrodes in the water + lime soda? > > > > You know the volume of the bottle and hence the volume of > oxygen. You > > now need to weigh out the right amount of CaC2, tip it in the > bottle and > wait > > till it stops fizzling. It would probably be good enough? > > > > > Alternatively, equip your self with some balloons, fill them with > > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > > suggest setting the gas torch burning with the correct flame shape, > wipe > > > out the flame and then fill the balloon? > > > > Again, stoichiometry would require careful control of gas-air ratio. > > Also, balloons are harder to bury than bottles. > > > > > > > > The way my mind works, I was thinking of using sausage shaped balloons > blown > > up inside a thin cardboard tube. If you light the acetylene flame and > adjust > > the O2 to get a cylindrical blue centre, you have the correct > gas ratio. > You > > then push the flame onto a cold flat surface to snuff it out > and use the > > nozzle to fill the balloon? > > > > This should work OK. It gets around having to have a license to > handle > > explosives. > > > > Regards, > > > > Chris Chapman > > > > -------------------------------1122054390 > > Content-Type: text/html; charset="US-ASCII" > > Content-Transfer-Encoding: quoted-printable > > > > > > > > charset=3DUS-ASCII"> > > > > FONT-FAMILY:=20= > > Arial"=20 > > bottomMargin=3D7 leftMargin=3D7 topMargin=3D7 rightMargin=3D7> id=3Drol= > > e_document=20 > > face=3DArial color=3D#000000 size=3D2> > >

In a message dated 22/07/2005, royb1@........... writes:

> > > style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px > solid"><= > > FONT=20 > > style=3D"BACKGROUND-COLOR: transparent" face=3DArial > color=3D#000000=20 > > size=3D2> The carbide idea has some charm (I have > a carbide > ca= > > nnon)=20 > > but careful
control of the acetylene-air ratio would be necessary > to=20 > > achieve a
detonation. Electrolysis of water automatically > insure= > > s=20 > > stoichiometry. > >

Hi Bob,

> >

Agreed, but have you worked out how long it > wou= > > ld=20 > > take to get sufficient H2 and O2 by electrolysis and the number of amp > hours= > > =20 > > required?

> >

You would need inert electrodes in > the water > +=20= > > lime=20 > > soda?

> >

color=3D#000= > > 000=20 > > size=3D2>    You know the volume of the bottle and > hence= > > the=20 > > volume of oxygen. You now need to weigh out the right amount of > CaC2, tip > it= > > in=20 > > the bottle and wait till it stops fizzling. It would probably be good > enough= > > ?=20 > >

>    Alternatively, equip your self > with some=20 > > balloons, fill them with
> acetylene + oxygen and apply a glowing > fus= > > e or=20 > > cigarette? I
> suggest setting the gas torch burning with the > correct= > > =20 > > flame shape, wipe
> out the flame and then fill the=20 > > balloon?

   Again, stoichiometry would require > carefu= > > l=20 > > control of gas-air ratio.
Also, balloons are harder to bury > than=20 > > bottles.

> >

The way my mind works, I was thinking of=20 > > using sausage shaped balloons blown up inside a thin > cardboard tube. > If= > > you=20 > > light the acetylene flame and adjust the O2 to get > a cylindrical=20 > > blue centre, you have the correct gas ratio. You then push > the flame > on= > > to=20 > > a cold flat surface to snuff it out and use the nozzle to > fill the=20 > > balloon?

> >

This should work OK. It gets > around having to > h= > > ave=20 > > a license to handle explosives.

> >

Regards,

> >

Chris Chapman

> > > > -------------------------------1122054390-- > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 7 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Modified sound card and datalogging and geophones > > From: "James Hannon" > > Date: Fri, 22 Jul 105 12:56:29 CDT > > > > Just about any mixture of acetylene and air or oxygen will > detonate. Under > the right conditions pure acetylene will detonate. Last year I filled a > small (6 inch dia filled) ballon with acetylene and oxygen with > the correct > mixture and set it off. You really do not want to be anywhere near when it > goes off! My ears were ringing for hours and I could feel the > pressure wave > push my pant legs back. Problem is that I am not sure how you would couple > this explosion into the ground. Put on the surface the force would just > reflect off the ground. So it would have to be buried. There is also a > safety issue -- any tiny static charge on the ballon would set off the > explosion and easily hurt someone. > > Jim Hannon > > > > ---------- Original Message ---------------------------------- > > From: ChrisAtUpw@....... > > Reply-To: psn-l@.............. > > Date: Fri, 22 Jul 2005 13:46:30 EDT > > > > >In a message dated 22/07/2005, royb1@........... writes: > > > > > >The carbide idea has some charm (I have a carbide cannon) but careful > > >control of the acetylene-air ratio would be necessary to achieve a > > >detonation. Electrolysis of water automatically insures > stoichiometry. > > >Hi Bob, > > > > > > Agreed, but have you worked out how long it would take to get > sufficient > > >H2 and O2 by electrolysis and the number of amp hours required? > > > You would need inert electrodes in the water + lime soda? > > > > > > You know the volume of the bottle and hence the volume of oxygen. > You > > >now need to weigh out the right amount of CaC2, tip it in the > bottle and > wait > > >till it stops fizzling. It would probably be good enough? > > > > > >> Alternatively, equip your self with some balloons, fill them with > > >> acetylene + oxygen and apply a glowing fuse or cigarette? I > > >> suggest setting the gas torch burning with the correct flame shape, > wipe > > >> out the flame and then fill the balloon? > > > > > >Again, stoichiometry would require careful control of gas-air ratio. > > >Also, balloons are harder to bury than bottles. > > > > > > > > > > > >The way my mind works, I was thinking of using sausage shaped balloons > blown > > >up inside a thin cardboard tube. If you light the acetylene flame and > adjust > > >the O2 to get a cylindrical blue centre, you have the correct > gas ratio. > You > > >then push the flame onto a cold flat surface to snuff it out > and use the > > >nozzle to fill the balloon? > > > > > > This should work OK. It gets around having to have a license to > handle > > >explosives. > > > > > > Regards, > > > > > > Chris Chapman > > > > > > > > -- > > Jim Hannon > > http://www.fmtcs.com/web/jmhannon/ > > 42,11.90N,91,39.26W > > WB0TXL > > -- > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 8 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: RE: Modified sound card and datalogging and geophones > > From: "Wayne Francis" > > Date: Fri, 22 Jul 2005 11:22:23 -0700 > > > > Just as an aside, some of these contraptions sound a little like my > > son's potato cannon. Along with the spark, it used Aqua-net hairspray as > > the volatile substance (would auto starter spray work?). Pretty good > > bang to fire that potato. They used PVC, but build one out of 2 inch > > steel pipe, give it a squirt, set it off with a sparker (they were > > experimenting with piezo, ie. barbeque striker). Might work. > > Wayne Francis > > Ojai, CA > > > > -----Original Message----- > > From: psn-l-request@.............. [mailto:psn-l-request@............... > > On Behalf Of BOB BARNS > > Sent: Friday, July 22, 2005 7:42 AM > > To: psn-l@.............. > > Subject: Re: Modified sound card and datalogging and geophones > > > > > > > > ChrisAtUpw@....... wrote: > > > In a message dated 22/07/2005, royb1@........... writes: > > > > > > Doug, > > > For a "ground-pinger": make a fitting to attach a bicycle pump > > to > > > the > > > screw cap on a large plastic (one liter?) soda-pop bottle. Bury > > the > > > bottle down to the neck (or deeper) and pump until the bottle > > > fails. (I > > > don't know how much pressure these things will stand.) > > > > > > Hi Bob, > > > > > > You could fit a car tyre type valve into the cap and use a foot > > > pump. I suspect that the bursting point will be quite temperature > > > sensitive. It might be OK to pump it up to 100 psi or more and then > > jab > > > the bottle with a knife on a long handle? > > > > I agree that the bursting point would be temperature sensitive but I > > > > can't guess if that would be disabling. The ground temperature at one > > location should be relatively constant for successive shots although > > different location would see different temperatures. > > A jab with a knife would probably result in a slower release of > > energy (than the bursting of a bottle) and hence a smaller peak pulse. > > > > > > > > This scheme meets your criteria except the "multiple impact" > > and > > > possibly the "ping instead of thump" but it's hard to beat for > > cheap. > > > A glass bottle might be more ping-like but would leave a > > hazardous > > > residue. > > > > > > That would need an awful lot of pressure and flying glass is very > > > dangeous. > > > > I agree. > > > > > > > > > > Another scheme:introduce a standard spark plug into a > > pop-bottle > > > just > > > below the neck. Run two wires (thru a rubber stopper in the neck > > or a > > > screw cap) into the bottom of the bottle into an inch or so of > > > water..... > > > > > > Umm? How about put 1/2" of water in the bottom, a couple of wires > > in > > > through the cap, add a teaspoonful of calcium carbide, shake and wait > > a > > > few minutes. Stand well clear and put a spark between the wires to > > fire > > > the gas mixture? > > > > > > This sort of device is used in agricultural bird scarers and they > > > produce a bang which can be heard for a mile or so. It might well be > > > possible to adapt one for seismology? > > > > The carbide idea has some charm (I have a carbide cannon) but careful > > > > control of the acetylene-air ratio would be necessary to achieve a > > detonation. Electrolysis of water automatically insures stoichiometry. > > > > > > > > Alternatively, equip your self with some balloons, fill them with > > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > > suggest setting the gas torch burning with the correct flame shape, > > wipe > > > out the flame and then fill the balloon? A local school kid did this > > > with one of the 3 ft weather balloons in is father's garage many years > > > > > ago. He removed all the nearby windows for about 100 yards..... > > > > Again, stoichiometry would require careful control of gas-air ratio. > > Also, balloons are harder to bury than bottles. > > I can see that a 3 ft balloon is a good choice for window removal. > > Bob > > > > > > > > Regards, > > > > > > Chris Chapman > > > > > > > > > __________ NOD32 1.1175 (20050721) Information __________ > > > > > > This message was checked by NOD32 antivirus system. > > > http://www.eset.com > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 9 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: RE: Bruce Bolt has died > > From: "felipe luevanos luevanos" > > Date: Fri, 22 Jul 2005 18:27:16 +0000 > > > > I am truly sorry, do you know when this happened? > > > > Felipe Luevanos. > > > > >From: Larry Cochrane > > >Reply-To: psn-l@.............. > > >To: psn-l@.............. > > >Subject: Bruce Bolt has died > > >Date: Fri, 22 Jul 2005 02:50:29 -0700 > > > > > >All, > > > > > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > > >opportunity to meet him at a local conference a few years ago. > > > > > >Regards, > > >Larry Cochrane > > >Redwood City, PSN > > > > > >__________________________________________________________ > > > > > >Public Seismic Network Mailing List (PSN-L) > > > > > >To leave this list email PSN-L-REQUEST@.............. with the body of > the > > >message (first line only): unsubscribe > > >See http://www.seismicnet.com/maillist.html for more information. > > > > _________________________________________________________________ > > Express yourself instantly with MSN Messenger! Download today it's FREE! > > http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 10 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Modified sound card and datalogging and geophones > > From: Karl Cunningham > > Date: Fri, 22 Jul 2005 17:31:44 -0700 > > > > Hi All -- > > > > My son used to set off 2-liter soda bottles by putting some dry ice in > them > > and then screwing on the cap. It takes about 5 minutes for it > to build up > > enough pressure to burst the bottle, but less if the bottle is > in contact > > with the ground. I would try doing this by augering a hole in > the ground > > (or use a post-hole shovel) just large enough to fit the soda > bottle, then > > covering the hole with something solid (concrete blocks) just after the > cap > > has been screwed onto the bottle. This may be the least > expensive method > > and should produce a relatively high-frequency content. The report from > > the bottle exploding in air can be heard for over a mile and I > can attest > > that it annoys neighbors and attracts police attention. Examining a > bottle > > after the explosion, it appears the explosion happens quite > quickly. The > > bottle is opened starting from the bottom like petals of a flower, with > the > > cap at the center. > > > > I have tried blowing out an acetylene torch then feeding the gas into an > > empty container, then igniting it with a spark plug. Have gotten mixed > > results. Not sure why. > > > > I have done the "potato cannon" using ether, available at auto-parts > stores > > in aerosol cans as engine-starting fluid. After setting them off dozens > of > > times though, the results are far from uniform. Probably due to > > poorly-controlled fuel-to-air ratio. > > > > Regards, > > Karl Cunningham > > > > > > --On Friday, July 22, 2005 1:46 PM -0400 ChrisAtUpw@....... wrote: > > > > > In a message dated 22/07/2005, royb1@........... writes: > > > > > > The carbide idea has some charm (I have a carbide cannon) but careful > > > control of the acetylene-air ratio would be necessary to achieve a > > > detonation. Electrolysis of water automatically insures > stoichiometry. > > > Hi Bob, > > > > > > Agreed, but have you worked out how long it would take to get > > > sufficient H2 and O2 by electrolysis and the number of amp hours > > > required? You would need inert electrodes in the water + > lime soda? > > > > > > You know the volume of the bottle and hence the volume of oxygen. > > > You now need to weigh out the right amount of CaC2, tip it in the > > > bottle and wait till it stops fizzling. It would probably be good > > > enough? > > > > > >> Alternatively, equip your self with some balloons, fill them with > > >> acetylene + oxygen and apply a glowing fuse or cigarette? I > > >> suggest setting the gas torch burning with the correct flame shape, > > >> wipe out the flame and then fill the balloon? > > > > > > Again, stoichiometry would require careful control of gas-air ratio. > > > Also, balloons are harder to bury than bottles. > > > > > > > > > > > > The way my mind works, I was thinking of using sausage > shaped balloons > > > blown up inside a thin cardboard tube. If you light the acetylene > flame > > > and adjust the O2 to get a cylindrical blue centre, you have the > > > correct gas ratio. You then push the flame onto a cold flat > surface to > > > snuff it out and use the nozzle to fill the balloon? > > > > > > This should work OK. It gets around having to have a license to > > > handle explosives. > > > > > > Regards, > > > > > > Chris Chapman > > > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 11 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Modified sound card and datalogging and geophones > > From: BOB BARNS > > Date: Fri, 22 Jul 2005 21:06:00 -0400 > > > > > > > > ChrisAtUpw@....... wrote: > > > In a message dated 22/07/2005, royb1@........... writes: > > > > > > The carbide idea has some charm (I have a carbide cannon) but > > > careful > > > control of the acetylene-air ratio would be necessary to achieve a > > > detonation. Electrolysis of water automatically insures > stoichiometry. > > > > > > Hi Bob, > > > > > > Agreed, but have you worked out how long it would take to get > > > sufficient H2 and O2 by electrolysis and the number of amp hours > required? > > > You would need inert electrodes in the water + lime soda? > > > > Salt water and carbon electrodes would work BUT, as often happens, > > the devil is in the details. I calc. that to get 1 liter of > > oxy-hydrogen mixture reqires 10 amps for 14 mins. I think this is > > unworkable. > > The CaC2 scheme should be much better. > > > > > > You know the volume of the bottle and hence the volume of oxygen. > > > You now need to weigh out the right amount of CaC2, tip it in > the bottle > > > and wait till it stops fizzling. It would probably be good enough? > > > > > > > Alternatively, equip your self with some balloons, fill > them with > > > > acetylene + oxygen and apply a glowing fuse or cigarette? I > > > > suggest setting the gas torch burning with the correct flame shape, > wipe > > > > out the flame and then fill the balloon? > > > > > > Again, stoichiometry would require careful control of > gas-air ratio. > > > Also, balloons are harder to bury than bottles. > > > > > > The way my mind works, I was thinking of using sausage shaped > > > balloons blown up inside a thin cardboard tube. If you light the > > > acetylene flame and adjust the O2 to get a cylindrical blue > centre, you > > > have the correct gas ratio. You then push the flame onto a cold flat > > > surface to snuff it out and use the nozzle to fill the balloon? > > > > I like this method except that it requires lugging around acetylene > > and oxygen tanks. Perhaps the balloons could be filled at a central > > site and then taken into the field. > > Another thought pertinent to all these schemes: the top of the gas > > container should be some distance below ground level and dirt packed > > above the container. This provides directing the force of explosion > > into the ground rather than letting it be expended into the air. This > > is called "tamping". See > > http://www.mektonzeta.com/archive/explosives.php > > Bob > > > > > > > > This should work OK. It gets around having to have a license to > > > handle explosives. > > > > > > Regards, > > > > > > Chris Chapman > > > > > > > > > __________ NOD32 1.1176 (20050722) Information __________ > > > > > > This message was checked by NOD32 antivirus system. > > > http://www.eset.com > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 12 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Modified sound card and datalogging and geophones > > From: BOB BARNS > > Date: Fri, 22 Jul 2005 21:10:59 -0400 > > > > Wayne, > > I suspect that the propellant in the hairspray is a hydrocarbon such > > as propane. > > A propane-air mixture does not detonate; rather it burns rapidly like > > gunpowder. This would provide a longer seismic pulse than the > > detonation of hydrogen-oxygen or acetylene-air mixtures. > > Bob > > > > > > Wayne Francis wrote: > > > > > Just as an aside, some of these contraptions sound a little like my > > > son's potato cannon. Along with the spark, it used Aqua-net > hairspray as > > > the volatile substance (would auto starter spray work?). Pretty good > > > bang to fire that potato. They used PVC, but build one out of 2 inch > > > steel pipe, give it a squirt, set it off with a sparker (they were > > > experimenting with piezo, ie. barbeque striker). Might work. > > > Wayne Francis > > > Ojai, CA > > > > > > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 13 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: RE: Bruce Bolt has died > > From: Mariam Kaba-Marshall > > Date: Fri, 22 Jul 2005 18:18:49 -0700 (PDT) > > > > --0-297853181-1122081529=:48544 > > Content-Type: text/plain; charset=iso-8859-1 > > Content-Transfer-Encoding: 8bit > > > > I am truly sorry. > > > > Mariam Marshall > > > > felipe luevanos luevanos wrote: > > I am truly sorry, do you know when this happened? > > > > Felipe Luevanos. > > > > >From: Larry Cochrane > > >Reply-To: psn-l@.............. > > >To: psn-l@.............. > > >Subject: Bruce Bolt has died > > >Date: Fri, 22 Jul 2005 02:50:29 -0700 > > > > > >All, > > > > > >I just read on a newsgroup that Bruce Bolt has passed away. I had the > > >opportunity to meet him at a local conference a few years ago. > > > > > >Regards, > > >Larry Cochrane > > >Redwood City, PSN > > > > > >__________________________________________________________ > > > > > >Public Seismic Network Mailing List (PSN-L) > > > > > >To leave this list email PSN-L-REQUEST@.............. with the body of > the > > >message (first line only): unsubscribe > > >See http://www.seismicnet.com/maillist.html for more information. > > > > _________________________________________________________________ > > Express yourself instantly with MSN Messenger! Download today it's FREE! > > http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > > > MariamKMarshall > > > > > > __________________________________________________ > > Do You Yahoo!? > > Tired of spam? Yahoo! Mail has the best spam protection around > > http://mail.yahoo.com > > --0-297853181-1122081529=:48544 > > Content-Type: text/html; charset=iso-8859-1 > > Content-Transfer-Encoding: 8bit > > > >

> >

I am truly sorry.

> >

Mariam Marshall

felipe luevanos luevanos > <felicaribe5@...........> wrote:

> >

I am truly sorry, do you know when this > happened?

Felipe Luevanos.

>From: Larry Cochrane >
>Reply-To: > psn-l@..............
>To: > psn-l@..............
>Subject: Bruce Bolt has died
>Date: Fri, > 22 Jul 2005 02:50:29 -0700
>
>All,
>
>I > just read on > a newsgroup that Bruce Bolt has passed away. I had the
>opportunity > to meet him at a local conference a few years > ago.
>
>Regards,
>Larry Cochrane
>Redwood City, > PSN
>
>_______________________________________________ > __________ > _
>
>Public Seismic Network Mailing List > (PSN-L)
>
>To leave this list email > PSN-L-REQUEST@.............. > with the body of the
>message (first line only): > unsubscribe
>See http://www.seismicnet.com/maillist.html for more > > > information.

______________________________________________ > __________ > _________
Express yourself instantly with MSN Messenger! Download today > it's FREE! >
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01 > /

_ > _________________________________________________________

Public > Seismic Network Mailing List (PSN-L)

To leave this list email > PSN-L-REQUEST@.............. with
the body of the message (first line > only): unsubscribe
See http://www.seismicnet.com/maillist.html for more > information.

> >

color=#ff40ff>MariamKMarshall href="http://www.alex1mariam1.yahoo.com/">

DIV>

___ > _______________________________________________
Do You Yahoo!?
Tired > of spam? Yahoo! Mail has the best spam protection around >
http://mail.yahoo.com > > --0-297853181-1122081529=:48544-- > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 14 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Modified sound card and datalogging and geophones > > From: Gordon Couger > > Date: Sat, 23 Jul 2005 00:47:57 -0500 > > > > Bob, > > > > A propane air mixture will detonate if the mix is just right it > > is used as fuel in detonation engines. The fuel to air ration is > > lot narrower and the conditions more critical than hydrogen or > > actetyene. > > > > Gordon > > > > BOB BARNS wrote: > > > Wayne, > > > I suspect that the propellant in the hairspray is a hydrocarbon such > > > as propane. > > > A propane-air mixture does not detonate; rather it burns > rapidly like > > > gunpowder. This would provide a longer seismic pulse than the > > > detonation of hydrogen-oxygen or acetylene-air mixtures. > > > Bob > > > > > > > > > Wayne Francis wrote: > > > > > >> Just as an aside, some of these contraptions sound a little like my > > >> son's potato cannon. Along with the spark, it used Aqua-net hairspray > as > > >> the volatile substance (would auto starter spray work?). Pretty good > > >> bang to fire that potato. They used PVC, but build one out of 2 inch > > >> steel pipe, give it a squirt, set it off with a sparker (they were > > >> experimenting with piezo, ie. barbeque striker). Might work. > > >> Wayne Francis > > >> Ojai, CA > > >> > > > > > > > > > __________________________________________________________ > > > > > > Public Seismic Network Mailing List (PSN-L) > > > > > > To leave this list email PSN-L-REQUEST@.............. with the body of > > > the message (first line only): unsubscribe > > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > > > > > > > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > > | Message 15 | > > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > > Subject: Re: Bruce Bolt has died > > From: Col Lynam > > Date: Sat, 23 Jul 2005 16:38:22 +1000 > > > > This is a multi-part message in MIME format. > > --------------090006060605090302030801 > > Content-Type: text/plain; charset=us-ascii; format=flowed > > Content-Transfer-Encoding: 7bit > > > > Dear Psn BB readers > > I'd appreciate any references to any obituary for Bruce Bolt. > > I'd like to compose a small one to place in the newsletter for Aust > > earthquake Engineers Soc. > > > > Thanks all.. > > col lynam > > volunteer observor, QUAKES group, ESSCC centre, Uni of Queensland, > Australia > > > > Dave Nelson wrote: > > > > > At 02:50 AM 22/07/2005 -0700, you wrote: > > > > > >> All, > > >> I just read on a newsgroup that Bruce Bolt has passed away. I had the > > >> opportunity to meet him at a local conference a few years ago. > > >> Regards, > > >> Larry Cochrane > > >> Redwood City, PSN > > > > > > > > > ohhhh wow :( what a sad loss to family, friends and associates, > > > my condolences to all > > > > > > I met Bruce in the mid 1990's when he visited Otago university, > > > Dunedin, NZ > > > where I did my geology degree. Bruce did a couple of guest > speaker talks > > > ... one was on the response of the golden gate bridge to quakes > > > > > > It was so good to meet the man that really brought seismology > home to me > > > during the late ' 70's and ' 80's through his publications. > > > > > > thanks Bruce > > > > > > Dave Nelson > > > Sydney, Oz > > > > > > > > > __________________________________________________________ > > > > > > Public Seismic Network Mailing List (PSN-L) > > > > > > To leave this list email PSN-L-REQUEST@.............. with the body of > > > the message (first line only): unsubscribe > > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > > --------------090006060605090302030801 > > Content-Type: text/html; charset=us-ascii > > Content-Transfer-Encoding: 7bit > > > > > > > > > > content="text/html;charset=ISO-8859-1"> > > > > > > > > Dear Psn BB readers
> > I'd appreciate any references to any obituary for Bruce Bolt.
> > I'd like to compose a small one to place in the newsletter for Aust > > earthquake Engineers Soc.
> >
> > Thanks all..
> > col lynam
> > volunteer observor, QUAKES group, ESSCC centre, Uni of Queensland, > > Australia
> >
> > Dave Nelson wrote:
> >

> cite="mid5.1.0.14.1.20050722201958.01de7ce0@....................">At > > 02:50 AM 22/07/2005 -0700, you wrote: > >
> >
All, > >
> > I just read on a newsgroup that Bruce Bolt has passed away. I had the > > opportunity to meet him at a local conference a few years ago. > >
> > Regards, > >
> > Larry Cochrane > >
> > Redwood City, PSN > >
> >
> >
> > ohhhh wow :( what a sad loss to > family, friends and associates, > >
> > my condolences to all > >
> >
> > I met Bruce in the mid 1990's when he visited Otago university, > > Dunedin, NZ > >
> > where I did my geology degree. Bruce did a couple of guest speaker > > talks > >
> > ... one was on the response of the golden gate bridge to quakes > >
> >
> > It was so good to meet the man that really brought seismology home to > > me > >
> > during the late ' 70's and ' 80's through his publications. > >
> >
> > thanks Bruce > >
> >
> > Dave Nelson > >
> > Sydney, Oz > >
> >
> >
> > __________________________________________________________ > >
> >
> > Public Seismic Network Mailing List (PSN-L) > >
> >
> > To leave this list email href="mailto:PSN-L-REQUEST@..............">PSN-L-REQUEST@SEISMICNE > T.COM > with the body of > > the message (first line only): unsubscribe > >
> > See href="http://www.seismicnet.com/maillist.html">http://www.seismicn > et.com/mai > llist.html for more information. > >
> >
> >

> > > > > > > > --------------090006060605090302030801-- > > > > > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-DIGEST-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismic Energy Source From: ChrisAtUpw@....... Date: Sat, 23 Jul 2005 19:30:26 EDT In a message dated 23/07/2005, dcrice@............ writes: Doug Crice http://www.geostuff.com To remind folks of the specifications, I would like to repeat and expand them. 1) A person ought to be able to carry it around. Lets widen this out a bit to say three people max, each carrying component parts? 210 lbs? 2) It needs reasonably high frequency output (ping instead of thunk) This implies that the impact velocity needs to be high. 3) Build it for $1000-$2000 (cost, not sales price) in lots of 10 units, using commercially available and machined parts and normal labour rates. Sure costs need to be considered, but mass production does not necessarily mean producing high volumes at any one time, just the ability to produce the article rapidly with a very low batch start up cost and low overheads. 4) It should be safe, even when used by students We used to define three degrees of 'proof' for the undergraduate laboratories. Fool proof, idiot proof and student proof. If you insist on student proof, you won't even have a pedal cycle, never mind a car.... The power of an inquisitive mind to thoroughly louse things up must not be underestimated. 5) There should be no significant regulatory issues (a problem with dynamite, the perfect source) What sort of charges / energy output is involved here? What do we actually need for the surveying operations were are considering? Does the source have to be generated deep underground? We need to design machines for the jobs, NOT a universal machine. 6) Operating supplies available in third world countries. And in the developed world. 7) It needs to work better than a sledgehammer used with a seismograph that can stack multiple impacts. We could also try designing a better / different type of sledge hammer / impactor? 8) Because the source will probably be used in a repetitive fashion, it needs a reasonably fast cycle time (many seconds, not many minutes). We need to be careful here. If we specify too rapid a pulse rate, or too high an energy per pulse, we will automatically be specifying very powerful and expensive equipment. 9) The seismic signature should approximate a zero phase wavelet, which as a practical matter; means the energy prior to impact should be comparatively modest. 10) Good ground coupling is needed. In the case of a sledgehammer, a metal plate is placed on the ground as a target. In the in-hole shotgun, a hole is augured just big enough to hold the device below the soft topsoil and preferably watered. Is there any published work on the optimal shapes of ground coupling plates, flat or conical, resonant modes, mass etc? The crossbow idea is equivalent to the "elastic wave generator", powered by the large rubber band. Existing units weigh a couple of hundred pounds, but it's got me thinking about a portable version. The reason that I suggested some sort of metal spring, is that the properties of most elastomers are very time dependant. The properties of metal springs are not, apart from the physical mass / inertia of the spring. The cross-bow form allows you to continuously accelerate the projectile to a high velocity, without giving it a shock impulse. There are other mechanical linkages / principles which could be used. The larger Roman ballistas used to fire a bolt over about 500 m max. The variations on exploding bottles don't seem to meet the requirements for reasonably safe operation. Lets not rule out the principle. I am thinking of an analogy with a petrol driven rock drill, which has a linear piston striking an anvil. That is optimised for rapidly repeating blows. Here we need to redesign it for optimum performance with either a single stroke, or at most two strokes in a sequence. Maybe we could power it with bottled gas? An earlier variation was the "vacuum assisted weight drop". It had a 6 ft (2 meter) long tube about 6 inches (15 cm) in diameter with a 100 pound steel bullet inside. The bullet was pushed up with air pressure, then evacuated. When the tube was full of vacuum, it was released and accelerated by its weight and by atmospheric air pressure. At the bottom was a 100 pound anvil and plate combination pressed on the ground by the weight of the whole mechanism. With equal weights for the piston and anvil, it didn't bounce (think of that ball bearing toy). The VAWD worked reasonably well, but weighed 1000 pounds and cost over $10K 20 years ago. Using air pressure as the accelerant provided a nice signature, since the force was external to the system, though when you released the piston, it instantly lost 100 pounds of weight, providing the equivalent of a negative sledgehammer blow. If it is 6" dia, the force from air pressure will be 3^2xPix14.7 lbs = 416 lbs. Maybe they should have concentrated on the energy available from the air pressure and increased the impact velocity? It is possible to crank this force with a 10:1 chain winch. Maybe a hydraulic system? Anything much greater or several cycles per minute and you need an engine / power source to do it. 1 man gives about 0.1 HP, continuous exercise. There is an alternative operating mode, in which you extend the plunger / piston or whatever and then pump out the air from behind it? The long tube design does give a high power stroke, but a relatively low final velocity. It would be difficult to use the tube design for very high velocities, but it could be developed considerably from a 100 lb mass + a 400 lb air push ---> 44 ft / sec. Maybe one of these somewhat random ideas can developed, or will generate other ideas? Regards, Chris Chapman

In a message dated 23/07/2005, dcrice@............ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Doug=20 Crice http://www.geostuff.com

To=20 remind folks of the specifications, I would like to repeat and expand=20 them.

1) A person ought to be able to carry it=20 around.

Lets widen this out a bit to say three people m= ax,=20 each carrying component parts? 210 lbs?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>2) It=20 needs reasonably high frequency output (ping instead of=20 thunk)

This implies that the impact velocity needs to=20= be=20 high.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>3) Build=20 it for $1000-$2000 (cost, not sales price) in lots of 10 units,
using=20 commercially available and machined parts and normal labour=20 rates.

Sure costs need to be considered, but mass=20 production does not necessarily mean producing high volumes at any one time,= =20 just the ability to produce the article rapidly with a very low batch start=20= up=20 cost and low overheads.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>4) It=20 should be safe, even when used by students

We used to define three degrees of 'proof' for=20= the=20 undergraduate laboratories. Fool proof, idiot proof and student proof. If yo= u=20 insist on student proof, you won't even have a pedal cycle, never mind a car= .....=20 The power of an inquisitive mind to thoroughly louse things up must not be=20 underestimated.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>5) There=20 should be no significant regulatory issues (a problem with dynamite, the=20 perfect source)

What sort of charges / energy output is involve= d=20 here? What do we actually need for the surveying operations were are=20 considering? Does the source have to be generated deep underground?

We need to design machines for the=20 jobs, NOT a universal machine.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>6)=20 Operating supplies available in third world countries.

And in the developed world.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>7) It=20 needs to work better than a sledgehammer used with a seismograph that
c= an=20 stack multiple impacts.

We could also try designing a better / differen= t=20 type of sledge hammer / impactor?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>8)=20 Because the source will probably be used in a repetitive fashion, it
ne= eds=20 a reasonably fast cycle time (many seconds, not many=20 minutes).

We need to be careful here. If we specify = too=20 rapid a pulse rate, or too high an energy per pulse, we will automatica= lly=20 be specifying very powerful and expensive equipment.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>9) The=20 seismic signature should approximate a zero phase wavelet, which as=20 a
practical matter; means the energy prior to impact should be=20 comparatively
modest.
10) Good ground coupling is needed. In the cas= e of=20 a sledgehammer, a metal
plate is placed on the ground as a target. In t= he=20 in-hole shotgun, a hole is
augured just big enough to hold the device b= elow=20 the soft topsoil and
preferably watered.

Is there any published work on the optimal shap= es=20 of ground coupling plates, flat or conical, resonant modes, mass etc? <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 crossbow idea is equivalent to the "elastic wave generator", powered bythe=20 large rubber band. Existing units weigh a couple of hundred pounds,=20 but
it's got me thinking about a portable version.

The reason that I suggested some sort of metal=20 spring, is that the properties of most elastomers are very time dependant. T= he=20 properties of metal springs are not, apart from the physical mass / inertia=20= of=20 the spring. The cross-bow form allows you to continuously accelerate the=20 projectile to a high velocity, without giving it a shock impulse. There are=20 other mechanical linkages / principles which could be used. The larger=20 Roman ballistas used to fire a bolt over about 500 m max.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 variations on exploding bottles don't seem to meet the requirements for=20 reasonably safe operation.

Lets not rule out the principle. I am thin= king=20 of an analogy with a petrol driven rock drill, which has a linear piston=20 striking an anvil. That is optimised for rapidly repeating blows. Here we ne= ed=20 to redesign it for optimum performance with either a single stroke, or at mo= st=20 two strokes in a sequence. Maybe we could power it with bottled gas?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>An=20 earlier variation was the "vacuum assisted weight drop". It had a 6 ft=20 (2
meter) long tube about 6 inches (15 cm) in diameter with a 100 pound= =20 steel
bullet inside. The bullet was pushed up with air pressure, then=20 evacuated.
When the tube was full of vacuum, it was released and=20 accelerated by its
weight and by atmospheric air pressure. At the botto= m=20 was a 100 pound anvil
and plate combination pressed on the ground by th= e=20 weight of the whole
mechanism. With equal weights for the piston and an= vil,=20 it didn't bounce
(think of that ball bearing toy). The VAWD worked=20 reasonably well, but
weighed 1000 pounds and cost over $10K 20 years ag= o.=20 Using air pressure as
the accelerant provided a nice signature, since t= he=20 force was external to
the system, though when you released the piston,=20= it=20 instantly lost 100
pounds of weight, providing the equivalent of a nega= tive=20 sledgehammer blow.

If it is 6" dia, the force from air press= ure=20 will be 3^2xPix14.7 lbs =3D 416 lbs.

Maybe they should have concentrated on the ener= gy=20 available from the air pressure and increased the impact velocity?

It is possible to crank this force with a 1= 0:1=20 chain winch. Maybe a hydraulic system? Anything much greater or several cycl= es=20 per minute and you need an engine / power source to do it. 1 man gives=20 about 0.1 HP, continuous exercise. There is an alternative operating mode, i= n=20 which you extend the plunger / piston or whatever and then pump out the= air=20 from behind it?

The long tube design does give a high power= =20 stroke, but a relatively low final velocity. It would be difficult to use th= e=20 tube design for very high velocities, but it could be developed considerably= =20 from a 100 lb mass + a 400 lb air push ---> 44 ft / sec.

Maybe one of these somewhat random ideas can=20 developed, or will generate other ideas?

Regards,

Chris Chapman

Subject: RE: Modified sound card and datalogging and geophones From: "Timothy Carpenter" GeoDynamics@....... Date: Sat, 23 Jul 2005 19:53:59 -0400 John, The same thought crossed my mind while reading through the various = comments and ideas. However, I view the information as potentially quite valuable = in my line of work (geotechnical engineering and vibration analyses). = Although I detest the potential that some nitwit might do harm with information gleaned from this or any other free information source, I refuse to = forfeit the free exchange of ideas. When we restrict information flow, they win. = So, I must extend my disagreement with your worthy comments. -Tim- =20 Timothy Carpenter, P.E., Pres., GeoDynamics Consultants, Inc. 5043 Whitlow Ct. Commerce Twp., Mi 48382 248-363-4529 (voice & fax) 248-766-1629 (cell) geodynamics@........... (primary) geodynamics@....... (secondary) =20 =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of John or Jan Lahr Sent: Saturday, July 23, 2005 10:56 AM To: psn-l@.............. Subject: Re: Modified sound card and datalogging and geophones =20 Given today's world, lets not make the PSN list one more place to learn about bomb making! This has been an interesting topic, but I think it's quite a tangent from amateur seismology for most of us. Just my opinion, added with all due respect to all of the interesting suggestions that have been contributed. Cheers, John ##################################/ John C. Lahr #################################/ Emeritus Seismologist=20 ################################/ U.S. Geological Survey =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D/ Geologic Hazards Team ##############################/ Golden, Colorado #############################//############################## ############################//############################### PO Box 548 = /################################ Corvallis, Oregon 97339 /################################## Phone: (541) 758-2699 = /=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D Cell: (541) 740-4844 /################################### Fax: (928) 569-0113 /################################## jjpub@........ /#################################### http://jclahr.com/science/

John,

The same thought crossed my mind = while reading through the various comments and ideas. However, I view the = information as potentially quite valuable in my line of work (geotechnical = engineering and vibration analyses). Although I detest the potential that some nitwit = might do harm with information gleaned from this or any other free information = source, I refuse to forfeit the free exchange of ideas. When we restrict = information flow, they win. So, I must extend my disagreement with your worthy = comments.

-Tim-

Timothy Carpenter, P.E., = Pres.,
GeoDynamics Consultants, Inc.
5043 Whitlow = Ct.
Commerce Twp., Mi 48382
248-363-4529 (voice & fax)
248-766-1629 (cell)
geodynamics@........... = (primary)
geodynamics@....... = (secondary)

-----Original = Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of John or Jan Lahr
Sent: Saturday, July 23, 2005 10:56 = AM
To: = psn-l@..............
Subject: Re: Modified = sound card and datalogging and geophones

Given today's world, lets not make the PSN = list one more place to learn about bomb making! This has been an = interesting topic, but I think it's quite a tangent from amateur seismology for most = of us.

Just my opinion, added with all due respect to all of the interesting suggestions that have been contributed.

Cheers,
John

##########################= ########/ John C. Lahr
#################################/ Emeritus Seismologist
################################/ U.S. Geological Survey
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D/ Geologic Hazards Team
##############################/ Golden, Colorado
#############################//##############################
############################//###############################
            &= nbsp;           &n= bsp;    PO Box = 548 /################################
             = Corvallis, = Oregon 97339 /##################################
             = Phone: (541) 758-2699 = /=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D
            &= nbsp; Cell: (541) 740-4844 /###################################
             = Fax: (928) 569-0113 /##################################
            &= nbsp;       jjpub@........ /####################################
            &= nbsp;           &n= bsp;        http://jclahr.com/science/

Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Sat, 23 Jul 2005 19:40:04 -0500 Bob, I was pretty sure it could happen in open air but it was a mix of propane, butane and ethane not just propane as I remembered from: http://archive.theeagle.com/region/localregional/042802explosionsider.htm. Ethane will detonate in air and probably set off some of the other gases. I a valley full of the stuff there would be all kinds of concentrations and once a detonation started I expect it would trigger every thing in its reach that would detonate and burn most of the rest. Not something I would want to see. But for a 2 liter bottle oxygen and acetylene flood filled from a torch sounds like the most practical solution. If you want a safer one put the exact amount of carbide in a gelatin capsule to release the amount of C2H2 for the air in the bottle and drop it in after the bottle is almost buried, screw the lid with the igniter on and finish the burial and go on to the next one. BOB BARNS wrote: > Gordon, > The little I have read ( http://www.aardvark.co.nz/pjet/pde.shtml ) > suggests that something other than the correct fuel-air ratio is needed > to cause detonation. > Bob > > > Gordon Couger wrote: > >> Bob, >> >> A propane air mixture will detonate if the mix is just right it is >> used as fuel in detonation engines. The fuel to air ration is lot >> narrower and the conditions more critical than hydrogen or actetyene. >> >> Gordon > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Seismic Energy Source From: Gordon Couger gcouger@.......... Date: Sat, 23 Jul 2005 20:28:26 -0500 Doug, When you put in the regular air freight part you eliminate any explosives but on site generated oxygen and hydrogen. When you set the cost limit at $2,000 you eliminate any drop hammers or devices weighing at 500 to 1,000 pounds unless they are extremely simple. If you really want a device in that price range I think you should reconsider using a 2 or 3 liter bottle with enough water in it to discover a coating around a bit of calcium carbide and generate C2H2 when it is dropped in the bottle after the bottles is set in the ground and covered up to the cap by unskilled labor. The Forman or Preston in charge loads the calcium carbide pellet that is coated in something to keep it from generating C2H2 for a few minutes and finish covering it up and wire it for firing. There needs to be a pressure sensor in the lid of the bottle to let you know when it has enough C2H2 to give the desired results. I think it can be done as safely but you can't ship calcium carbide air freight. But it is a lot cheaper than you price range. I don't think a kinetic device that put out and absorb the energy of sledge hammer over and over can be made for $2,000 with out an explosive component. I have seen first hand what a sledge hammer can do. If you don't want explosives I think you may be suck with a sledge hammer with a #2,000 cost limit. Gordon Doug Crice wrote: > > Doug Crice http://www.geostuff.com > Wireless Seismic http://www.wirelessSeismic.com > 12996 Somerset Drive phone 1-530-274-4445 > Grass Valley, CA 95945 USA fax 1-530-274-4446 > > I have greatly enjoyed this discourse on a better exploration seismic > source, and look forward to more ideas. To kind of remind folks of the > specifications, I would like to repeat and expand them. > > 1) A person ought to be able to carry it around (and be air mobile by > regular air freight). > 2) It needs reasonably high frequency output (ping instead of thunk) > 3) Build it for $1000-$2000 (cost, not sales price) in lots of 10 units, > using commercially available and machined parts and normal labor rates. > 4) It should be safe, even when used by students > 5) There should be no significant regulatory issues (a problem with > dynamite, the perfect source) > 6) Operating supplies available in third world countries. > 7) It needs to work better than a sledgehammer used with a seismograph that > can stack multiple impacts. > 8) Because the source will probably be used in a repetitive fashion, it > needs a reasonably fast cycle time (many seconds, not many minutes). > 9) The seismic signature should approximate a zero phase wavelet, which as a > practical matter; means the energy prior to impact should be comparatively > modest. > 10) Good ground coupling is needed. In the case of a sledgehammer, a metal > plate is placed on the ground as a target. In the in-hole shotgun, a hole is > augured just big enough to hold the device below the soft topsoil and > preferably watered. > > The crossbow idea is equivalent to the "elastic wave generator", powered by > the large rubber band. Existing units weigh a couple of hundred pounds, but > it's got me thinking about a portable version. > > The variations on exploding bottles don't seem to meet the requirements for > reasonably safe operation. Sure, a careful user would be safe, but we are > talking about students and third-world laborers. > > An earlier variation was the "vacuum assisted weight drop". It had a 6 ft (2 > meter) long tube about 6 inches (15 cm) in diameter with a 100 pound steel > bullet inside. The bullet was pushed up with air pressure, then evacuated. > When the tube was full of vacuum, it was released and accelerated by its > weight and by atmospheric air pressure. At the bottom was a 100 pound anvil > and plate combination pressed on the ground by the weight of the whole > mechanism. With equal weights for the piston and anvil, it didn't bounce > (think of that ball bearing toy). The VAWD worked reasonably well, but > weighed 1000 pounds and cost over $10K 20 years ago. Using air pressure as > the accelerant provided a nice signature, since the force was external to > the system, though when you released the piston, it instantly lost 100 > pounds of weight, providing the equivalent of a negative sledgehammer blow. > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: "Charles R. Patton" charles.r.patton@........ Date: Sat, 23 Jul 2005 18:34:09 -0700 Earlier someone mentioned the idea of pre-filling some balloons with oxygen/acetylene. DON'T. You have small bombs now that are extremely sensitive to ESD. Small spark, whole tamale goes off in your face, trunk, whatever. Spark so easy as most likely using plastic, rubber, etc, that is not ESD treated. Even in the open, you're looking for trouble. My two cents. Charles Patton > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Sat, 23 Jul 2005 23:25:14 EDT In a message dated 24/07/2005, charles.r.patton@........ writes: Earlier someone mentioned the idea of pre-filling some balloons with oxygen / acetylene. DON'T. You have small bombs now that are extremely sensitive to ESD. Small spark, whole tamale goes off in your face, trunk, whatever. Spark so easy as most likely using plastic, rubber, etc, that is not ESD treated. Even in the open, you're looking for trouble. Hi Charles, Is this advice the result of actual experiments trying to detonate C2H2 / O2 mixtures, or is it just general prudent advice without any experimental testing? Please send me the reference. We did some experiments trying to set off H2 / O2 mixtures many years ago and found that the mixture seemed much more difficult to ignite than we had expected. We were working both with gas mixtures and also with pastes of solid O2 in liquid H2, which could potentially give a very serious explosion. We were not able to ignite the mixtures with static charge found on a hair comb or by rubbing a balloon with fur. A high energy spark plug gave reliable ignition as did sparks from the an energetic 'tesla sources. Can you give a reference to look up for the enegry dischage which will produce ignition C2H2 and O2 mixtures pleae? Regards, Chris

In a message dated 24/07/2005, charles.r.patton@........ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Earlier=20 someone mentioned the idea of pre-filling some balloons with oxygen /=20 acetylene. DON'T. You have small bombs now that are extremely=20 sensitive to ESD. Small spark, whole tamale goes off in your face,=20 trunk, whatever. Spark so easy as most likely using plastic, rubber,=20= etc,=20 that is not ESD treated. Even in the open, you're looking for=20 trouble.

Hi Charles,

Is this advice the result of actual= =20 experiments trying to detonate C2H2 / O2 mixtures, or is it just=20 general prudent advice without any experimental testing?=20 Please send me the reference.

We did some experiments trying to set off&n= bsp;=20 H2 / O2 mixtures many years ago and found that the mixture seemed much=20= more=20 difficult to ignite than we had expected. We were working both with gas mixt= ures=20 and also with pastes of solid O2 in liquid H2, which could potentially=20= give=20 a very serious explosion. We were not able to ignite the mixtures with stati= c=20 charge found on a hair comb or by rubbing a balloon with fur. A high=20 energy spark plug gave reliable ignition as did sparks from the an= =20 energetic 'tesla sources.

Can you give a reference to look up for the= =20 enegry dischage which will produce ignition C2H2 and O2 mixtures pleae?

Regards,

Chris

Subject: Re: Modified sound card and datalogging and geophones From: Gordon Couger gcouger@.......... Date: Sun, 24 Jul 2005 01:08:15 -0500 Chris, C2H2 is a lot less stable than most gases. I have seen the results of a spontaneous explosion of a C2H2 generator that the fool I sold it to ran at 35 PSI. Fortunately no one was in the shop when it blew up and white washed everthing in the place. It wasn't a very violent explosion but it made a pretty good noise and the flying parts of the generator could have killed anyone in the room. At less than 25 psi it is a lot better behaved but it can form very unstable compounds with copper. http://www.ab.ust.hk/sepo/chem_info/Shock%20and%20Explosive%20Chemical.htm If you play with don't use copper wire for the igniter if is in contact with the gas repeatedly or for more than a few seconds. Acetylene is great gas to work with and is nice because you can carry it around in the form of calcium carbide to make as much as you when ever you need it. Unfortunately the apparatus for don't it by its nature and the nature of Acetylene are incompatible with modern safety standards. Gordon ChrisAtUpw@....... wrote: > In a message dated 24/07/2005, charles.r.patton@........ writes: > > Earlier someone mentioned the idea of pre-filling some balloons with > oxygen / acetylene. DON'T. You have small bombs now that are > extremely sensitive to ESD. Small spark, whole tamale goes off in > your face, trunk, whatever. Spark so easy as most likely using > plastic, rubber, etc, that is not ESD treated. Even in the open, > you're looking for trouble. > > Hi Charles, > > Is this advice the result of *actual experiments* trying to detonate > C2H2 / O2 mixtures, or is it just general prudent advice *without any > experimental testing?* *Please send me the reference. * > We did some experiments trying to set off H2 / O2 mixtures many > years ago and found that the mixture seemed much more difficult to > ignite than we had expected. We were working both with gas mixtures and > also with pastes of solid O2 in liquid H2, which could potentially give > a very serious explosion. We were not able to ignite the mixtures with > static charge found on a hair comb or by rubbing a balloon with fur. > A high energy spark plug gave reliable ignition as did sparks from the > an energetic 'tesla sources. > > Can you give a reference to look up for the enegry dischage which > will produce ignition C2H2 and O2 mixtures pleae? > > Regards, > > Chris > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Researchers Track Underwater Noise Generated by December 26 Earthquake From: Mark Robinson mark.robinson@............... Date: Sun, 24 Jul 2005 18:41:39 +1200 People may be interested in http://www.ldeo.columbia.edu/news/2005/07_20_05.htm : > The Sound of a Distant Rumble: > Researchers Track Underwater Noise Generated by December 26 Earthquake > > When the sea floor off the coast of Sumatra split on the morning of December 26, 2004, it took days to measure the full extent of the rupture. Recently, researchers at Columbia University's Lamont-Doherty Earth Observatory analyzed recordings of the underwater sound produced by the magnitude 9.3 earthquake. Their unique approach enabled them to track the rupture as it moved along the Sumatra-Andaman Fault, raising the possibility that scientists could one day use the method to track underwater earthquakes in near real time and opening new avenues in seismologic research. > > "We were able to constrain some details such as the speed and duration of the rupture more accurately than traditional seismic methods," said Maya Tolstoy, a Doherty Research Scientist and lead author of the study. "Moreover, we found the earthquake happened in two distinct phases, with faster rupture to the south and slower to the north, almost as if there were two back-to-back events." The study appears in the July/August edition of Seismological Research Letters. .... (slashdot pointed to this today : http://science.slashdot.org/article.pl?sid=05/07/23/2120242&tid=14 ) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Researchers Track Underwater Noise Generated by December 26 Earthquake From: John Popelish jpopelish@........ Date: Sun, 24 Jul 2005 10:15:31 -0400 Mark Robinson wrote: > People may be interested in > > http://www.ldeo.columbia.edu/news/2005/07_20_05.htm : > >> The Sound of a Distant Rumble: >> Researchers Track Underwater Noise Generated by December 26 Earthquake (snip) The mp3 file of the sound in this article is a compact way to store the 10X speeded up sound, but if you want a version that does not discard much of the inaudible content, there is a wav file of this data available at: http://www.ldeo.columbia.edu/~tolstoy/research/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Geophones From: Mike Speed mike8s2@......... Date: Sun, 24 Jul 2005 10:14:46 -0700 (PDT) Are you guys absolutely sure the best source for geophones is Larry's? I find his a bit spendy - I bought some others for about ten dollars apiece - they worked fine. One was lost and the other I destroyed when I tried to convert in into a capacitance-type detector. Please advise. Greg __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Geophones From: "Doug Crice" dcrice@............ Date: Sun, 24 Jul 2005 13:45:03 -0700 When I said Larry's were the best choice, I thought you were recording earthquakes, not doing exploration seismic. For earthquakes, you need lower natural frequencies and 3-component in a triax package. For exploration, you need something higher, maybe 10 to 28 Hz in what we call a "land case" with a spike. New, they are about $30 for the basic element and $60 in a case with leads attached. Naturally, they are cheaper used, but you have to scratch around. If they are oil exploration surplus, they come in multiple phones wired in series parallel (designed to filter out surface waves). You can take them apart and use the individual phones. This is the cheapest source. You can find these "geophone strings" and single phones at http://www.rtclark.com/ Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophones From: Alexandr Yagodin midia@.............. Date: Mon, 25 Jul 2005 00:19:06 +0200 25/07 7:00- 9:00 (Gr. t) M 6 - 6,5 Indonezia Yagodin Alexandr ----- Original Message ----- From: "Doug Crice" To: Sent: Sunday, July 24, 2005 10:45 PM Subject: RE: Geophones > When I said Larry's were the best choice, I thought you were recording > earthquakes, not doing exploration seismic. > > For earthquakes, you need lower natural frequencies and 3-component in a > triax package. For exploration, you need something higher, maybe 10 to 28 > Hz in what we call a "land case" with a spike. New, they are about $30 for > the basic element and $60 in a case with leads attached. > > Naturally, they are cheaper used, but you have to scratch around. If they > are oil exploration surplus, they come in multiple phones wired in series > parallel (designed to filter out surface waves). You can take them apart > and use the individual phones. This is the cheapest source. > > You can find these "geophone strings" and single phones at > http://www.rtclark.com/ > > Doug Crice http://www.geostuff.com > Wireless Seismic http://www.wirelessSeismic.com > 12996 Somerset Drive phone 1-530-274-4445 > Grass Valley, CA 95945 USA fax 1-530-274-4446 > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: "Charles R. Patton" charles.r.patton@........ Date: Sun, 24 Jul 2005 15:56:24 -0700 Chris, No, no direct experience with this mechanism of maiming myself. Have screwed up in other ways, but fortunately survived with only scars! I agree that a balloon directly is probably hard to self charge and cause problems due to Faraday cage effect and its high resistance somewhat shielding the interior from a direct spark. However it is also easy for me to imagine filling a few balloons, stuffing them into a trunk and transporting somewhere. Balloons being what they are and most times being sealed by tying off the necks, which doesn't always work so well, leaking at a slow rate. Now the trunk is filling with stoimetric acetylene/oxygen. Experimenter opens trunk, the trunk light switch sparks, and I leave the train of events from there to your imagination. I do not have the information for spark energy necessary to set off but a quick Google search at; http://www.msha.gov/alerts/hazardsofacetylene.htm yielded: "_Ease of ignition_: Acetylene is a very easy gas to ignite. In fact, the energy from a static spark capable of igniting acetylene is lower than for any other fuel gas except hydrogen. The ignition energy of acetylene in air is approximately seventeen times lower than that of methane. (Think coal mine explosions.) The static charge developed by walking across a carpet floor on a dry day can be 1700 times greater than that needed to ignite acetylene. When mixed with pure oxygen, the ignition energy of acetylene is almost 100 times lower than it is in air." This is not the description of a hard-to-ignite substance. Add to this fact the information that basically acetylene will burn from 2.5% to 81% and explosively decompose at 100%. You have some pretty potent stuff to get into trouble with. As much as I love fireworks, this is something I would think twice about before using. Years ago, somebody told me about filling a dry cleaning bag full of acetylene/O2. I don't remember the particulars, but the impression stayed with me that I didn't want to repeat his experiment. He was a long way away, and still got knocked over. Further searching at: http://yarchive.net/chem/ignition_energy.html found this table quoted: Chemical Minimum ignition energy ( mJ ) Air Oxygen Methane 0.30 0.003 Propane 0.26 0.002 n-Hexane 0.29 0.006 Acetylene 0.017 0.0002 Ethylene 0.07 0.001 Benzene 0.22 - Acetone 1.15 0.0024 Ammonia >1000 - Diethyl ether 0.20 0.0013 Methanol 0.14 - Hydrogen 0.017 0.0012 The above information comes from a US Dept of the Interior Bureau of Mines Bulletin 680. " Investigation of Fire and explosion Accidents in the Chemical, Mining, and Fuel-related Industries - A Manual. by Joseph M. Kuchta. Acetylene is shown to be six times more sensitive than H2/02 and the most sensitive in the table above. . Interesting. I find the discussion interesting and in no-way want to censor it. But I have great respect for self responsibility, and I don't wish ill will and bad results from lack of knowledge. I'm just trying to point out to anyone thinking about playing with some of these ideas -- remember young people read this list also -- that there are some important considerations that I would at least like them to consider before proceeding. I survived my experiments, but a couple could have had some very serious results, and I continue to learn something new every day, including these discussions. Regards, Chas. ChrisAtUpw@....... wrote: >In a message dated 24/07/2005, charles.r.patton@........ writes: > >Earlier someone mentioned the idea of pre-filling some balloons with oxygen >/ acetylene. DON'T. You have small bombs now that are extremely sensitive >to ESD. Small spark, whole tamale goes off in your face, trunk, whatever. >Spark so easy as most likely using plastic, rubber, etc, that is not ESD >treated. Even in the open, you're looking for trouble. >Hi Charles, > > Is this advice the result of actual experiments trying to detonate C2H2 >/ O2 mixtures, or is it just general prudent advice without any experimental >testing? Please send me the reference. > We did some experiments trying to set off H2 / O2 mixtures many years >ago and found that the mixture seemed much more difficult to ignite than we >had expected. We were working both with gas mixtures and also with pastes of >solid O2 in liquid H2, which could potentially give a very serious explosion. >We were not able to ignite the mixtures with static charge found on a hair >comb or by rubbing a balloon with fur. A high energy spark plug gave reliable >ignition as did sparks from the an energetic 'tesla sources. > > Can you give a reference to look up for the enegry dischage which will >produce ignition C2H2 and O2 mixtures pleae? > > Regards, > > Chris > > > > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophones From: ChrisAtUpw@....... Date: Sun, 24 Jul 2005 19:08:05 EDT In a message dated 24/07/2005 18:15:13 GMT Daylight Time, mike8s2@......... writes: Are you guys absolutely sure the best source for geophones is Larry's? I find his a bit spendy - I bought some others for about ten dollars apiece - they worked fine. One was lost and the other I destroyed when I tried to convert in into a capacitance-type detector. Hi Greg, I suggest that you check Ebay for geophones, seismometer and seismic. You periodically get geophones for sale, mostly 14 Hz and above. Do also check the various Ebay 'stores'. Depends what you want to do, but you can make quite a respectable geophone type sensor by sticking a weight to the centre of a piezo sounder disk. Regards, Chris Chapman

In a message dated 24/07/2005 18:15:13 GMT Daylight Time, mike8s2@yahoo= ..com=20 writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Are you=20 guys absolutely sure the best source for geophones is Larry's? I fin= d=20 his a bit spendy - I bought some others for about ten dollars apiece - the= y=20 worked fine. One was lost and the other I destroyed when I tried to=20 convert in into a capacitance-type detector.

Hi Greg,

I suggest that you check Ebay for geophones,=20 seismometer and seismic.

You periodically get geophones for sale, mostly= 14=20 Hz and above. Do also check the various Ebay 'stores'.

Depends what you want to do, but you can make q= uite=20 a respectable geophone type sensor by sticking a weight to the centre of&nbs= p;a=20 piezo sounder disk.

Regards,

Chris Chapman

Subject: Re: Modified sound card and datalogging and geophones From: John or Jan Lahr JohnJan@........ Date: Sun, 24 Jul 2005 16:15:34 -0700 At 03:56 PM 7/24/2005, you wrote: >I find the discussion interesting and in no-way want to censor it. But >I have great respect for self responsibility, and I don't wish ill >will and bad results from lack of knowledge. I'm just trying to >point out to anyone thinking about playing with some of these ideas >-- remember young people read this list also -- that there are some >important considerations that I would at least like them to consider >before proceeding. I would second this. When I was at Rensselaer Polytechnic Institute in the 1960's there was one student who was blind and had metal pincers for hands. He had been experimenting with explosions. Yours, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Modified sound card and datalogging and geophones From: "Kareem at HeyJooJoo" system98765@............. Date: Sun, 24 Jul 2005 20:01:32 -0700 Are there ever any long period sensors available? Seems like the vertical ones get homes often. -----Original Message----- From: John or Jan Lahr [mailto:JohnJan@......... Sent: Sunday, July 24, 2005 4:16 PM To: psn-l@.............. Subject: Re: Modified sound card and datalogging and geophones At 03:56 PM 7/24/2005, you wrote: >I find the discussion interesting and in no-way want to censor it. But >I have great respect for self responsibility, and I don't wish ill will >and bad results from lack of knowledge. I'm just trying to point out >to anyone thinking about playing with some of these ideas >-- remember young people read this list also -- that there are some >important considerations that I would at least like them to consider >before proceeding. I would second this. When I was at Rensselaer Polytechnic Institute in the 1960's there was one student who was blind and had metal pincers for hands. He had been experimenting with explosions. Yours, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Modified sound card and datalogging and geophones From: ChrisAtUpw@....... Date: Sun, 24 Jul 2005 23:38:48 EDT In a message dated 25/07/2005, system98765@............. writes: Are there ever any long period sensors available? Seems like the vertical ones get homes often. Hi there, Most amateurs build their own Lehmans or Shackelford Gundersens. Some ex professional long period equipment is available. Some can be converted to broad band operation, but this takes constructional and electronic skills. I hope to publish a new 'bolt it together' Lehman design in the next 6 weeks. Regards, Chris Chapman

In a message dated 25/07/2005, system98765@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Are=20 there ever any long period sensors available? Seems like the vertical
o= nes=20 get homes often.

Hi there,

Most amateurs build their own Lehmans or=20 Shackelford Gundersens. Some ex professional long period equipment is availa= ble.=20 Some can be converted to broad band operation, but this takes constructional= and=20 electronic skills.

I hope to publish a new 'bolt it together' Lehm= an=20 design in the next 6 weeks.

Regards,

Chris Chapman

Subject: geophone on ebay From: BOB BARNS royb1@........... Date: Mon, 25 Jul 2005 10:19:16 -0400 Hi gang, WORKING SEISMOGRAPH SEISMIC GEOPHONE Item number: 6196172769 ends July 31 ebay provides an easy way to send questions to the seller such as what is the period. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Geophones From: "David Saum" DSaum@............ Date: Mon, 25 Jul 2005 11:37:56 -0400 > Subject: Geophones > From: Mike Speed > Date: Sun, 24 Jul 2005 10:14:46 -0700 (PDT) > > Are you guys absolutely sure the best source for > geophones is Larry's? I have found Larry's 4.5Hz geophones to be a real bargain, at least for seismic sensing. Here are teleseismic detections from the last couple of days from one of Larry's 4.5Hz horizontal geophones that is sitting on my carpeted basement office floor with a brick resting on it: 7/23/05 5.5M Nicaragua from 2,969.4km http://www.infiltec.com/seismo/050723.gif 7/24/05 7.2M Nicobar Islands from 14,722.5km http://www.infiltec.com/seismo/050724.gif Both of these plots are filtered with HP=0.03Hz and LP=1.0Hz. Ciao, Dave http://www.infiltec.com/seismo __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: System for sale From: 1goss@........... Date: Fri, 29 Jul 2005 07:17:21 +0000 I purchased this a few months ago and have not taken it out of the box Larry shipped it in. I did not need it I purchased 2 identical systems it was an extra setup I am not going to use now. 1 16-Bit A/D Board with WWV option and power supply = $245.00 1 2-Channel Amp/Filter Board = $110.00 1 Mounting Kit = $20.00 1 Garmin GPS 18 Receiver/Antenna sensor = $100.00 This was a total of = 475 I will take $350 I have a paypal account or I will take a check if it�s from someone on the list Thanks Bryan S Goss __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Safe impact source From: "Randy" rpratt@............. Date: Fri, 29 Jul 2005 18:21:35 -0500 Hi All, It occurred to me at the sporting goods store that powder pellets sold = for muzzle loading rifles could be used. Pyrodex and Triple-7 are 2 = brand names and there are others. They are packaged 50 to a package and = each equates to about 50 grains of black powder. They are not black = powder and so are much safer and cleaner to handle and use. They ignite = easily with a cap or shotgun primer and can be combined 1, 2, or 3 for = desired power. 3 pellets in a .50 caliber rifle generate over = 2000ft-lbs of energy. A 1/2" hole drilled about 3" deep in the end of a = heavy steel shaft could direct the energy down a post hole. Cost is $18 = to $22 for 50 depending on brand and pellet size. Check Cabelas.com for = info and ordering. =20 Randy

Hi All,

It occurred to me at the sporting goods = store=20 that powder pellets sold for muzzle loading rifles could be = used. =20 Pyrodex and Triple-7 are 2 brand names and there are others. They = are=20 packaged 50 to a package and each equates to about 50 grains of black=20 powder. They are not black powder and so are much safer and = cleaner to=20 handle and use. They ignite easily with a cap or shotgun primer = and can be=20 combined 1, 2, or 3 for desired power. 3 pellets in a .50 caliber = rifle=20 generate over 2000ft-lbs of energy. A 1/2" hole drilled about 3" = deep in=20 the end of a heavy steel shaft could direct the energy down a post = hole. =20 Cost is $18 to $22 for 50 depending on brand and pellet size. = Check=20 Cabelas.com for info and ordering.

Randy

Subject: Items Sold From: 1goss@........... Date: Sat, 30 Jul 2005 05:49:22 +0000 SOLD!- Thanks Bryan S Goss purchased this a few months ago and have not taken it out of the box Larry shipped it in. I did not need it I purchased 2 identical systems it was an extra setup I am not going to use now. 1 16-Bit A/D Board with WWV option and power supply = $245.00 1 2-Channel Amp/Filter Board = $110.00 1 Mounting Kit = $20.00 1 Garmin GPS 18 Receiver/Antenna sensor = $100.00 This was a total of = 475 I will take $350 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Thunder induced ground motion. From: "Timothy Carpenter" GeoDynamics@....... Date: Thu, 4 Aug 2005 14:50:45 -0400 All, =20 Have any of you developed a database of ground motion generated by thunderstorms? Much of my work involves structural and ground vibrations created by heavy machinery or blasting. Whenever I have a long-term monitoring setup I usually build-in a feature to shut the system down = during thunderstorms (I've had two systems fried by lightning). Accordingly, I = have very little data on the vibrations caused by lightning/thunder.=20 =20 I'm looking for a representative sampling of ground and structural = response, due to thunder, that can be compared to other sources =96 particularly blasting. In a quickie literature search, I find brief mention of = thunder, but never a reference to hard data. =20 Regards, =20 -Tim- =20 Timothy Carpenter, P.E., Pres., GeoDynamics Consultants, Inc. 5043 Whitlow Ct. Commerce Twp., Mi 48382 248-363-4529 (voice & fax) 248-766-1629 (cell) geodynamics@........... (primary) geodynamics@....... (secondary) =20 =20

All,

Have any of you developed a = database of ground motion generated by thunderstorms? Much of my work involves structural = and ground vibrations created by heavy machinery or blasting. Whenever I = have a long-term monitoring setup I usually build-in a feature to shut the = system down during thunderstorms (I've had two systems fried by lightning). = Accordingly, I have very little data on the vibrations caused by lightning/thunder. =

I'm looking for a representative = sampling of ground and structural response, due to thunder, that can be compared = to other sources – particularly blasting. In a quickie literature = search, I find brief mention of thunder, but never a reference to hard = data.

=A0

Regards,

-Tim-

Timothy = Carpenter, P.E., Pres.,
GeoDynamics Consultants, Inc.
5043 Whitlow = Ct.
Commerce Twp., Mi 48382
248-363-4529 (voice & fax)
248-766-1629 (cell)
geodynamics@........... = (primary)
geodynamics@....... = (secondary)

Subject: Homade Geophone From: "Geoff" gmvoeth@........... Date: Thu, 4 Aug 2005 16:46:35 -0700 Has Anyone ever made a horizontal Geophone using the pendulum idea with the magnet attached to as the weight of a pendulum and the coil fixed to the earth and free to move in all horizontal directions ? I would be interested in knowing what you used to dampen the mass and what overall gain you needed on the amplifier. The idea here is to get first time of arrival only and not worry about direction of ground motion. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: John Popelish jpopelish@........ Date: Thu, 04 Aug 2005 20:00:06 -0400 Geoff wrote: > Has Anyone ever made a horizontal Geophone > using the pendulum idea with the magnet > attached to as the weight of a pendulum > and the coil fixed to the earth and > free to move in all horizontal directions ? > I would be interested in knowing what you > used to dampen the mass and what overall > gain you needed on the amplifier. > The idea here is to get first time of arrival > only and not worry about direction of ground motion. I haven't gotten around to commissioning it yet, but I have built a geophone type structure horizontal seismometer. That is, the magnet structure produces radial field that passed through the entire solenoidal coil. I have the magnet structure mounted on the pendulum and the coil mounted to the base. This makes it a moving coil design, since, during a quake, the pendulum stands approximately still and the Earth and the base move. I made the magnet structure with a symmetrical pair of magnet sets, so there is no net external magnetic fields. This prevents changes of the Earth's magnetic field moving the pendulum. The coil moves relative to the magnets only in one axis. Damping is easy. A resistor across the coil can do that, or an additional conductive sheet (aluminum or copper) mounted near the outside of the magnet structure can produce damping drag. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: "Charles R. Patton" charles.r.patton@........ Date: Thu, 04 Aug 2005 17:06:36 -0700 This has two problems. 1) Geometrically the difficulty is to have an output for any direction movement. It would be easier to have two coils set for orthogonal output then do the vectorial addition in the PC (which would take two A/D channels also) . The PC could also give direction at the same time. It can be done with analog multipliers also if you're a bit of a masochist. 2) Having the magnet on the boom makes you very subject to variable magnetic fields all around, so then it becomes were you measuring a magnetic field variation or an earth movement. So I would suggest you set up your Foucault pendulum with two orthogonal coils standing up, and put the single magnet pole on the floor pointing directly into the bottom of the bob. Charles Patton Geoff wrote: > Has Anyone ever made a horizontal Geophone > using the pendulum idea with the magnet > attached to as the weight of a pendulum > and the coil fixed to the earth and > free to move in all horizontal directions ? > I would be interested in knowing what you > used to dampen the mass and what overall > gain you needed on the amplifier. > The idea here is to get first time of arrival > only and not worry about direction of ground motion. > > gmvoeth > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: ChrisAtUpw@....... Date: Thu, 4 Aug 2005 21:09:16 EDT In a message dated 05/08/2005, charles.r.patton@........ writes: This has two problems. 1) Geometrically the difficulty is to have an output for any direction movement. It would be easier to have two coils set for orthogonal output then do the vectorial addition in the PC (which would take two A/D channels also) . The PC could also give direction at the same time. It can be done with analog multipliers also if you're a bit of a masochist. However, it is fairly easy to make an orthogonal sensor using a square end mirror and four 8 sq mm photo diodes. I can get a noise level of about 15 nano metres. Maybe a square hole in an optical shutter with a light on one side and the photo diodes on the other? 2) Having the magnet on the boom makes you very subject to variable magnetic fields all around, so then it becomes were you measuring a magnetic field variation or an earth movement. Unless the field is enclosed, you will pick up a lot of AC power interference. Even with just a soft iron weight, you will pick up some unwanted magnetic noise. So I would suggest you set up your Foucault pendulum with two orthogonal coils standing up, and put the single magnet pole on the floor pointing directly into the bottom of the bob. Charles Patton ?? My magnets all come with two poles. You could use two rectangular coils and two sets of N+S NdFeB bar magnets pairs, at right angles on the end of the bob. Maybe with soft iron plates top and bottom and mild steel bolts to enclose the fields? I would prefer to put the coils on the end of a brass bob weight and sit the magnets and the soft iron plates comfortably on the ground. Chris Chapman

In a message dated 05/08/2005, charles.r.patton@........ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>This has=20 two problems.
1) Geometrically the difficulty is to have an output for=20= any=20 direction movement. It would be easier to have two coils set for orthogona= l=20 output then do the vectorial addition in the PC (which would take two A/D=20 channels also) . The PC could also give direction at the same time.=20
It can be done with analog multipliers also if you're a b= it=20 of a
masochist.

However, it is fairly easy to make an orthogona= l=20 sensor using a square end mirror and four 8 sq mm photo diodes. I=20= can=20 get a noise level of about 15 nano metres. Maybe a square hole in an optical= =20 shutter with a light on one side and the photo diodes on the other?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>2)=20 Having the magnet on the boom makes you very subject to variable
magne= tic=20 fields all around, so then it becomes were you measuring a
magnetic fi= eld=20 variation or an earth movement.

Unless the field is enclosed, you will pick up=20= a=20 lot of AC power interference. Even with just a soft iron weight, you wi= ll=20 pick up some unwanted magnetic noise.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>So I=20 would suggest you set up your Foucault pendulum with two orthogonal coils=20 standing up, and put the single magnet pole on the floor pointing directly= =20 into the bottom of the bob.
Charles Patton

?? My magnets all come with two poles. You coul= d=20 use two rectangular coils and two sets of N+S NdFeB bar magnets pairs, at ri= ght=20 angles on the end of the bob. Maybe with soft iron plates top and bottom and= =20 mild steel bolts to enclose the fields?

I would prefer to put the coils on the end of a= =20 brass bob weight and sit the magnets and the soft iron plates comfortab= ly=20 on the ground.

Chris Chapman

Subject: Re: Homade Geophone From: "Charles R. Patton" charles.r.patton@........ Date: Thu, 04 Aug 2005 20:14:49 -0700 Chris, I like the idea of optical shutters/slits. Back to Roger Baker's optical laser setups. Of course, when I mentioned single pole, I didn't mean a monopole, I just meant the N or S end of a bar magnet set so that the end is pointing up into the bob with the coils orthogonal. That's what comes of being too brief. As you point out, it is much more practical to mount the coils at some distance from each other on the bob and parallel to the ground, and then use a horseshoe magnet or multiple poles to excite both sides of the coil -- double your output, double your pleasure! The only down side, is you might want to balance the weight about the torsion rotation point so that linear gusts of air don't turn into torsion oscillations. If you really wanted to get trick, you could use a pair of coils per axis, and set them up for hum-bucking, while the magnets (two) are set up for aiding. Little or no shielding required as long as the noise source isn't too near (causes non-uniform field and poor cancellation.) Regards, Charles Patton ChrisAtUpw@....... wrote: >In a message dated 05/08/2005, charles.r.patton@........ writes: > >This has two problems. >1) Geometrically the difficulty is to have an output for any direction >movement. It would be easier to have two coils set for orthogonal output then do >the vectorial addition in the PC (which would take two A/D channels also) . >The PC could also give direction at the same time. >It can be done with analog multipliers also if you're a bit of a >masochist. > However, it is fairly easy to make an orthogonal sensor using a square >end mirror and four 8 sq mm photo diodes. I can get a noise level of about 15 >nano metres. Maybe a square hole in an optical shutter with a light on one >side and the photo diodes on the other? > >2) Having the magnet on the boom makes you very subject to variable >magnetic fields all around, so then it becomes were you measuring a >magnetic field variation or an earth movement. > Unless the field is enclosed, you will pick up a lot of AC power >interference. Even with just a soft iron weight, you will pick up some unwanted >magnetic noise. > >So I would suggest you set up your Foucault pendulum with two orthogonal >coils standing up, and put the single magnet pole on the floor pointing directly > into the bottom of the bob. >Charles Patton > ?? My magnets all come with two poles. You could use two rectangular >coils and two sets of N+S NdFeB bar magnets pairs, at right angles on the end of >the bob. Maybe with soft iron plates top and bottom and mild steel bolts to >enclose the fields? > > I would prefer to put the coils on the end of a brass bob weight and sit >the magnets and the soft iron plates comfortably on the ground. > > Chris Chapman > > > > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: james fisher kd6iwd@......... Date: Thu, 4 Aug 2005 20:32:11 -0700 (PDT) Hi everyone, thought I would describe my homemade "geophone". I noted that a voltmeter magnetic meter movement had a coil of wire suspended in a very high intensity magnetic field. the gap between the coil and the magnet is only 1 or 2 mm. The coil is free to rotate- indicating voltage by the attached meter pointer. If you move the pointer the coil also moves yelding a small current. I glued a right angle bracket on the meter needle using a THIN piece of aluminum cut out of a aluminum soda can with a ordinary pair of scissors. Remove rough edges with fine sandpaper. For my experiment I placed a small weight on the aluminum bracket. after amplifing the output I could detect footsteps. The bracket could be placed in contact with a pendulum arm and it might pick up the movement of the pendulum. This is a rather sensitive device because the high intensity alinco magnet is used with only a 1 or 2 mm air gap across the magnetic poles. best regards Jim __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: "Geoff" gmvoeth@........... Date: Fri, 5 Aug 2005 18:45:50 -0700 One thing you left out is the overall electrical gain you intend you use for your design Like I use a DC gain of about 100DB but if you are only looking at 1 Hz the realistic gain is about 89 to 90 DBV of gain. But I am using a commercially built vertical geophone at the moment and not the one that interests me. I am interested in the overall electrical gain you must give your amplifier/filter to show seismic noise on your recorder. I have found that to be the best level to use. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: "Geoff" gmvoeth@........... Date: Fri, 5 Aug 2005 20:07:06 -0700 The idea is to obtain a free period of one second or more 0.5 would be ideal are you able to control the free period of your 'meter movement Geophone' and if so how did you do it ? I have found you need a pendulum of 12 inch length and also a spring will behave according to the formula for a pendulum so like if you need a free period of one second for a spring then whatever mass will stretch the spring by 10 to 12 inches will give it a free period of one second or more. If you could build a spring with tension already built in you might then suspend a mass that will hang only 1 or more inches instead of 10 or 12. Getting the proper free period to do the job is the hardest part of making the Geophone especially if it is vertical. Without the proper free period the gain necessary to see those lower frequencies is too high and you run into all kinds of sensitivity problems with other electrical noises. Or so it seems to me. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: "Geoff" gmvoeth@........... Date: Fri, 5 Aug 2005 20:25:22 -0700 1. It seems to me that a cylindrical magnet inserted into the center a coil dangling freely might be the best way to go but it needs to be a very powerful magnet and have no more then 1mm of slop in any direction. The question is what dampening device to use is best I have found silicon oil of about 50WT should do nicely but trying to get your hands on silicon oil is like impossible in small quantities. 2. I have found most noise sources do not look anything like a seismic signal if the noise is infrequent you can filter out such things with your own human judgment. This is saying though that people are not out there intentionally trying to induce an EQ signal using noise into your particular system. 3. I am interested in knowing the cheapest way possible to build your own Geophone that consistently receives teleseismic signals over a long period of time The Geophone companies want like $3000 for a single vertical 1Hz Geophone...surely us amateurs can build a simple one for a Lab setting < opposed to a field setting > for much less like $20. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: John Popelish jpopelish@........ Date: Sat, 06 Aug 2005 00:15:40 -0400 Geoff wrote: > 1. It seems to me that a cylindrical magnet inserted into the center a coil > dangling freely might be the best way to go > but it needs to be a very powerful magnet and have no more > then 1mm of slop in any direction. The cylindrical magnets in geophones have a voice coil type winding around each end, , one wound each way, and connected in series. Then the coils are surrounded by an iron pipe that carries the flux passing radially out through one coil over to pass radially in through the other coil. The magnet and pipe are connected outside the ends of the coils. The coils are supported by spring structures at both ends. In a pendulum version, the pendulum structure replaces the support springs. > The question is what dampening > device to use is best > I have found silicon oil of about 50WT should do nicely > but trying to get your hands on silicon oil is like impossible > in small quantities. Such oil is used in copiers and laser printers as fuser oil. You can find that in many office supply places and on Ebay. > 2. I have found most noise sources do not look anything like a seismic > signal > if the noise is infrequent you can filter out such things > with your own human judgment. > This is saying though that people are not out there > intentionally trying to induce an EQ signal using noise > into your particular system. > > 3. I am interested in knowing the cheapest way possible to > build your own Geophone that consistently receives > teleseismic signals over a long period of time > The Geophone companies want like $3000 for a single > vertical 1Hz Geophone...surely us amateurs can build a simple one > for a Lab setting < opposed to a field setting > for > much less like $20. The magnets in my geophone type coil structure cost me about $50 on Ebay (4 of 1" diameter by 1/2 inch long and 16 of 1/2 inch diameter by 1/2 inch long neodymium iron boron), and the iron pole pieces that act as the the iron sleeve (but designed to contain most of the flux at the ends of the structure) cost me $100 to have machined. But the flux is fierce. I have to use screw jacks to assemble the magnet structure around the coils. This thing bits! __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: "Geoff" gmvoeth@........... Date: Fri, 5 Aug 2005 22:29:37 -0700 John Popelish Although the cost is kinda high I think we should all see what you have built for a sensor possibly you could publish a series of digital photos to show us the final product possibly the sequence of construction. If you can do this then give us a link to see what you have created. Some kind of reference for size would be nice to include. There are far to few people letting us know what they are doing. I think too many people are trying to capitalize on their ideas or possibly afraid of patent infingement but so long as we do not intend to profit from our ideas what worry should we have from the patent world. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: John or Jan Lahr JohnJan@........ Date: Fri, 05 Aug 2005 23:24:12 -0700 I've posted some pictures of a 1 Hz vertical seismometer that leaves a lot to be desired but is relatively quick and easy to build: http://jclahr.com/science/psn/wooden/ . If it does a reasonable job of recording earthquakes I'll post added details. Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Mathcad From: Mike Speed mike8s2@......... Date: Sat, 6 Aug 2005 12:17:33 -0700 (PDT) I have Mathcad 2001 and I would like to use it to display seismic data. I have a file consisting of raw numbers (one number per line). How do I read in the file and display it in Mathcad? Greg __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mathcad From: ian ian@........... Date: Sat, 06 Aug 2005 20:58:48 +0100 Hi, the function to read in the data is READPRN. You would have something like y:= READPRN("c:\mydata.dat") you might then do: i:=0..rows(y)-1 then plot y and i. You need to use the right key strokes to get the ":=" and "..", you don't get them by typing them. ":=" is entered by pressing ":" and ".." is entered by pressing ";". For the y axis, the y has to be entered with i as a subscript, this is achieved by typing "y[i". Bizarre but true... Try it! Also have a look at the examples. Hope that helps. Ian Mike Speed wrote: >I have Mathcad 2001 and I would like to use it to >display seismic data. I have a file consisting of raw >numbers (one number per line). How do I read in the >file and display it in Mathcad? > > >Greg > >__________________________________________________ >Do You Yahoo!? >Tired of spam? Yahoo! Mail has the best spam protection around >http://mail.yahoo.com >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: ChrisAtUpw@....... Date: Sat, 6 Aug 2005 18:46:03 EDT In a message dated 06/08/2005, JohnJan@........ writes: http://jclahr.com/science/psn/wooden/ Hi John, You may need to bend a bit of wire straight at both ends of the spring and clamp it. One of the problems with spring suspensions is noise from the loop ends. You could bore a small hole through the 'mass' bolt just under the head and clamp the wire between two washers? Put a similar clamp bolt on the frame? Noise can also be minimised by bending the wire to a V instead of a loop end and using a slightly sharper V of hard metal with a slightly rounded edge, like they do in weighing scales. You may get better results from the suspension if, instead of points, you use a couple of stainless steel ball bearings on the base column and either a square polished lathe tool or a glass microscope slide on the end of the arm. 1/4" bearings should do fine. If you just want to 'try it out' you should be able to buy several sizes of ordinary ball bearings from a cycle shop. You do need to place a drop of thin oil at the contact point to inhibit corrosion. I would be tempted to use a U magnet for the mass, like in the AS-1 and either a relay or a miniature transformer coil. Larry sells relay coils. To get good signals, you really need a high gradient magnetic field and lots of turns, preferably on a square section coil. Mouser sell a range of small transformers. You remove the I strips from both ends of the yoke, free up a central E strip on both sides with a knife blade and then push it out using blocks and a vice. You can then peel off and extract the remaining E strips to leave you with a nice square sensor coil on a plastic former. I use them for distance sensors with all the E strips replaced on one side, in the same way that Sean Morrissey did. If you use a single vertical magnet, you will likely pick up a lot of magnetic noise from the power wiring in your house, from fridges, central heating, electric cookers, from bikes, cars, lorries, trains and from the earth's field. You will still pick up noise with a U magnet, but it will be less. Both N & S poles face downward and you are not sensitive to side to side forces. A totally soft iron shielded Neo quad array would probably be too heavy. The best way is still to put the coil on the end of the arm with a brass weight and sit the magnet array out of harm's way on the floor! I notice that you mentioned damping magnets. Could you make an air damper with two different sizes of drinks cans, or one drinks can and an open topped tin set on the ground? The airflow resistance would come from the small circular but long air gap in between the cans? Maybe this is not too practical. It could be quite sensitive to air pressure variations. Just an off the cuff idea. You can get quite significant damping by drilling a round copper bar and sliding one pole of a cylindrical Neo magnet just inside it. I have tried every combination that I can think of for 'flat' magnetic damping systems. BY FAR THE MOST EFFECTIVE SYSTEM is to use rectangular Neo magnets mounted on two mild steel plates held apart by mild steel bolts. I use 3.5" x 2" x 1/4" bright mild steel plates and 1/4" mild steel bolts. On one inner face you place a N and a S Neo bar magnet pair, with the long sides together. Facing this on the other face is a S and a N Neo bar magnet pair. The poles are on the flat faces of the magnets. You suspend an Al or Cu damping blade in the central gap so that it moves at right angles to the long magnet join and overlaps the magnets by maybe 3/8". This avoids edge force effects between the blade and the magnets. The fields from the rear of the magnet pairs are closely linked by the soft iron, so that most of the mmf drives the fields in the central gap. This system gives a very sharp rate of change of field at the central join, allowing strong damping on a cental moving Cu / Al plate. Have fun! Regards, Chris Chapman

In a message dated 06/08/2005, JohnJan@........ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>http://jclahr.com/science/psn/wooden/

Hi John,

You may need to bend a bit of wire straight at=20= both=20 ends of the spring and clamp it. One of the problems with spring suspensions= is=20 noise from the loop ends. You could bore a small hole through the 'mass' bol= t=20 just under the head and clamp the wire between two washers? Put a similar cl= amp=20 bolt on the frame? Noise can also be minimised by bending the wire to a= V=20 instead of a loop end and using a slightly sharper V of hard metal= =20 with a slightly rounded edge, like they do in weighing scales.

You may get better results from the=20 suspension if, instead of points, you use a couple of stainless steel b= all=20 bearings on the base column and either a square polished lathe tool or a=20 glass microscope slide on the end of the arm. 1/4" beari= ngs=20 should do fine. If you just want to 'try it out' you should be able to buy=20 several sizes of ordinary ball bearings from a cycle shop. You do need=20= to=20 place a drop of thin oil at the contact point to inhibit corrosion.

I would be tempted to use a U magnet for the ma= ss,=20 like in the AS-1 and either a relay or a miniature transformer coi= l.=20 Larry sells relay coils. To get good signals, you really need a high gradien= t=20 magnetic field and lots of turns, preferably on a square section coil.

Mouser sell a range of small transformers. You=20 remove the I strips from both ends of the yoke, free up a central E str= ip=20 on both sides with a knife blade and then push it out using blocks= and=20 a vice. You can then peel off and extract the remaining E strips to lea= ve=20 you with a nice square sensor coil on a plastic former. I use them for dista= nce=20 sensors with all the E strips replaced on one side, in the same way tha= t=20 Sean Morrissey did.

If you use a single vertical magnet, you w= ill=20 likely pick up a lot of magnetic noise from the power wiring in your house,=20= from=20 fridges, central heating, electric cookers, from bikes, cars, lorries, train= s=20 and from the earth's field. You will still pick up noise with a U magnet, bu= t it=20 will be less. Both N & S poles face downward and you are not sensitive t= o=20 side to side forces. A totally soft iron shielded Neo quad array would proba= bly=20 be too heavy. The best way is still to put the coil on the end of the arm wi= th a=20 brass weight and sit the magnet array out of harm's way on the floor!

I notice that you mentioned damping magnets. Co= uld=20 you make an air damper with two different sizes of drinks cans, or one drink= s=20 can and an open topped tin set on the ground? The airflow=20 resistance would come from the small circular but long air gap in between th= e=20 cans? Maybe this is not too practical. It could be quite sensitive to air=20 pressure variations. Just an off the cuff idea.

You can get quite significant damping by=20 drilling a round copper bar and sliding one pole of a cylindrical Neo=20 magnet just inside it.

I have tried every combination that I can think= of=20 for 'flat' magnetic damping systems. BY FAR THE MOST EFFECTIVE SYSTEM is to=20= use=20 rectangular Neo magnets mounted on two mild steel plates held apart by=20= mild=20 steel bolts. I use 3.5" x 2" x 1/4" bright mild steel plates and 1/4" m= ild=20 steel bolts. On one inner face you place a N and a S Neo bar magne= t=20 pair, with the long sides together. Facing this on the other face is a S=20 and a N Neo bar magnet pair. The poles are on the flat faces of the=20 magnets. You suspend an Al or Cu damping blade in the central gap so th= at=20 it moves at right angles to the long magnet join and overlaps the=20 magnets by maybe 3/8". This avoids edge force effects between the=20 blade and the magnets. The fields from the rear of the magnet pairs are clos= ely=20 linked by the soft iron, so that most of the mmf drives the fields in t= he=20 central gap. This system gives a very sharp rate of change of field at=20= the=20 central join, allowing strong damping on a cental moving Cu /=20 Al plate.

Have fun!

Regards,

Chris Chapman

Subject: Re: Homade Geophone From: Stephen & Kathy skmort@.......... Date: Sat, 06 Aug 2005 16:03:50 -0700 Question,,, I understand that the 1 sec AS-1 vertical uses an amp-filter which compensates for the signal rolloff so that it works out to about 25 or 30 sec.,,,, is the schematic for it, or a similar amp-filter available anywhere???? I'd like to adapt it to use with my 4.5 sec vertical!! I can do it after the fact, using Bob McClures excellent software, but would like to fix the signal before the A/D converter, to save a few steps!! Interesting that they give details on building the AS-1 sensor, but not the electronic,, that I can find?? Thanks in advance, Stephen Mortensen PSN Station #55 near Pilot Hill Ca. USA 38.828N 120.979W John or Jan Lahr wrote: > I've posted some pictures of a 1 Hz vertical seismometer that leaves a > lot to be desired but is relatively quick and easy to build: > http://jclahr.com/science/psn/wooden/ . If it does a reasonable job of > recording earthquakes I'll post added details. > > Cheers, > John > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: John or Jan Lahr JohnJan@........ Date: Sat, 06 Aug 2005 17:16:08 -0700 Hi Chris, Thanks for the feedback. At 03:46 PM 8/6/2005, you wrote: >In a message dated 06/08/2005, JohnJan@........ writes: >http://jclahr.com/science/psn/wooden/ > >Hi John, > > You may need to bend a bit of wire straight at both ends of the > spring and clamp it. One of the problems with spring suspensions is > noise from the loop ends. You could bore a small hole through the > 'mass' bolt just under the head and clamp the wire between two > washers? Put a similar clamp bolt on the frame? Noise can also be > minimised by bending the wire to a V instead of a loop end and > using a slightly sharper V of hard metal with a slightly rounded > edge, like they do in weighing scales. Good suggestions. > You may get better results from the suspension if, instead of > points, you use a couple of stainless steel ball bearings on the > base column and either a square polished lathe tool or a glass > microscope slide on the end of the arm. 1/4" bearings should do > fine. If you just want to 'try it out' you should be able to buy > several sizes of ordinary ball bearings from a cycle shop. You do > need to place a drop of thin oil at the contact point to inhibit corrosion. I tired ball bearings but the boom is so heavy that they tended to slip off of the support I guess the way to compensate would be to tilt the glass slide so that it would tend to support the weight of the boom. I think that the friction is too high with the pointed drill bits, so I'll next try the pivot pictured here: http://jclahr.com/science/psn/wooden/target11.html I think the ball bearings would be easier for a teacher to set up, so that might be the final solution. > I would be tempted to use a U magnet for the mass, like in the > AS-1 and either a relay or a miniature transformer coil. Larry > sells relay coils. To get good signals, you really need a high > gradient magnetic field and lots of turns, preferably on a square section coil. > Mouser sell a range of small transformers. You remove the I > strips from both ends of the yoke, free up a central E strip on > both sides with a knife blade and then push it out using blocks and > a vice. You can then peel off and extract the remaining E strips to > leave you with a nice square sensor coil on a plastic former. I use > them for distance sensors with all the E strips replaced on one > side, in the same way that Sean Morrissey did. > If you use a single vertical magnet, you will likely pick up a > lot of magnetic noise from the power wiring in your house, from > fridges, central heating, electric cookers, from bikes, cars, > lorries, trains and from the earth's field. You will still pick up > noise with a U magnet, but it will be less. Both N & S poles face > downward and you are not sensitive to side to side forces. A > totally soft iron shielded Neo quad array would probably be too > heavy. The best way is still to put the coil on the end of the arm > with a brass weight and sit the magnet array out of harm's way on the floor! I know I'm asking for problems with the current setup, but it does have the advantage of being quick to assemble! As long as some surface waves show up occassionally, I'll be satisfied. I guess the best approach would be to have a series of possible designs, from the most crude to the most advanced. Then the student, educator or amateur could select which one to start with and if some success is obtained, would be encouraged to build another of higher difficulty and/or greater expense. > I notice that you mentioned damping magnets. Could you make an > air damper with two different sizes of drinks cans, or one drinks > can and an open topped tin set on the ground? The airflow > resistance would come from the small circular but long air gap in > between the cans? Maybe this is not too practical. It could be > quite sensitive to air pressure variations. Just an off the cuff idea. In my current model I'm not damping at all. I think the wide boom is acting like an air damper, or the friction at the "point hinge" is damping quite a bit. I like the drink-can damper idea -- much better than messy oil and less expensive than magnets. Just as long as it isn't too hard to get things aligned so there is no scraping between the cans. The outer container could be a glass so that one could see if there is contact at any point.Maybe the gap could be slightly larger but the damping still effective with water. One would have to top off the water from time to time! > You can get quite significant damping by drilling a round > copper bar and sliding one pole of a cylindrical Neo magnet just inside it. > I have tried every combination that I can think of for 'flat' > magnetic damping systems. BY FAR THE MOST EFFECTIVE SYSTEM is to > use rectangular Neo magnets mounted on two mild steel plates held > apart by mild steel bolts. I use 3.5" x 2" x 1/4" bright mild steel > plates and 1/4" mild steel bolts. On one inner face you place a N > and a S Neo bar magnet pair, with the long sides together. Facing > this on the other face is a S and a N Neo bar magnet pair. The > poles are on the flat faces of the magnets. You suspend an Al or Cu > damping blade in the central gap so that it moves at right angles > to the long magnet join and overlaps the magnets by maybe 3/8". > This avoids edge force effects between the blade and the magnets. > The fields from the rear of the magnet pairs are closely linked by > the soft iron, so that most of the mmf drives the fields in the > central gap. This system gives a very sharp rate of change of field > at the central join, allowing strong damping on a cental moving Cu / Al plate. The damping from the magnets taped to the side of the boom worked OK and might be OK (as pictured here: http://jclahr.com/science/psn/wooden/target5.html ) for the most crude setup, if some kind of air damping doesn't do it. A more advanced version with moving coil might then use the system you describe above. > Have fun! > > Regards, > > Chris Chapman I'll be visiting my kids in California for the next 10 days, so progress will be delayed! I am having fun. Actually the zero level (or minus one?) sensor is shown in this and the next few pictures from the day camp I helped out with this summer: http://jclahr.com/science/earth_science/ptmsc/pt2005/target24.html The kids wound their own coils and arranged the suspension for a magnet. In the process they learned that magnet wire has a coating that must be removed at the attachment points, that a moving magnet creates a small voltage, that a seismogram displays the time history of the movement of the magnet within the coil, and that fast motion generated a larger signal than slow motion (velocity sensor). Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Review of Chapmna book From: BOB BARNS royb1@........... Date: Sat, 06 Aug 2005 20:19:58 -0400 Hi gang, There is a laudatory review of Chris Chapman's book in Physics Today (physicstoday.com) Fundamentals of Seismic Wave Propagation - Physics Today August 2005 Fundamentals of Seismic Wave Propagation by Chris Chapman covers the mathematical development of asymptotic ray theory for seismic waves. Chapman's book is most suitable for a graduate theoretical course in high-frequency seismology and could be compared with Quantitative Seismology: Theory and Methods (W. H. Freeman, 1980) by Keiiti Aki and Paul Richards. Chapman's text may serve a similar role for high-frequency seismology as Theoretical Global Seismology (Princeton U. Press, 1998) by ... Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: John or Jan Lahr JohnJan@........ Date: Sat, 06 Aug 2005 17:24:10 -0700 The design of the AS1 "black box" is not published, but you can design an amplifier that will work in a similar way by setting the peak gain at 20 seconds period. I think Chris Chapman has the most experience with amplifier/filter design, so he might be able to suggest a circuit for you. You will be fighting electronic noise to get out to 20 seconds and even the AS1 will see 20 second surface waves only for the very largest events. Usually the surface wave recorded on an AS1 are in the 12 to 16 second range (very rough estimate!). Cheers, John At 04:03 PM 8/6/2005, you wrote: >Question,,, I understand that the 1 sec AS-1 vertical uses an >amp-filter which compensates for the signal rolloff so that it works >out to about 25 or 30 sec.,,,, is the schematic for it, or a >similar amp-filter available anywhere???? I'd like to adapt it to >use with my 4.5 sec vertical!! I can do it after the fact, using >Bob McClures excellent software, but would like to fix the signal >before the A/D converter, to save a few steps!! Interesting that >they give details on building the AS-1 sensor, but not the >electronic,, that I can find?? > Thanks in advance, > Stephen Mortensen > PSN Station #55 > near Pilot Hill Ca. USA > 38.828N 120.979W > >John or Jan Lahr wrote: > >>I've posted some pictures of a 1 Hz vertical seismometer that >>leaves a lot to be desired but is relatively quick and easy to >>build: http://jclahr.com/science/psn/wooden/ . If it does a >>reasonable job of recording earthquakes I'll post added details. >>Cheers, >>John >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body >of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: ChrisAtUpw@....... Date: Sat, 6 Aug 2005 21:15:33 EDT In a message dated 07/08/2005, skmort@.......... writes: Question,,, I understand that the 1 sec AS-1 vertical uses an amp-filter=20 which compensates for the signal rolloff so that it works out to about 25 o= r=20 30 sec.,,,, is the schematic for it, or a similar amp-filter available=20 anywhere? Hi Stephen,=20 =20 Have a look at _http://jclahr.com/science/psn/as1/as1_resp/index.html_=20 (http://jclahr.com/science/psn/as1/as1_resp/index.html) and in particular=20= Fig=20 2 for the AS-1 characteristics. Is this adequate for your purposes? I don't= =20 know of a published circuit. I can't answer your question directly since the answer depends on your=20 sensor type. Distance measuring sensors may be easier to compensate than=20 velocity sensors. =20 For extending velocity type sensors look at Roberts, P. M. (1989). =E2= =80=9CA=20 Versatile Equalization Circuit for Increasing Seismometer Velocity Response= =20 Below the Natural Frequency=E2=80=9C, Bull. Seism. Soc. Am., 79, 1607-1617=20= This is in=20 effect a particular type of bass boost amplifier, which keeps the phase cha= nges=20 in check to give a fairly flat output through fc. The circuit has high gain= =20 at very low frequencies, which may or may not give you noise problems. One=20 'fix' is to fit an extra 3 pole high pass filter at your low frequency limi= t. =20 The other way to do it is to set up a narrow band pass amplifier with a= =20 particular low frequency limit of maximum gain, which then has a gain at=20 higher frequencies inversely proportional to the frequency. You need differ= ent=20 filter laws for distance and for velocity measuring transducers. You could=20= also=20 tailor the gain to be constant above the natural resonant frequency. =20 Allan Coleman wrote an article on lengthening the period of a Lehman se= e=20 _http://psn.quake.net/lpveloc.html_ (http://psn.quake.net/lpveloc.html)=20 =20 On second thoughts, the Shackleford-Gundersen circuit does just this.=20 See _http://psn.quake.net/sgboard.html_ (http://psn.quake.net/sgboard.html)=20= and=20 linked documentation. But it has a distance sensor, so it only requires one= =20 integration step. I'd like to adapt it to use with my 4.5 sec vertical!! I can do it after=20= =20 the fact, using Bob McClures excellent software, but would like to fix the =20 signal before the A/D=20 converter, to save a few steps! Interesting that they give details on=20 building the AS-1 sensor, but not the electronics, that I can find? Thanks in advance, Stephen Mortensen Regards, =20 Chris Chapman

In a message dated 07/08/2005, skmort@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Question,,, I understand that the 1 sec AS-1 vertical= uses=20 an amp-filter which compensates for the signal rolloff so that it works ou= t to=20 about 25 or 30 sec.,,,, is the schematic for it, or a similar=20 amp-filter available anywhere?

Hi Stephen,

Have a look at http://jclahr= ..com/science/psn/as1/as1_resp/index.html and=20 in particular Fig 2 for the AS-1 characteristics. Is this adequate for your=20 purposes? I don't know of a published circuit.

I can't answer your question directly since the= =20 answer depends on your sensor type. Distance measuring sensors may be=20 easier to compensate than velocity sensors.

For extending velocity type sensors look at=20 Roberts, P. M. (1989). =E2=80=9CA Versatile Equalization Circuit for Increas= ing=20 Seismometer Velocity Response Below the Natural Frequency=E2=80=9C, Bull. Se= ism. Soc.=20 Am., 79, 1607-1617 This is in effect a particular type of bass boost amplifi= er,=20 which keeps the phase changes in check to give a fairly flat output through=20= fc.=20 The circuit has high gain at very low frequencies, which may or may not give= you=20 noise problems. One 'fix' is to fit an extra 3 pole high pass filter at= =20 your low frequency limit.

The other way to do it is to set up a narrow ba= nd=20 pass amplifier with a particular low frequency limit of maximum gain, which=20= then=20 has a gain at higher frequencies inversely proportional to the frequenc= y.=20 You need different filter laws for distance and for velocity measuring=20 transducers. You could also tailor the gain to be constant above the=20 natural resonant frequency.

Allan Coleman wrote an article on lengthening t= he=20 period of a Lehman see http://psn.quake.net/lpveloc.html=

On second thoughts, the Shackleford-Gundersen=20 circuit does just this. See http://psn.quake.net/sgboard.html= and=20 linked documentation. But it has a distance sensor, so it only requires one=20 integration step.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I'd like=20 to adapt it to use with my 4.5 sec vertical!!   I can do it afte= r=20 the fact, using Bob McClures excellent software, but would like to fix the= =20 signal before the A/D
converter, to save a few=20 steps! Interesting that they give details on building the AS-1 sensor= ,=20 but not the electronics, that I can find?
   Thanks in=20 advance,
   Stephen Mortensen

Regards,

Chris Chapman

Subject: Re: Review of Chapmna book From: Angel sismos@.............. Date: Sat, 6 Aug 2005 21:07:09 -0500 Congratulation Chris! Way to go! Here is the URL for Chris' book. http://www.cambridge.org/catalogue/catalogue.asp?isbn=052181538X Angel Saturday, August 6, 2005, 7:19:58 PM, you wrote: > Hi gang, > There is a laudatory review of Chris Chapman's book in Physics Today > (physicstoday.com) > Fundamentals of Seismic Wave Propagation - Physics Today August 2005 > Fundamentals of Seismic Wave Propagation by Chris Chapman covers the > mathematical development of asymptotic ray theory for seismic waves. > Chapman's book is most suitable for a graduate theoretical course in > high-frequency seismology and could be compared with Quantitative > Seismology: Theory and Methods (W. H. Freeman, 1980) by Keiiti Aki and > Paul Richards. Chapman's text may serve a similar role for > high-frequency seismology as Theoretical Global Seismology (Princeton U. > Press, 1998) by ... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Thunder induced ground motion. From: "Geoff" gmvoeth@........... Date: Sun, 7 Aug 2005 12:43:10 -0700 I have been watching grams for quite a few years now through various thunderstorms and found practically no effects below 2 Hz which is the only place I look I recommend you concentrate your efforts at frequencies over 10Hz and possibly 20Hz if you are interested in the effects of thunder. If you get a trace from a helicopter flying over you are probably good for thunder also. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Mathcad From: Mike Speed mike8s2@......... Date: Mon, 8 Aug 2005 05:32:45 -0700 (PDT) When I try to plot a *large* datafile on Mathcad, it gives me an error: Can't plot this many points. How do I fix this? Also, how do I do a heliplot in Mathcad? Thanks, Greg ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Mathcad From: ian ian@........... Date: Mon, 08 Aug 2005 16:44:04 +0100 Hi, I had a play, the maximum # points is 500,000. If you are sampling @ 50 sps, then this is approximately 15 hours. For longer you could sub-sample. If you averaged every 2 points into one then that would allow you to plot a day's worth. Have a look at the examples on polar plots. That may be the way to do heliplots... Ian Mike Speed wrote: >When I try to plot a *large* datafile on Mathcad, it >gives me an error: > >Can't plot this many points. > >How do I fix this? > >Also, how do I do a heliplot in Mathcad? > >Thanks, > >Greg > > > >____________________________________________________ >Start your day with Yahoo! - make it your home page >http://www.yahoo.com/r/hs > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: ChrisAtUpw@....... Date: Mon, 8 Aug 2005 22:30:11 EDT In a message dated 06/08/2000, gmvoeth@........... writes: I am interested in knowing the cheapest way possible to build your own Geophone that consistently receives teleseismic signals over a long period of time Hi there, The cheapest seismic sensor that I know of is a piezo sounder disk with a weight attached to the centre. Look for a 41 - 50 mm disk with a natural capacity from 40 to 100 nF. I get a sensitivity out to over 4 sec this way and it gives rather more output than a traditional geophone. The disk I use costs about $1. I stick a screw head to the centre of the disk with modified acrylic twinpack glue (not epoxy), mount it in a tube, screw on a 1.5" cylindrical weight ~50 gm and mount a V suspension at the free end of the weight. You can also use 1/2" shim strip. This gives a predominantly single axis sensitivity, you can use it either vertically or horizontally and it acts as a sensitive accelerometer. My loaded disk has a natural resonance at ~170 Hz, so damping is not a real problem, so long as I use a low pass filter. However, you can damp it with sorbothane, polyurethane foam, or magnetically. I use a low noise CMOS opamp with a synthetic impedance of ~100 M Ohms immediately followed by a high pass filter set to 7 sec. You do have to provide fairly good thermal isolation, as the disk behaves like a very tiny battery as the temperature of the PZT drifts. You need to mount it in a dry container, preferably with some silica gell and have / provide electrostatic screening. You need two signal diodes connected opposite ways across the disk to protect the input of the opamp. The disks on their own can generate many 10s of volts if knocked ~ instant death to an opamp. Remember that the ordinary glass silicon signal diodes are usually quite photo sensitive. It took me about 1 hr to find out where all the power hum was coming from - optically from the striplight in the kitchen! If you just want really low cost sensors for P & S waves, ~4 sec to 10 Hz, this is about the bottom line..... Regards, Chris Chapman

In a message dated 06/08/2000, gmvoeth@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2> I=20 am interested in knowing the cheapest way possible to build your own=20 Geophone that consistently receives teleseismic signals over a long=20 period of time

Hi there,

The cheapest seismic sensor that I know of= =20 is a piezo sounder disk with a weight attached to the centre. Look for=20= a 41=20 - 50 mm disk with a natural capacity from 40 to 100 nF. I get a sensitivity=20= out=20 to over 4 sec this way and it gives rather more output than a traditional=20 geophone. The disk I use costs about $1. I stick a screw head to the ce= ntre=20 of the disk with modified acrylic twinpack glue (not epoxy), mount it in a t= ube,=20 screw on a 1.5" cylindrical weight ~50 gm and mount a V suspension at the fr= ee=20 end of the weight. You can also use 1/2" shim strip.

This gives a predominantly single axis sensitiv= ity,=20 you can use it either vertically or horizontally and it acts as a sensitive=20 accelerometer. My loaded disk has a natural resonance at ~170 Hz, so damping= is=20 not a real problem, so long as I use a low pass filter. However, you can dam= p it=20 with sorbothane, polyurethane foam, or magnetically.

I use a low noise CMOS opamp with a synthetic=20 impedance of ~100 M Ohms immediately followed by a high pass filter set=20 to 7 sec. You do have to provide fairly good thermal isolation, as= the=20 disk behaves like a very tiny battery as the temperature of the PZT=20 drifts. You need to mount it in a dry container, preferably with some=20 silica gell and have / provide electrostatic screening.

You need two signal diodes connected oppos= ite=20 ways across the disk to protect the input of the opamp. The disks on their o= wn=20 can generate many 10s of volts if knocked ~ instant death to an opamp. Remem= ber=20 that the ordinary glass silicon signal diodes are usually quite photo sensit= ive.=20 It took me about 1 hr to find out where all the power hum was coming from -=20 optically from the striplight in the kitchen!

If you just want really low cost sensors for P=20 & S waves, ~4 sec to 10 Hz, this is about the bottom line.....

Regards,

Chris Chapman

Subject: Re: Homade Geophone From: "Geoff" gmvoeth@........... Date: Mon, 8 Aug 2005 19:42:58 -0700 ChrisAtUpw The Piezo Idea is very interesting Have you ever heard of a strain guage approach where you just hang a 10# or so weight from a strainguage and measure the tiny weight changes due to ground acceleration ?? It sounds a lot like the piezo idea but a strain guage would be resistive in nature I believe. At the moment I am using the top 9 bits of a 12 bit A/D converter looking at a +/- 2.048 voltage swing through amplifier filter with a gain of about 90DB will that same setup work with the piezo element ? Do I need a special preamp for the piezo element ? gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Homade Geophone From: ChrisAtUpw@....... Date: Tue, 9 Aug 2005 11:59:00 EDT In a message dated 09/08/2005, gmvoeth@........... writes: The Piezo Idea is very interesting Have you ever heard of a strain guage approach where you just hang a 10# or so weight from a strainguage and measure the tiny weight changes due to ground acceleration ?? Hi there, The strain gauge a) will not be anything like sensitive enough b) it is quite fragile and won't take overloads c) as primarily a resistive device, it has a fairly high power dissipation d) they are not exactly cheap. It sounds a lot like the piezo idea but a strain guage would be resistive in nature I believe. The maximum output is less that 1% of the input voltage. At the moment I am using the top 9 bits of a 12 bit A/D converter looking at a +/- 2.048 voltage swing through amplifier filter with a gain of about 90DB will that same setup work with the piezoelement ? I don't know your instrument setup and your description does not make it clear. I would not expect you to need 90 dB gain. Do I need a special preamp for the piezo element ? Does your amplifier have a low noise CMOS input opamp with a controlled DC impedance of 100 M Ohms? Are you just starting seismology and electronics? Regards, Chris Chapman

In a message dated 09/08/2005, gmvoeth@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 Piezo Idea is very interesting

Have you ever heard of a strain guag= e=20 approach where you just hang a 10# or so weight from a strainguage and mea= sure=20 the tiny weight changes due to ground acceleration ??

Hi there,

The strain gauge a) will not be anything like=20 sensitive enough b) it is quite fragile and won't take overloads c) as prima= rily=20 a resistive device, it has a fairly high power dissipation d) they are=20= not=20 exactly cheap.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>It=20 sounds a lot like the piezo idea but a strain guage would be resistive in=20 nature I believe.

The maximum output is less that 1% of the=20 input voltage.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>At the=20 moment I am using the top 9 bits of a 12 bit A/D converter looking at a +/= -=20 2.048 voltage swing through amplifier filter with a gain of about 90DB wil= l=20 that same setup work with the piezoelement ?

I don't know your instrument setup and your=20 description does not make it clear. I would not expect you to need 90 dB=20 gain.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Do I=20 need a special preamp for the piezo element ?

Does your amplifier have a low noise CMOS input= =20 opamp with a controlled DC impedance of 100 M Ohms?

Are you just starting seismology and electronic= s?=20

Regards,

Chris Chapman

Subject: RE: Homade Geophone From: "Steve Hammond" shammon1@............. Date: Tue, 9 Aug 2005 09:24:21 -0700 In 1991 one of the PSN members build a number of piezo devices. He had some issues with the output because if you "tap" it hard, the output can be quite high and damage the electronics. The devices were built from the old Apple butterfly fans. The original fan units contained two piezo devices and had two flippers that osculated when power was applied. The seismic design went something like this. Cut the fan in half. You now have two piezo devices to work with. Take a three inch length of 1-inch PVC pipe and cap one end. Put a small hole in the cap, run the wires through the hole, epoxy the piezo end in the cap with the flipper remaining free. Next, epoxy a small fishing weight on the end of the flipper. Once the epoxy is set, drill another small hole in the second cap and PVC glue it to the pipe. Last, fill the pipe with #30 motor oil and cap the filler hole with epoxy. The devices worked best for very high freq and did not work at all for low freq. Because the flippers are ridged, the devices were extremely directional. Regards, Steve Hammond PSN San Jose, Aptos CA -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Tuesday, August 09, 2005 8:59 AM To: psn-l@.............. Subject: Re: Homade Geophone In a message dated 09/08/2005, gmvoeth@........... writes: The Piezo Idea is very interesting Have you ever heard of a strain guage approach where you just hang a 10# or so weight from a strainguage and measure the tiny weight changes due to ground acceleration ?? Hi there, The strain gauge a) will not be anything like sensitive enough b) it is quite fragile and won't take overloads c) as primarily a resistive device, it has a fairly high power dissipation d) they are not exactly cheap. It sounds a lot like the piezo idea but a strain guage would be resistive in nature I believe. The maximum output is less that 1% of the input voltage. At the moment I am using the top 9 bits of a 12 bit A/D converter looking at a +/- 2.048 voltage swing through amplifier filter with a gain of about 90DB will that same setup work with the piezoelement ? I don't know your instrument setup and your description does not make it clear. I would not expect you to need 90 dB gain. Do I need a special preamp for the piezo element ? Does your amplifier have a low noise CMOS input opamp with a controlled DC impedance of 100 M Ohms? Are you just starting seismology and electronics? Regards, Chris Chapman

In 1991 one of the PSN members = build a=20 number of piezo devices. He had some issues with the output = because if=20 you "tap" it hard, the output can be quite high and damage the = electronics. The devices were = built from=20 the old Apple butterfly fans. The original fan units contained two piezo = devices=20 and had two flippers that osculated when power was applied.=20

The seismic design went something = like this.=20 Cut the fan in half. You now have two piezo devices to work with. Take a = three=20 inch length of 1-inch PVC pipe and cap one end. Put a small hole in the = cap, run=20 the wires through the hole, epoxy the piezo end in the cap with the = flipper=20 remaining free. Next, epoxy a small fishing weight on the end of the = flipper.=20 Once the epoxy is set, drill another small hole in the second cap and = PVC glue=20 it to the pipe. Last, fill the pipe with #30 motor oil and cap the = filler hole=20 with epoxy. The devices worked = best for=20 very high freq and did not work at all for low freq. Because the = flippers are=20 ridged, the devices were extremely directional.

Regards, Steve = Hammond

PSN San Jose, Aptos = CA

-----Original Message-----
From:=20 psn-l-request@.............. = [mailto:psn-l-request@...............On Behalf=20 Of ChrisAtUpw@.......
Sent: Tuesday, August 09, 2005 = 8:59=20 AM
To: psn-l@..............
Subject: Re: Homade=20 Geophone

In a message dated 09/08/2005, gmvoeth@........... writes:
The Piezo Idea = is very=20 interesting

Have you ever heard of a strain guage approach = where you=20 just hang a 10# or so weight from a strainguage and measure the tiny = weight=20 changes due to ground acceleration ??

Hi there,

The strain gauge a) will not be anything = like=20 sensitive enough b) it is quite fragile and won't take overloads c) as = primarily a resistive device, it has a fairly high power = dissipation d)=20 they are not exactly cheap.

It sounds a lot = like the=20 piezo idea but a strain guage would be resistive in nature I=20 believe.

The maximum output is less that 1% = of the=20 input voltage.

At the moment I = am using=20 the top 9 bits of a 12 bit A/D converter looking at a +/- 2.048 = voltage=20 swing through amplifier filter with a gain of about 90DB will that = same=20 setup work with the piezoelement ?

I don't know your instrument setup and = your=20 description does not make it clear. I would not expect you to need 90 = dB=20 gain.

Do I need a = special preamp=20 for the piezo element ?

Does your amplifier have a low noise CMOS = input=20 opamp with a controlled DC impedance of 100 M Ohms?

Are you just starting seismology and = electronics?=20

Regards,

Chris Chapman

Subject: Re: Homade Geophone From: ChrisAtUpw@....... Date: Tue, 9 Aug 2005 18:19:22 EDT In a message dated 09/08/2005, shammon1@............. writes: In 1991 one of the PSN members build a number of piezo devices. He had some issues with the output because if you "tap" it hard, the output can be quite high and damage the electronics. Hi There, For anyone who wants to try out a loaded piezo disk, the Digi-Key 102-1170-ND at $1.62 looks suitable. It is 44mm OD, has a nominal capacity of 70 nF and wire leads. It's natural frequency is 600 Hz. Mouser also stock a similar item 665 KBI 4406. I use Holdtite Acrylic Adhesive ST3295 in a twin syringe pack. This adhesive stays a bit flexible and the set time is about 5 min. It does NOT go brittle like epoxies. I glue a screw head to the centre of the brass disk and then screw a weight onto that. You crack fewer disks that way.... You can also use twinpack polyurethane adhesive. If you try to solder a screw head onto the disk, the heat depolarises the PZT element. It is also likely to crack it. I use weights of about 1 to 3 oz -- 30 to 100 gm, typically ~50 gm. My disks are a bit stiffer than the above ones, so 1 to 1.5 oz should be OK. You DO need to connect two signal diodes across the piezo element to protect the input to the opamp - see above. The devices worked best for very high freq and did not work at all for low freq. My disk works out to it's 4 Sec limit OK. You depend on the CR time constant to enable you to see the longer periods, but the output decreases, as you would predict for an accelerometer. 70 nF across 47 M Ohms = 3.3 seconds. Regards, Chris Chapman

In a message dated 09/08/2005, shammon1@............. writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>In 1991 one of the PSN members build a number o= f=20 piezo devices. He had some issues with the output because if you= =20 "tap" it hard, the output can be quite high and damage the=20 electronics.

Hi There,

For anyone who wants to try out a loaded piezo=20 disk, the Digi-Key 102-1170-ND at $1.62 looks suitable. It is 44mm OD, has a= =20 nominal capacity of 70 nF and wire leads. It's natural frequency is 600= Hz.=20 Mouser also stock a similar item 665 KBI 4406.

I use Holdtite Acrylic Adhesive ST3295 in a twi= n=20 syringe pack. This adhesive stays a bit flexible and the set time is about 5= =20 min. It does NOT go brittle like epoxies. I glue a screw head to the centre=20= of=20 the brass disk and then screw a weight onto that. You crack fewer disks that= =20 way.... You can also use twinpack polyurethane adhesive.

If you try to solder a screw head onto the disk= ,=20 the heat depolarises the PZT element. It is also likely to crack it. I use=20 weights of about 1 to 3 oz -- 30 to 100 gm, typically ~50 gm. My disks are a= bit=20 stiffer than the above ones, so 1 to 1.5 oz should be OK.

You DO need to connect two signal diodes across= the=20 piezo element to protect the input to the opamp - see above.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The devices worked best for very high freq and=20= did=20 not work at all for low freq.

My disk works out to it's 4 Sec limit OK. You=20 depend on the CR time constant to enable you to see the longer periods, but=20= the=20 output decreases, as you would predict for an accelerometer. 70 nF acro= ss=20 47 M Ohms =3D 3.3 seconds.

Regards,

Chris Chapman

Subject: Re: Homade Geophone From: "Geoff" gmvoeth@........... Date: Tue, 9 Aug 2005 19:03:49 -0700 Chris Chapman > The strain gauge a) will not be anything like sensitive enough b) it is > quite fragile and won't take overloads c) as primarily a resistive device, it > has a fairly high power dissipation d) they are not exactly cheap. I have seen delicate scales before where the mass under test hoovers and often I thought that would make a wonderful EQ sensor like the globe which is suspended in thin air by magnetic/optic feedback loop the mass is held stationary and you would measure the electrical signal used to keep the mass hoovering. You might reduce the power reqired by such a thing through the use of springs and levers using the magnetic forces only for the final gram or two of weight. I have never seen such an eq detector before. > Do I need a special preamp for the piezo element ? > Does your amplifier have a low noise CMOS input opamp with a controlled > DC impedance of 100 M Ohms? > > Are you just starting seismology and electronics? I am using op177G opamps and like them very much but they are not CMOS. I like to use the preamp and postamp as a differential amplifier using the smallest resistors possible to do the job. The filter is between the two so no amps will be jammable before the desired signals reach their destination. I think if you used two of your weighted crystals centered about ground and properly phased the diff amp might work just fine. I have no formal training in op amps or advanced electronics I have picked up most of what I know through unguided research. Remember those old car radios that used iron slugs to tune the radio I would think such a scheme might also make for a great FM type motion detector but because of the possibility of RFI being generated by the RF circuits I will not try such a thing. I have been playing around with seismic stuff for about 10 years now experimenting from time to time with a breadboard but this has been intermittent at best because other things always seem to interfere with my efforts. It is a way I like to spend my time and money so that is why I mess around with it. My current geophone sits on the same slab as the mobile home I live in with awnings coupling wind noise to the slab also as well as footsteps from anyone in the area. Vehicular noise is common as well as heavy construction and the bedrock maybe 800 feet deep covered by valley fill. It is not a good location for a receiver but still I am able to receive teleseismic signals when things are quiet. I would put the geophone underground but I must contend with a septic tank and high voltage power lines about 60 feet away so the underground option is not possible so it seems. I had a special slab put in just for a seismometer but my mobile home was changed so the heat pump now sets within 10 feet of the slab making unacceptable noise that will swamp/jam the preamp when the machine turns on not to mention the power lines for the heat pump run parallel to the geophone cable. My problems are great and my resources are meager but I sure have one heck of a time trying for the best system to receive those EQs. Sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: BOB BARNS royb1@........... Date: Thu, 11 Aug 2005 10:11:23 -0400 Hi gang, GALVANOMETER Seismograph Earthquake Physics LEHNER GRIFFITH GL-261- Used to Measure Earthquakes Item number: 7537798905 ends Aug 17 I don't know if this is of any interest but a period of 99 secs. caught my eye. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Doug Crice" dcrice@............ Date: Thu, 11 Aug 2005 09:10:26 -0700 A galvanometer in this context is a small mirror attached to a coil of = wire in a magnetic field. When a current flows through the coil, it twists = the mirror (think of a moving coil voltmeter with a mirror instead of a pointer). These units were used in seismic observatories. A focused narrow light = beam would shine on the mirror and be reflected onto a rotating and = translating drum covered with photographic paper. By making the light path long (say = two or more meters), you could achieve significant optical magnification. The long period seismometers generated the small current fed to the galvanometer. Combining all the pieces produced a sensitive seismograph before the days of 24-bit converters or even electronics. Once a day, somebody would change the paper on the drums and develop the previous = day's record.=20 United Electrodynamics in Pasadena was an early manufacturer of seismic instruments. They were bought by Teledyne in the 50's and merged into Teledyne Geotech (now just Geotech). Some of the folks at UED left and started Kinemetrics in the early 60's. Thus ends your history lesson for the day. I have no idea how one could = use these fine instruments today. Doug Crice http://www.geostuff.com Wireless Seismic http://www.wirelessSeismic.com 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 =20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of BOB BARNS Sent: Thursday, August 11, 2005 7:11 AM To: psn mail Subject: ebay auction Hi gang, GALVANOMETER Seismograph Earthquake Physics LEHNER GRIFFITH GL-261- Used to Measure Earthquakes Item number:=20 7537798905 ends Aug 17 I don't know if this is of any interest but a period of 99 secs.=20 caught my eye. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: From: Dennis Wieck dwieck@............ Date: Fri, 12 Aug 2005 11:56:44 -0700 I am in the process of setting up a station. I have a set of Larry's geophones and his amplifier/ filter boards along with his A/D board. I am trying to decide the best place to place my sensors. I live in northwest TN almost on top of the New Madrid Fault. I want to set the geophones up first then I may experiment with some other sensors ( I am also collecting parts to build a S-G sensor ). I have a couple of choices from the reading I have done. I have several questions about trying to decide which would be the "best" place to mount them. I have seen references to mounting them in the crawl space of houses. This would probably be one of the easier options. I can get under he house easily and would have short cable runs. I am not sure how much of the house noise would be picked up in this type location. It is just a dirt base under he house right now.. The second option would to build a small vault probably dug in the ground 3 or 4 feet deep. ( Most likely I would not be able to get to bedrock). I have seen several of this type on he web. I live pretty much in the country on about 5 acres. Most of the land is pretty hilly with a lot of trees. I have seen references saying that you need to be relatively far from trees etc or the wind moving them will affect the sensors. If I do this I would have further to run the cables back to the house. Is it better to have the longer run from the sensors to the boards or to have the A/D output have the longer runs? How much difference would there be with these types of locations? Thanks Dennis __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digging in... From: ChrisAtUpw@....... Date: Fri, 12 Aug 2005 20:26:42 EDT In a message dated 12/08/2005, dwieck@............ writes: I am in the process of setting up a station. I have a set of Larry's geophones and his amplifier / filter boards along with his A/D board. I am trying to decide the best place to place my sensors. I live in northwest TN almost on top of the New Madrid Fault. I want to set the geophones up first then I may experiment with some other sensors ( I am also collecting parts to build a S-G sensor ). I have a couple of choices from the reading I have done. I have several questions about trying to decide which would be the "best" place to mount them. I have seen references to mounting them in the crawl space of houses. This would probably be one of the easier options. I can get under he house easily and would have short cable runs. I am not sure how much of the house noise would be picked up in this type location. It is just a dirt base under the house right now.. Hi Dennis, Is it a timber house or one with brick/stone walls? How many stories? Are they the 4.5 Hz geophones? So long as you stay away from the foundations, you should not get too much house noise. I suggest that you try putting the geophone under the house with the three legs pushed firmly into the soil and see what results you get. Look for significant changes in the background noise between no wind and strong wind conditions and keep some recordings for reference. Also look out for spikes and interference signals, traffic or other noise over 24 hrs. I connected my geophones up to the amplifier in a portable radio and listened with headphones. OK, these signals aren't the seismic ones, but you can often recognise noise sources by ear easier than trying to figure them out from the traces. I start to hear fast cars on the main road at about 1 km. There is a slightly depressed water drain on the main road about 100 yards away which gives thump signals occasionally with passing lorries..... Check for slamming doors and windows, fridge start/stop, cooking loads, central heating timing, wind noise..... If the under house installation is OK, you can scoop out several inches of the topsoil and lay a 3 ft square concrete base in a wood frame. You need to cover it with polythene to keep it 'wet' for maybe a month to 'cure' fully. You use a 50:50 cement and sand mixture, no gravel. Professional installations use a vibrator to remove air bubbles from the wet mix after it is poured. You can get a lot out with a stick. Cement can be quite corrosive in contact with metal, but you can use special paints. You will have to leave adequate space for the thermal / draft screening box if you are definitely going to use a SG horizontal; maybe a longer slab? The second option would to build a small vault probably dug in the ground 3 or 4 feet deep. ( Most likely I would not be able to get to bedrock). I have seen several of this type on the web. I live pretty much in the country on about 5 acres. Most of the land is pretty hilly with a lot of trees. You would have to make it water proof / adequately drained / dry inside. See various websites for ways of doing this. _http://www.guralp.net/services/stations/eskdalemuir/_ (http://www.guralp.net/services/stations/eskdalemuir/) is a professional example in soil which saturates with water. See also _http://seismo.berkeley.edu/seismo/bdsn/instrumentation/guidelines.html_ (http://seismo.berkeley.edu/seismo/bdsn/instrumentation/guidelines.html) I have seen references saying that you need to be relatively far from trees etc or the wind moving them will affect the sensors. If I do this I would have further to run the cables back to the house. Is it better to have the longer run from the sensors to the boards or to have the A/D output have the longer runs? Trees may give broad band noise, but this may be more serious for the longer period instruments. Aim to keep your sensors at a distance equal to the height of the trees, minimum. This is very roughly the expected extent of the roots. Exposed houses will also experience wind noise. You have the problem of long cable runs and probably some lightning protection required for installations away from the house. Some soils have such poor electrical conductivity / are so dry that the effective 'electrical ground surface' is several feet below ground level. All your house electrical wiring is effectively sticking out above the electrical ground! If lightning is a severe local hazard, you can use intermittently charged batteries and a length of fibre optic cable to isolate the digital signals. There are several websites with advice on this for various states. You can bury cables in plastic water pipe. Pipe end fittings designed for water tanks are readily available. Regards, Chris Chapman

In a message dated 12/08/2005, dwieck@............ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I am in=20 the process of setting up a station. I have a set of Larry's geophones
= and=20 his amplifier / filter boards along with his A/D board. I am trying to=20 decide
the best place to place my sensors. I live in northwest TN=20 almost on top of the
New Madrid Fault. I want to set the geophones = ;up=20 first then I may experiment
with some other sensors ( I am also collect= ing=20 parts to build a S-G sensor ). I
have a couple of choices from the=20 reading I have done. I have several questions
about trying to deci= de=20 which would be the "best" place to mount them.

I have seen=20 references to mounting them in the crawl space of houses. This=20 would
probably be one of the easier options. I can get under he=20 house easily and would
have short cable runs. I am not sure h= ow=20 much of the house noise would be picked
up in this type location. = It=20 is just a dirt base under the house right now..

Hi Dennis,

Is it a timber house or one with brick/stone=20 walls? How many stories?

Are they the 4.5 Hz geophones?

So long as you stay away from the foundations,=20= you=20 should not get too much house noise. I suggest that you try putting the= =20 geophone under the house with the three legs pushed firmly into the soil and= see=20 what results you get. Look for significant changes in the background=20 noise between no wind and strong wind conditions and keep some recordin= gs=20 for reference. Also look out for spikes and interference signals, traffic or= =20 other noise over 24 hrs. I connected my geophones up to the amplifier i= n a=20 portable radio and listened with headphones. OK, these signals are= n't=20 the seismic ones, but you can often recognise noise sources by ear easier th= an=20 trying to figure them out from the traces. I start to he= ar=20 fast cars on the main road at about 1 km. There is a slightly depressed wate= r=20 drain on the main road about 100 yards away which gives thump signals=20 occasionally with passing lorries..... Check for slamming doors and=20 windows, fridge start/stop, cooking loads, central heating timing, wind=20 noise.....

If the under house installation is OK, you can=20 scoop out several inches of the topsoil and lay a 3 ft square concrete base=20= in a=20 wood frame. You need to cover it with polythene to keep it 'wet' for maybe a= =20 month to 'cure' fully. You use a 50:50 cement and sand mixture, no=20 gravel. Professional installations use a vibrator to remove air bubbles= =20 from the wet mix after it is poured. You can get a lot out with a stick. Cem= ent=20 can be quite corrosive in contact with metal, but you can use special paints= ..=20 You will have to leave adequate space for the thermal / draft screening= box=20 if you are definitely going to use a SG horizontal; maybe a longer slab? <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2> The second option would to build a small vault probably&nbs= p;dug=20 in the ground 3 or
4 feet deep. ( Most likely I would not be= =20 able to get to bedrock). I have seen
several of this type on the web. I= =20 live pretty much in the country on about 5
acres. Most of the land is=20 pretty hilly with a lot of trees.

You would have to make it water proof / adequat= ely=20 drained / dry inside. See various websites for ways of doing this. http://www.gur= alp.net/services/stations/eskdalemuir/ is=20 a professional example in soil which saturates with water. See also http://seismo.berkeley.edu/seismo/bdsn/instrumentation/guidelines.html

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I have=20 seen references saying that you need to be relatively far from trees etc o= r=20 the wind moving them will affect the sensors. If I do this I would ha= ve=20 further to run the cables back to the house. Is it better to have=20 the longer run from the sensors to the boards or to have the A/= D=20 output have the longer runs?

Trees may give broad band noise, but this may b= e=20 more serious for the longer period instruments. Aim to keep your sensor= s at=20 a distance equal to the height of the trees, minimum. This is very roughly t= he=20 expected extent of the roots. Exposed houses will also experience wind=20 noise.

You have the problem of long cable runs an= d=20 probably some lightning protection required for installations away from= the=20 house. Some soils have such poor electrical conductivity / are so dry that t= he=20 effective 'electrical ground surface' is several feet below ground level. Al= l=20 your house electrical wiring is effectively sticking out above the=20 electrical ground! If lightning is a severe local hazard, you can use=20 intermittently charged batteries and a length of fibre optic cable to isolat= e=20 the digital signals. There are several websites with advice on this for vari= ous=20 states. You can bury cables in plastic water pipe. Pipe end fittings designe= d=20 for water tanks are readily available.

Regards,

Chris Chapman

Subject: Re: Digging in... From: Dennis Wieck dwieck@............ Date: Fri, 12 Aug 2005 21:29:23 -0500 ChrisAtUpw@....... wrote: > Hi Dennis, > > Is it a timber house or one with brick/stone walls? Its brick > How many stories? 2 > > Are they the 4.5 Hz geophones? yes > > So long as you stay away from the foundations, you should not get > too much house noise. I suggest that you try putting the geophone > under the house with the three legs pushed firmly into the soil and > see what results you get. Look for significant changes in the > background noise between no wind and strong wind conditions and keep > some recordings for reference. Also look out for spikes and > interference signals, traffic or other noise over 24 hrs. The good news is I am 200 yards from the nearest road ( except for what comes in my driveway) > I connected my geophones up to the amplifier in a portable radio and > listened with headphones. OK, these signals aren't the seismic ones, > but you can often recognise noise sources by ear easier than trying to > figure them out from the traces. I start to hear fast cars on the main > road at about 1 km. There is a slightly depressed water drain on the > main road about 100 yards away which gives thump signals occasionally > with passing lorries..... Check for slamming doors and windows, fridge > start/stop, cooking loads, central heating timing, wind noise..... > > If the under house installation is OK, you can scoop out several > inches of the topsoil and lay a 3 ft square concrete base in a wood > frame. You need to cover it with polythene to keep it 'wet' for maybe > a month to 'cure' fully. You use a 50:50 cement and sand mixture, no > gravel. Professional installations use a vibrator to remove air > bubbles from the wet mix after it is poured. You can get a lot out > with a stick. Cement can be quite corrosive in contact with metal, but > you can use special paints. You will have to leave adequate space > for the thermal / draft screening box if you are definitely going to > use a SG horizontal; maybe a longer slab? > > The second option would to build a small vault probably dug in > the ground 3 or > 4 feet deep. ( Most likely I would not be able to get to bedrock). > I have seen > several of this type on the web. I live pretty much in the country > on about 5 > acres. Most of the land is pretty hilly with a lot of trees. > > You would have to make it water proof / adequately drained / dry > inside. See various websites for ways of doing this. > http://www.guralp.net/services/stations/eskdalemuir/ is a professional > example in soil which saturates with water. See also > http://seismo.berkeley.edu/seismo/bdsn/instrumentation/guidelines.html > > I have seen references saying that you need to be relatively far > from trees etc or the wind moving them will affect the sensors. If > I do this I would have further to run the cables back to the > house. Is it better to have the longer run from the sensors to > the boards or to have the A/D output have the longer runs? > > Trees may give broad band noise, but this may be more serious for > the longer period instruments. Aim to keep your sensors at a distance > equal to the height of the trees, minimum. This is very roughly the > expected extent of the roots. This is about impossible on my lot. Even the under the house spot would not meet this but would probably be the closest. > Exposed houses will also experience wind noise. > You have the problem of long cable runs and probably > some lightning protection required for installations away from the house. I am used to this. I am a ham and have dealt with tower and coax to my radios grounding. > Some soils have such poor electrical conductivity / are so dry that > the effective 'electrical ground surface' is several feet below ground > level. All your house electrical wiring is effectively sticking out > above the electrical ground! If lightning is a severe local hazard, > you can use intermittently charged batteries and a length of fibre > optic cable to isolate the digital signals. There are several websites > with advice on this for various states. You can bury cables in plastic > water pipe. Pipe end fittings designed for water tanks are readily > available. > Is there a problem with moderate ( probably less than 100 ft) runs between the geophones and the amp/filter/A/D or do I need to remote them ( that adds to the waterproof question)? Thanks Dennis __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: (No subject header) From: "Geoff" gmvoeth@........... Date: Fri, 12 Aug 2005 20:46:25 -0700 > I am in the process of setting up a station. I have a set of Larry's geophones > and his amplifier/ filter boards along with his A/D board. I am trying to decide > the best place to place my sensors. I live in northwest TN almost on top of the > New Madrid Fault. I want to set the geophones up first then I may experiment > with some other sensors ( I am also collecting parts to build a S-G sensor ). I > have a couple of choices from the reading I have done. I have several questions > about trying to decide which would be the "best" place to mount them. > From My experience it is best to have a Geophone underground even 18 inches is better then none but it has to be away from power lines and possibly 15 feet away from any structures You must ground insulate and bond everything and make the Geophone water proof it is humidity and moisture that will be your worst enemy it will corrode the Geophone. Guard any exposed cables from sunlight and being a tripping hazard. If you were really professional you need to know how far to bedrock underground and make sure there are no roads within the same distance as depth to the bedrock....I don't understand why distance to bedrock is so important but I understand bedrock is more resistant to noise sources if you can get your geophones there. I have also found it good to use a shielded cable and run the cable shield to your power supply ground through a small 0.1uf 250V non-electrolytic capacitor. You might also want to use the cap trick to 120V 60Hz ground. I mean ground here and not the neutral wire you got to be careful when playing around with 60Hz noise sources if there is more than 1ma of current leakage it can be a killer it only takes 20uA through the heart to stop it. Be careful with those 60Hz noise sources but they can be canceled out if you are careful. Good luck and tell us what you decided on. Placing the geophone is quite important. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digging in... From: ian ian@........... Date: Sat, 13 Aug 2005 08:20:28 +0100 this all sounds terribly professional. In my last house, I drilled a hole in the top of the property's boundary wall and hammered the geophone spike into it. Then I screwed the geophone back on to its spike. I covered this with 2 plastic containers, one bigger than the other, and put a rock on top to make sure it didn't blow away. This sufficed to protect it from something like the 180" of rain/year that we got. I then had about 50 ft of external co-ax connecting to the filter/amplifier, via a lightning arrestor. I had to get it away from the house as our 2 screaming kids would have made things impossible! This seemed to work fine. I was able to listen in to tantrums of the local volcano 20 miles away, as well as its companions around the state (Hawaii). I too was in a cul-de-sac street with the main road about 200 feet away. I picked up the local traffic on the main road during the day. The only other noise source, which I discovered when I dismantled it to re-locate, was the presence of Gecko eggs inside the plastic container! So, whilst you are waiting for the concrete to cure, you could try something "rough and ready" like the above. Ian Smith Dennis Wieck wrote: > ChrisAtUpw@....... wrote: > >> Hi Dennis, >> >> Is it a timber house or one with brick/stone walls? > > > > Its brick > >> How many stories? > > > 2 > >> >> Are they the 4.5 Hz geophones? > > > > yes > >> >> So long as you stay away from the foundations, you should not get >> too much house noise. I suggest that you try putting the geophone >> under the house with the three legs pushed firmly into the soil and >> see what results you get. Look for significant changes in the >> background noise between no wind and strong wind conditions and keep >> some recordings for reference. Also look out for spikes and >> interference signals, traffic or other noise over 24 hrs. > > > > The good news is I am 200 yards from the nearest road ( except for > what comes in my driveway) > >> I connected my geophones up to the amplifier in a portable radio and >> listened with headphones. OK, these signals aren't the seismic ones, >> but you can often recognise noise sources by ear easier than trying >> to figure them out from the traces. I start to hear fast cars on the >> main road at about 1 km. There is a slightly depressed water drain on >> the main road about 100 yards away which gives thump signals >> occasionally with passing lorries..... Check for slamming doors and >> windows, fridge start/stop, cooking loads, central heating timing, >> wind noise..... >> >> If the under house installation is OK, you can scoop out several >> inches of the topsoil and lay a 3 ft square concrete base in a wood >> frame. You need to cover it with polythene to keep it 'wet' for maybe >> a month to 'cure' fully. You use a 50:50 cement and sand mixture, no >> gravel. Professional installations use a vibrator to remove air >> bubbles from the wet mix after it is poured. You can get a lot out >> with a stick. Cement can be quite corrosive in contact with metal, >> but you can use special paints. You will have to leave adequate space >> for the thermal / draft screening box if you are definitely going to >> use a SG horizontal; maybe a longer slab? >> >> The second option would to build a small vault probably dug in >> the ground 3 or >> 4 feet deep. ( Most likely I would not be able to get to bedrock). >> I have seen >> several of this type on the web. I live pretty much in the country >> on about 5 >> acres. Most of the land is pretty hilly with a lot of trees. >> You would have to make it water proof / adequately drained / dry >> inside. See various websites for ways of doing this. >> http://www.guralp.net/services/stations/eskdalemuir/ is a >> professional example in soil which saturates with water. See also >> http://seismo.berkeley.edu/seismo/bdsn/instrumentation/guidelines.html >> >> I have seen references saying that you need to be relatively far >> from trees etc or the wind moving them will affect the sensors. If >> I do this I would have further to run the cables back to the >> house. Is it better to have the longer run from the sensors to >> the boards or to have the A/D output have the longer runs? >> >> Trees may give broad band noise, but this may be more serious for >> the longer period instruments. Aim to keep your sensors at a distance >> equal to the height of the trees, minimum. This is very roughly the >> expected extent of the roots. > > > > This is about impossible on my lot. Even the under the house spot > would not meet this but would probably be the closest. > >> Exposed houses will also experience wind noise. >> You have the problem of long cable runs and probably some >> lightning protection required for installations away from the house. > > > > I am used to this. I am a ham and have dealt with tower and coax to > my radios grounding. > >> Some soils have such poor electrical conductivity / are so dry that >> the effective 'electrical ground surface' is several feet below >> ground level. All your house electrical wiring is effectively >> sticking out above the electrical ground! If lightning is a severe >> local hazard, you can use intermittently charged batteries and a >> length of fibre optic cable to isolate the digital signals. There are >> several websites with advice on this for various states. You can bury >> cables in plastic water pipe. Pipe end fittings designed for water >> tanks are readily available. >> > > > Is there a problem with moderate ( probably less than 100 ft) runs > between the geophones and the amp/filter/A/D or do I need to remote > them ( that adds to the waterproof question)? > > Thanks > Dennis > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digging in... From: ChrisAtUpw@....... Date: Sat, 13 Aug 2005 11:10:35 EDT In a message dated 13/08/2005, dwieck@............ writes: > Is it a timber house or one with brick/stone walls? Its brick > How many stories? 2 > Are they the 4.5 Hz geophones? yes Hi Dennis, I would be optimistic about an underfloor location. Just keep away from the water supply and waste water pipes and from the foundations. Suggest that you try it out as your first option? The good news is I am 200 yards from the nearest road (except for what comes in my driveway) That will probably be fine. > I connected my geophones up to the amplifier in a portable radio and > listened with headphones. OK, these signals aren't the seismic ones, > but you can often recognise noise sources by ear easier than trying to > figure them out from the traces. I start to hear fast cars on the main > road at about 1 km. There is a slightly depressed water drain on the > main road about 100 yards away which gives thump signals occasionally > with passing lorries..... Check for slamming doors and windows, fridge > start/stop, cooking loads, central heating timing, wind noise..... Do 'have a listen', see what you can pick up and also take a seismic recording to find any associated signals. > Trees may give broad band noise, but this may be more serious for > the longer period instruments. Aim to keep your sensors at a distance > equal to the height of the trees, minimum. This is about impossible on my lot. Even the under the house spot would not meet this but would probably be the closest. > You have the problem of long cable runs and probably > some lightning protection required for installations away from the house. >> I am used to this. I am a ham and have dealt with tower and coax to my radios grounding. Great. There is a lot of ham literature on protection for radio systems. Is there a problem with moderate (probably less than 100 ft) runs between the geophones and the amp/filter/A/D or do I need to remote them (that adds to the waterproof question)? This depends a lot on your soil conductivity. Wiring under the house is likely to be partly shielded by the house 'earth'. 100 ft is quite a long external 'aerial'. I would be inclined to fit some lightning protection where the cable enters the house, especially if lightning is a 'problem' in your area. A burnt out seismic system + computer would be expensive. Remember that you get ground currents for quite some distance around a lightning strike. Is the utility power wiring to your house below ground or on poles? Elevated wiring does tend to pick up stronger lightning surges, sometimes from many miles away. Regards, Chris Chapman

In a message dated 13/08/2005, dwieck@............ writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>> Is it a timber house or one with brick/st= one=20 walls?
Its brick
> How many stories?
2
> &nb= sp;=20 Are they the 4.5 Hz geophones?
yes

Hi Dennis,

I would be optimistic about an underfloor locat= ion.=20 Just keep away from the water supply and waste water pipes and from the=20 foundations. Suggest that you try it out as your first option?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The good=20 news is I am 200 yards from the nearest road (except for what
comes in= my=20 driveway)

That will probably be fine.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>> I=20 connected my geophones up to the amplifier in a portable radio and
>= ;=20 listened with headphones. OK, these signals aren't the seismic ones,
&= gt;=20 but you can often recognise noise sources by ear easier than trying to=20
> figure them out from the traces. I start to hear fast cars on the= =20 main
> road at about 1 km. There is a slightly depressed water drai= n on=20 the
> main road about 100 yards away which gives thump signals=20 occasionally
> with passing lorries..... Check for slamming doors a= nd=20 windows, fridge
> start/stop, cooking loads, central heating timing= ,=20 wind noise.....

Do 'have a listen', see what you can pick up an= d=20 also take a seismic recording to find any associated signals.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>> Trees may give broad band noise, but= this=20 may be more serious for
> the longer period instruments. Aim to kee= p=20 your sensors at a distance
> equal to the height of the trees, mini= mum.=20

This is about impossible on my lot. Even the under the house spot=20 would
not meet this but would probably be the closest.

> You have the problem of long cable runs and= =20 probably
> some lightning protection required for installations away=20= from=20 the house.

>> I am used to this. I am a ham and have dealt with tow= er and=20 coax to my
radios grounding.

Great. There is a lot of ham literature on=20 protection for radio systems.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Is there=20 a problem with moderate (probably less than 100 ft) runs
between the=20 geophones and the amp/filter/A/D or do I need to remote them
(that add= s to=20 the waterproof question)?

This depends a lot on your soil conductivity.=20 Wiring under the house is likely to be partly shielded by the house 'earth'.= 100=20 ft is quite a long external 'aerial'. I would be inclined to fit some lightn= ing=20 protection where the cable enters the house, especially if lightning is a=20 'problem' in your area. A burnt out seismic system + computer would be=20 expensive. Remember that you get ground currents for quite some distance aro= und=20 a lightning strike.

Is the utility power wiring to your house below= =20 ground or on poles? Elevated wiring does tend to pick up stronger= =20 lightning surges, sometimes from many miles away.

Regards,

Chris Chapman

Subject: Re: Digging in... From: Dennis Wieck dwieck@............ Date: Sat, 13 Aug 2005 11:16:14 -0500 > > I would be optimistic about an underfloor location. Just keep away > from the water supply and waste water pipes and from the foundations. > Suggest that you try it out as your first option? Thats what I am considering as the first option. It certainly would be quicker / easier. This depends a lot on your soil conductivity. Wiring under the house is likely to be partly shielded by the house 'earth'. 100 ft is quite a long external 'aerial'. It may be less depending on where I decide to place it. > I would be inclined to fit some lightning protection where the cable > enters the house, especially if lightning is a 'problem' in your area. It is. I have experience with the "ground" effects of lightning. We had a ground strike to the metal reinforcement in a runway at an airport I used to work with, it took out about half of our runway light system with it. We knew it hit the runway by the damage on it. > > Is the utility power wiring to your house below ground or on > poles? Elevated wiring does tend to pick up stronger lightning > surges, sometimes from many miles away. > Mostly poles although the last part is underground. > Thanks Dennis __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digging in... From: Dennis Wieck dwieck@............ Date: Sat, 13 Aug 2005 11:20:20 -0500 ian wrote: > > So, whilst you are waiting for the concrete to cure, you could try > something "rough and ready" like the above. > > Ian Smith > Thanks. I do think I will try something simple first. May try to do a "vault when it starts to cool down some. Dennis __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digging in... From: Gordon Couger gcouger@.......... Date: Sat, 13 Aug 2005 16:07:05 -0500 ChrisAtUpw@....... wrote: > In a message dated 13/08/2005, dwieck@............ writes: > > > Is it a timber house or one with brick/stone walls? > Its brick > > How many stories? > 2 > > Are they the 4.5 Hz geophones? > yes > > Hi Dennis, > > > > You have the problem of long cable runs and probably > > some lightning protection required for installations away from the house. > >> I am used to this. I am a ham and have dealt with tower and coax to my > radios grounding. > > Great. There is a lot of ham literature on protection for radio systems. > > Is there a problem with moderate (probably less than 100 ft) runs > between the geophones and the amp/filter/A/D or do I need to remote them > (that adds to the waterproof question)? > > This depends a lot on your soil conductivity. Wiring under the house is likely to be partly shielded by the house 'earth'. 100 ft is quite a long external 'aerial'. I would be inclined to fit some lightning protection where the cable enters the house, especially if lightning is a 'problem' in your area. A burnt out seismic system + computer would be expensive. Remember that you get ground currents for quite some distance around a lightning strike. > > Is the utility power wiring to your house below ground or on poles? Elevated wiring does tend to pick up stronger lightning surges, sometimes from many miles away. > Regards, > > Chris Chapman To beat long cable runs and the associated problems wireless data links are just becoming a reasonably priced off the rack solutions that is reasonably easy to put in to practice. Using directional antennas Zigbee and BlueTooth can work several hundred yard in the clear. I it a bit more than most of us would want to undertake but for one very quite site http://www.couger.com/ranch.gif that is two miles off a lightly traveled high way and has NO traffic at night I have to have a wireless link to the phone lines so I can be several miles away from power lines as well. I will probably use something with more range than BlueTooht some hams are getting 3 miles with 802.11 B wireless cards made for office automation. That would take a large solar powered installation but in the scope of what I have in mind. Maxsteam has good off the rack stuff that I know works. http://www.maxstream.net/products/index.php If you want plug and play. Cheers Gordon Gordon Couger Stillwater, OK www.couger.com/gcouger __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digging in... From: ChrisAtUpw@....... Date: Sat, 13 Aug 2005 20:43:11 EDT In a message dated 13/08/2005, gcouger@.......... writes: To beat long cable runs and the associated problems wireless data links are just becoming a reasonably priced off the rack solutions that is reasonably easy to put in to practice. Using directional antennas Zigbee and BlueTooth can work several hundred yard in the clear. Maxsteam has good off the rack stuff that I know works. http://www.maxstream.net/products/index.php If you want plug and play. Cheers Gordon Hi Gordon, Thanks for the feedback. I am aware of the radio links that have been / are becoming available. If you really need a long link and are happy to fund it, fine, but do consider all the options. UHF radio links do require some skill to implement and are not entirely 'fit and forget'. They may impose limits on the receiving computer, both for RAM provision and on the processing rate, particularly when using encrypted data. You are usually running several linked applications for seismic data recording. Check that you can have full 'preset' control of the transmitted data rate. This is not always available. (e.g. If I run my 56 K modem at more than 38 K, it 'drops out' several times an hour / performs like a geriatric snail - due to the length of the line - according to the sevice provider.) You need the link to work 100% in all weather conditions. High speed UHF signals may become garbled in woodland locations, especially during rain or snow / where you get strong reflected multipath signals. However, it still leaves you with a remote power supply problem and you may need links both ways for seismic work. The link to an ADC is usually two way. Low noise amplifiers tend to have significant power consumption. Do you need to buy battery operated power supplies / batteries / solar panels? You may then fit an ADC and send digital signals, or you can generate a frequency modulated signals which are demodulated at the receiver, but this may require several channels of additional electronics. Somewhere along the line you have to have a time reference on a 24/7 basis to 1 second, or preferably to 0.1 second, linked to the ADC sample timing. GPS receivers tend to be power hungry, location sensitive and still moderately expensive. The internal software clocks which are usually fitted to computers are nowhere near accurate enough. On my 'new' computer, I can't rely on it to within 20 secs per day. Updating the clock every hour is just not adequate. Some of the web time services have significant and variable signal delays. (I bought a radio corrected LCD quartz clock.) A 1 sec error on a seismic signal represents about 10 km uncertainty. Do check on the total $$$ cost / benefit if you are considering a radio system. Check if there are similar radio systems operating locally over similar distances? Are there any adverse local problems, like other radio transmitters / interference sources / obstructing metal mesh fences? Try to avoid 'buying trouble'. Regards, Chris Chapman

In a message dated 13/08/2005, gcouger@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>To beat=20 long cable runs and the associated problems wireless data links
are ju= st=20 becoming a reasonably priced off the rack solutions that is
reasonably= =20 easy to put in to practice. Using directional antennas Zigbee
and=20 BlueTooth can work several hundred yard in the clear.
Maxsteam has goo= d=20 off the rack stuff that I know works.=20
http://www.maxstream.net/products/index.php If you want plug and=20 play.
Cheers
Gordon

Hi Gordon,

Thanks for the feedback.

I am aware of the radio links that have been /=20= are=20 becoming available. If you really need a long link and are happy to fund it,= =20 fine, but do consider all the options.

UHF radio links do require some skill to implem= ent=20 and are not entirely 'fit and forget'. They may impose limits on the receivi= ng=20 computer, both for RAM provision and on the processing rate, particularly wh= en=20 using encrypted data. You are usually running several linked applications fo= r=20 seismic data recording. Check that you can have full 'preset' control of the= =20 transmitted data rate. This is not always available. (e.g. If I run my 56 K=20 modem at more than 38 K, it 'drops out' several times an hour / performs lik= e a=20 geriatric snail - due to the length of the line - according to the sevice=20 provider.) You need the link to work 100% in all weather conditions. Hi= gh=20 speed UHF signals may become garbled in woodland locations, especially durin= g=20 rain or snow / where you get strong reflected multipath signals.

However, it still leaves you with a remote powe= r=20 supply problem and you may need links both ways for seismic work. The link t= o an=20 ADC is usually two way. Low noise amplifiers tend to have significant power=20 consumption. Do you need to buy battery operated power supplies /=20 batteries / solar panels? You may then fit an ADC and send digital sign= als,=20 or you can generate a frequency modulated signals which are demodulated= at=20 the receiver, but this may require several channels of additional electronic= s.=20

Somewhere along the line you have to have=20 a time reference on a 24/7 basis to 1 second, or preferably to 0.1= =20 second, linked to the ADC sample timing. GPS receivers tend to be power hung= ry,=20 location sensitive and still moderately expensive. The internal softwar= e=20 clocks which are usually fitted to computers are nowhere near accurate=20 enough. On my 'new' computer, I can't rely on it to within 20 secs= per=20 day. Updating the clock every hour is just not adequate. Some of the we= b=20 time services have significant and variable signal delays. (I bought a radio= =20 corrected LCD quartz clock.) A 1 sec error on a seismic signal represents ab= out=20 10 km uncertainty.

Do check on the total $$$ cost / benefit if you= are=20 considering a radio system. Check if there are similar radio systems operati= ng=20 locally over similar distances? Are there any adverse local problems, like o= ther=20 radio transmitters / interference sources / obstructing metal mesh fences? T= ry=20 to avoid 'buying trouble'.

Regards,

Chris Chapman

Subject: Re: Digging in... From: Gordon Couger gcouger@.......... Date: Sun, 14 Aug 2005 04:12:30 -0500 ChrisAtUpw@....... wrote: > In a message dated 13/08/2005, gcc-at-couger.com writes: > > To beat long cable runs and the associated problems wireless data links > are just becoming a reasonably priced off the rack solutions that is > reasonably easy to put in to practice. Using directional antennas > ZigBee > and BlueTooth can work several hundred yard in the clear. > Maxsteam has good off the rack stuff that I know works. > http://www.maxstream.net/products/index.php If you want plug and play. > Cheers > Gordon > > Hi Gordon, > > Thanks for the feedback. > I am aware of the radio links that have been / are becoming > available. If you really need a long link and are happy to fund it, > fine, but do consider all the options. > UHF radio links do require some skill to implement and are not > entirely 'fit and forget'. They may impose limits on the receiving > computer, both for RAM provision and on the processing rate, > particularly when using encrypted data. You are usually running several > linked applications for seismic data recording. Check that you can have > full 'preset' control of the transmitted data rate. This is not always > available. (e.g. If I run my 56 K modem at more than 38 K, it 'drops > out' several times an hour / performs like a geriatric snail - due to > the length of the line - according to the service provider.) You need the > link to work 100% in all weather conditions. High speed UHF signals may > become garbled in woodland locations, especially during rain or snow / > where you get strong reflected multipath signals. > However, it still leaves you with a remote power supply problem and > you may need links both ways for seismic work. The link to an ADC is > usually two way. Low noise amplifiers tend to have significant power > consumption. Do you need to buy battery operated power supplies / > batteries / solar panels? You may then fit an ADC and send digital > signals, or you can generate a frequency modulated signals which are > demodulated at the receiver, but this may require several channels of > additional electronics. > Somewhere along the line you have to have a time reference on a 24/7 > basis to 1 second, or preferably to 0.1 second, linked to the ADC sample > timing. GPS receivers tend to be power hungry, location sensitive and > still moderately expensive. The internal software clocks which > are usually fitted to computers are nowhere near accurate enough. On my > 'new' computer, I can't rely on it to within 20 secs per day. Updating > the clock every hour is just not adequate. Some of the web time services > have significant and variable signal delays. (I bought a radio corrected > LCD quartz clock.) A 1 sec error on a seismic signal represents about 10 > km uncertainty. > Do check on the total $$$ cost / benefit if you are considering a > radio system. Check if there are similar radio systems operating locally > over similar distances? Are there any adverse local problems, like other > radio transmitters / interference sources / obstructing metal mesh > fences? Try to avoid 'buying trouble'. > > Regards, > > Chris Chapman Hi Chris, I don't think we are to the point that it either easy or cheap to run out an get a wireless link for home built toys. But it time to start thinking about them and including them in thoughts and plans. Doing a wireless link is a large undertaking. I did the first work for Datalink Systems www.rfdata.net wireless stuff and the power supplies were designed to for 5 volts at 3 amps to accommodate all the various stuff we supported. However 5V 1A would meet most installation requirements. They were 30% over designed hopefully to be longer lived when run in temperatures beyond their rating. We couldn't get parts to run at the temperature encountered in some installations in the tropics. so we were careful to choose chips that had good reputations for running hot environments and using the highest temperature rated parts we could find. Using chips like the 68HC11 that when run at half speed has a reasonable life at 200 c. We strictly warned against installing things in overly hostile environments but we did our best to make them live there. Going wireless some noise problems improve. Using long lever arms made of light beams can mechanically amplify the signal but it change the noise problem form electronics to mechanics. Using microwave particularly the 2.4 GHz band heavy rain and wet foliage is always going to be a problem. There is probably not a worse frequency for rain interference in the low GHz band than they chose for ZigBee. That can be over come with higher gain antennas and more power. I would use Zigbee because it is cheap, I know it works and the data format is not set in stone and it is easy to implement SLIP or something similar that you can use to encapsulate any kind of format you want with minimum over head and is easy to modify in the future. Today I can buy 60 MHz ARM computer board from New Micros off the rack for $29 bucks high speed SPI or I2c A/D coverers, memory are cheap and 3o yard ZigBee link that I can be programmed to use a modification of SLIP http://www.faqs.org/rfcs/rfc1055.html to implement a limited to store and forward method for capability for digitized data to insure data integrity. Made from comments it could be very cost effective about $100 for the computer and about the same or a bit less for the solar power. Adding GPS for time somewhere in the system would cost around $50 bucks. Less for an old Rockwell Jupiter but that needs to be off the solar power as it draws 200 ma with out a amplified antenna but the receiving station could use it to send a heart beat time message every second to update all the clocks on the warless network. If you make if from off the shelf parts it will run about 500 hundred to a thousand dollars. Going to UHF radios limits your band width to the IF frequency of the radio. Of course with ARM computers being a cheap as they are you can put more compression and computing power at the remote site than I ever dreamed of. Embedded computing have changed more in the last 2 or 3 years than in the past 10 as far and cost and affordability and increase in computing power and wireless speed that a serious tinker can buy. Cheers Gordon __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: BOB BARNS royb1@........... Date: Sun, 14 Aug 2005 10:19:36 -0400 Hi gang, AS1 Seismometer, Excellent Condition Item number: 6200926939 ends Aug 20 This is a vertical but has a rather short period. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction From: John or Jan Lahr JohnJan@........ Date: Sun, 14 Aug 2005 10:53:26 -0700 The AS1 works amazingly well for such a simple mechanical system with moving magnet. I've posted information here on the system: http://jclahr.com/science/psn/as1/ However $150 is quite steep for a used transducer without amplifier/filter/AD unit. Cheers, John At 07:19 AM 8/14/2005, you wrote: >Hi gang, > > AS1 Seismometer, Excellent Condition > Item number: 6200926939 ends Aug 20 > >This is a vertical but has a rather short period. >Bob > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body of the >message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction From: "Geoff" gmvoeth@........... Date: Sun, 14 Aug 2005 11:52:08 -0700 > The AS1 works amazingly well for such a simple mechanical system with > moving magnet. > I've posted information here on the system: http://jclahr.com/science/psn/as1/ That actually looks like a very nice little machine but they could improve the magnet by having two opposing magnets facing each other with alternate poles on each side of the coil then the strength of the magnetic field alone should be good enough for the damping given a load resistor of about 2.414 of the coil resistance. If the filter were reduced to between 2Hz and 20 seconds you would have an ideal standard system for any Amateur out there. Such a filter would need to block all frequencies over about 10 HZ to prevent problems using slower sample rates like the tic rate of an IBM style computer of 65536/3600 samples per hour. It is a shame though that the pros do not make a cheaper geophone for amateurs to use. They do not need to be made to the same specs the pros use only need to have a free period between 2 seconds and one hertz. Amateurs do not need ruggedized equipment like military or industry. gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Kareem at HeyJooJoo" system98765@............. Date: Sun, 14 Aug 2005 11:58:20 -0700 This particular unit is more suited for local event records, right? Kareem -----Original Message----- From: John or Jan Lahr [mailto:JohnJan@......... Sent: Sunday, August 14, 2005 10:53 AM To: psn-l@.............. Subject: Re: ebay auction The AS1 works amazingly well for such a simple mechanical system with moving magnet. I've posted information here on the system: http://jclahr.com/science/psn/as1/ However $150 is quite steep for a used transducer without amplifier/filter/AD unit. Cheers, John At 07:19 AM 8/14/2005, you wrote: >Hi gang, > > AS1 Seismometer, Excellent Condition > Item number: 6200926939 ends Aug 20 > >This is a vertical but has a rather short period. >Bob > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body of >the message (first line only): unsubscribe See >http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: John or Jan Lahr JohnJan@........ Date: Sun, 14 Aug 2005 13:53:11 -0700 Hi Kareem, Without strong filtering to enhance the longer periods, this unit would be unable to see teleseismic surface waves. The filter/amplifier that is sold with the AS1 does manage to pull out larger surface waves. After a large event, check out the records posted here in near-real time: http://jclahr.com/science/psn/as1/heli/allas1.php (Many school stations are not operating during the summer.) The Sumatra records are posted here: http://jclahr.com/science/psn/as1/indonesia04/as1indo.html and records from a 6.7 in the Cayman Islands here: http://jclahr.com/science/psn/as1/heli/cayman.html Often when a long period instrument picks up clear 20-second surface waves the AS1 will only see waves in the 12- to 15-second range. Cheers, John At 11:58 AM 8/14/2005, you wrote: >This particular unit is more suited for local event records, right? > >Kareem > >-----Original Message----- >From: John or Jan Lahr [mailto:JohnJan@......... >Sent: Sunday, August 14, 2005 10:53 AM >To: psn-l@.............. >Subject: Re: ebay auction > >The AS1 works amazingly well for such a simple mechanical system with moving >magnet. >I've posted information here on the system: >http://jclahr.com/science/psn/as1/ > >However $150 is quite steep for a used transducer without >amplifier/filter/AD unit. .. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Kareem at HeyJooJoo" system98765@............. Date: Sun, 14 Aug 2005 15:57:52 -0700 Ah hah. Thanks John. I'm always trying to find a longer period system as I don't have the time to build one - but would really, really like to. My system is a vertical 4.5Hz one. Kareem -----Original Message----- From: John or Jan Lahr [mailto:JohnJan@......... Sent: Sunday, August 14, 2005 1:53 PM To: psn-l@.............. Subject: RE: ebay auction Hi Kareem, Without strong filtering to enhance the longer periods, this unit would be unable to see teleseismic surface waves. The filter/amplifier that is sold with the AS1 does manage to pull out larger surface waves. After a large event, check out the records posted here in near-real time: http://jclahr.com/science/psn/as1/heli/allas1.php (Many school stations are not operating during the summer.) The Sumatra records are posted here: http://jclahr.com/science/psn/as1/indonesia04/as1indo.html and records from a 6.7 in the Cayman Islands here: http://jclahr.com/science/psn/as1/heli/cayman.html Often when a long period instrument picks up clear 20-second surface waves the AS1 will only see waves in the 12- to 15-second range. Cheers, John At 11:58 AM 8/14/2005, you wrote: >This particular unit is more suited for local event records, right? > >Kareem > >-----Original Message----- >From: John or Jan Lahr [mailto:JohnJan@......... >Sent: Sunday, August 14, 2005 10:53 AM >To: psn-l@.............. >Subject: Re: ebay auction > >The AS1 works amazingly well for such a simple mechanical system with >moving magnet. >I've posted information here on the system: >http://jclahr.com/science/psn/as1/ > >However $150 is quite steep for a used transducer without >amplifier/filter/AD unit. .. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction From: ChrisAtUpw@....... Date: Sun, 14 Aug 2005 19:05:17 EDT In a message dated 14/08/2005, royb1@........... writes: AS1 Seismometer, Excellent Condition Item number: 6200926939 ends Aug 20 This is a vertical but has a rather short period. Bob This unit has NO electronics, so it is limited to it's natural response of ~1.5 sec and shorter periods. A specialised amplifier + ADC + processor is sold with these units to boost the low frequency response out to about 15 sec. I don't know of an available circuit for DIY. If the integral knife edge on the boom gets damaged, it won't work properly. I never pay more than 50% of the cost price of a secondhand item which has no warranty. Regards, Chris Chapman

In a message dated 14/08/2005, royb1@........... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2> AS1 Seismometer, Excellent Condition
= =20 Item number: 6200926939 ends Aug 20

This= is=20 a vertical but has a rather short period.
Bob

This unit has NO electronics, so it is limited=20= to=20 it's natural response of ~1.5 sec and shorter periods.

A specialised amplifier + ADC + processor = is=20 sold with these units to boost the low frequency response out to about=20 15 sec. I don't know of an available circuit for DIY. If the integral k= nife=20 edge on the boom gets damaged, it won't work properly.

I never pay more than 50% of the cost price of=20= a=20 secondhand item which has no warranty.

Regards,

Chris Chapman

Subject: Re: Digging in... From: ChrisAtUpw@....... Date: Mon, 15 Aug 2005 16:55:41 EDT In a message dated 14/08/2005, gcouger@.......... writes: Hi Chris, I don't think we are to the point that it either easy or cheap to run out and get a wireless link for home built toys. But it time to start thinking about them and including them in thoughts and plans. We seem to getting nearer, slowly, but I'm not interested in toys. Doing a wireless link is a large undertaking. I did the first work for Datalink Systems www.rfdata.net wireless stuff and the power supplies were designed to for 5 volts at 3 amps to accommodate all the various stuff we supported. However 5V 1A would meet most installation requirements. 5 watts average would require quite a large size battery and solar cell array. >> Going wireless some noise problems improve. Using long lever arms made of light beams can mechanically amplify the signal but it change the noise problem from electronics to mechanics. This stopped being a viable seismic technique by the early 1970s and got replaced with sensors which had far better resolution. Like down to 1/100 nano metre. You still had photocell noise with the light beams. Semiconductor lasers are very noisy as well as having divergent beams. This was OK for photographic recording, but who wants to use it these days? particularly when you can both filter and display a chosen digital recording? Using microwave particularly the 2.4 GHz band heavy rain and wet foliage is always going to be a problem. There is probably not a worse frequency for rain interference in the low GHz band than they chose for ZigBee. That can be over come with higher gain antennas and more power. Or you could try a hamming code. I would use Zigbee because it is cheap, I know it works and the data format is not set in stone Today I can buy 60 MHz ARM computer board from New Micros off the rack for $29 bucks high speed SPI or I2c A/D coverers, memory are cheap and 30 yard ZigBee link that I can be programmed to use a modification of SLIP http://www.faqs.org/rfcs/rfc1055.html to implement a limited to store and forward method for capability for digitized data to insure data integrity. Made from components it could be very cost effective about $100 for the computer and about the same or a bit less for the solar power. And about the same for the ADC and.....$$$ A 12 bit ADC with noise is not much use for a seismometer. The 16 bit ADCs have two bits of noise on them as supplied. This could be averaged out, but it hasn't been done. Adding GPS for time somewhere in the system would cost around $50 bucks. For just the receiver. Then you have to buy the aerial and also an interface board. The cheapest that I know about is $140 from psn. Less for an old Rockwell Jupiter but that needs to be off the solar power as it draws 200 ma without a amplified antenna but the receiving station could use it to send a heart beat time message every second to update all the clocks on the wireless network. If you make if from off the shelf parts it will run about 500 hundred to a thousand dollars. I may be getting old, but I am not getting stupid. It would be great to see timing systems available which use WWVB and a trimmed quartz crystal, like on the small radio clocks. Preferably for somewhere about $30. There is absolutely no requirement for microsecond accuracy with 10 Hz seismic waves. Alternatively, it would be nice to see the computer bodgers put a somehere near decent clock on their boards. Going to UHF radios limits your band width to the IF frequency of the radio. ?? While you can get superhet modules, many of them just use a surface wave filter. Of course with ARM computers being a cheap as they are you can put more compression and computing power at the remote site than I ever dreamed of. You won't get any praise from me for making things complicated. I look for reliability, well written software and overall performance, but I don't see much of it yet. One radio comms programme requires 30 MB of RAM. With systems like that about, it looks like real progress is going to be slow. One technique which I have used with success in the past for distances up to 100 yds line of sight is pulsed IR optical links with Fresnel lenses. Regards, Chris Chapman.

In a message dated 14/08/2005, gcouger@.......... writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Hi=20 Chris,

I don't think we are to the point that it either easy or che= ap=20 to run out and get a wireless link for home built toys. But it time to sta= rt=20 thinking about them and including them in thoughts and=20 plans.

We seem to getting nearer, slowly, but I'm= not=20 interested in toys.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Doing a=20 wireless link is a large undertaking. I did the first work for Datalink=20 Systems www.rfdata.net wireless stuff and the power supplies were designed= to=20 for 5 volts at 3 amps to accommodate all the various stuff we supported.=20 However 5V 1A
would meet most installation=20 requirements.

5 watts average would require quite a large siz= e=20 battery and solar cell array.

>> Going wireless some noise problems=20 improve. Using long lever arms made of light beams can mechanically amp= lify=20 the signal but it change the noise problem from electronics to=20 mechanics.

This stopped being a viable seismic technique b= y=20 the early 1970s and got replaced with sensors which had far better resolutio= n.=20 Like down to 1/100 nano metre. You still had photocell noise with the light=20 beams. Semiconductor lasers are very noisy as well as having divergent beams= ..=20 This was OK for photographic recording, but who wants to use it these days?=20 particularly when you can both filter and display a chosen digital=20 recording?

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Using=20 microwave particularly the 2.4 GHz band heavy rain and wet foliage is alwa= ys=20 going to be a problem. There is probably not a worse frequency for rain=20 interference in the low GHz band than they chose for ZigBee. That can be o= ver=20 come with higher gain antennas and more power.

Or you could try a hamming code.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I would=20 use Zigbee because it is cheap, I know it works and the data format is not= set=20 in stone

Today I can buy 60 MHz ARM computer board from New Micros= off=20 the rack for $29 bucks high speed SPI or I2c A/D coverers, memory are chea= p=20 and 30 yard ZigBee link that I can be programmed to use a modification of=20= SLIP=20
http://www.faqs.org/rfcs/rfc1055.html to implement a limited to store=20= and=20 forward method for capability for digitized data to insure data integrity.= =20 Made from components it could be very cost effective about $100 for the=20 computer and about the same or a bit less for the solar=20 power.

And about the same for the ADC and.....$$$

A 12 bit ADC with noise is not much u= se=20 for a seismometer. The 16 bit ADCs have two bits of noise on them as supplie= d.=20 This could be averaged out, but it hasn't been done.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Adding=20 GPS for time somewhere in
the system would cost around $50 bucks.=20

For just the receiver. Then you have to buy the= =20 aerial and also an interface board.

The cheapest that I know about is $140 from=20 psn.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Less for=20 an old Rockwell Jupiter but that needs to be off the solar power as it dra= ws=20 200 ma without a amplified antenna but the receiving station could use it=20= to=20 send a heart beat time message every second to update all the clocks on th= e=20 wireless network. If you make if from off the shelf parts it will run abou= t=20 500 hundred to a thousand dollars.

I may be getting old, but I am not getting=20 stupid.

It would be great to see timing systems availab= le=20 which use WWVB and a trimmed quartz crystal, like on the small radio clocks.= =20 Preferably for somewhere about $30. There is absolutely no requirement for=20 microsecond accuracy with 10 Hz seismic waves.

Alternatively, it would be nice to see the= =20 computer bodgers put a somehere near decent clock on their boards. <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Going to=20 UHF radios limits your band width to the IF frequency of the radio.=20

?? While you can get superhet modules, many of=20= them=20 just use a surface wave filter.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Of=20 course with ARM computers being a cheap as they are you can put more=20 compression and computing power at the remote site than I ever dreamed=20 of.

You won't get any praise from me for making thi= ngs=20 complicated. I look for reliability, well written software and overall=20 performance, but I don't see much of it yet. One radio comms programme requi= res=20 30 MB of RAM. With systems like that about, it looks like real progress is g= oing=20 to be slow.

One technique which I have used with succes= s in=20 the past for distances up to 100 yds line of sight is pulsed IR optical link= s=20 with Fresnel lenses.

Regards,

Chris Chapman.

Subject: Re: Digging in... From: Larry Cochrane lcochrane@.............. Date: Tue, 16 Aug 2005 02:46:38 -0700 Hi Everyone, >> >> Adding GPS for time somewhere in >> the system would cost around $50 bucks. > > For just the receiver. Then you have to buy the aerial and also an > interface board. > The cheapest that I know about is $140 from psn. I am now selling a Garmin GPS 18 OEM timing sensor that will work with my A/D board, the cost is under $100.00 USD. See http://www.seismicnet.com/gps/gps18.html for more information. I do not know of a GPS receiver under $50.00 that has the 1 PPS signal needed for accurate timing. Regards, Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: low cost GPS timing modules From: "Charles R. Patton" charles.r.patton@........ Date: Tue, 16 Aug 2005 09:13:13 -0700 Larry, On EBAY, the Rockwell Jupiter series modules have been consistently available for quite some time (many months). I searched today and found two sellers selling them for $35 (Buy-It-Now) which has generally been the going price. The first: http://cgi.ebay.com/Rockwell-Jupiter-GPS-OEM-Receiver-Module-APRS-AVL_W0QQitemZ5797368523QQcategoryZ4668QQssPageNameZWDVWQQrdZ1QQcmdZViewItem is a bit older model, while: http://cgi.ebay.com/Rockwell-Jupiter-GPS-Receiver-12-CH-Board-NEW-w-BONUS_W0QQitemZ5797806498QQcategoryZ4668QQssPageNameZWDVWQQrdZ1QQcmdZViewItem is one generation later. But to the best of my knowledge, all Jupiter series boards have both a 1 PPS and 10 KHz output. The second seller above is offering a *TU30-D140-221* *with antenna*.and its spec sheet definitely shows both timing outputs. The 10 KHz is great for locking local frequency standards to. Now there is a newer version, the Jupiter-T, that is specifically designed for timing use. I bought one of those for about $90 new from a company in Florida. Anyway the comment is that there seems to be a fairly consistent supply of these older Jupiter series of boards that are available for about $35. The second deal is really great because the antenna is included, however I don't think he has a big supply, although you could approach him and find out. Regards, Charles Patton Larry Cochrane wrote: > Hi Everyone, > >>> >>> Adding GPS for time somewhere in >>> the system would cost around $50 bucks. >> >> >> For just the receiver. Then you have to buy the aerial and also >> an interface board. >> The cheapest that I know about is $140 from psn. > > > I am now selling a Garmin GPS 18 OEM timing sensor that will work with > my A/D board, the cost is under $100.00 USD. See > http://www.seismicnet.com/gps/gps18.html for more information. I do > not know of a GPS receiver under $50.00 that has the 1 PPS signal > needed for accurate timing. > > Regards, > Larry Cochrane > Redwood City, PSN > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with the body of > the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Garmin Gps From: "Francesco" fra.nuc@........... Date: Tue, 16 Aug 2005 19:17:41 +0200 Hello Larry. Can I use the Garmin GPS 18 LVC with my Psn AD 16 Rev 2 board (directly into the serial port of SdrServer PCdos) ? My old antenna for the Motorola Oncore Gps is totally unusable. Regards Francesco Italy. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Serial SDR From: Charlie Plyler cplyler@.......... Date: Thu, 18 Aug 2005 21:09:31 -0400 Hello Larry, I need to get in touch with you concerning ordering the SDR Serial board. Please send me a contact number via this address or a way I may get up you. Thanks, Charlie Plyler __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Heliplots with MathCad From: Mike Speed mike8s2@......... Date: Sat, 20 Aug 2005 05:55:51 -0700 (PDT) How can I use mathcad to create a heli-plot. The polar plot does not work. Thanks, Greg __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Plotting raw data with Mathcad From: Mike Speed mike8s2@......... Date: Sat, 20 Aug 2005 14:35:46 -0700 (PDT) I've tried everything I can think of, but I can't get a nice helicorder output for Mathcad. There seems to be almost nothing on the Mathcad site or on the Internet about doing this. Any suggestions? Greg ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Plotting raw data with Mathcad From: Bobhelenmcclure@....... Date: Sat, 20 Aug 2005 23:44:15 EDT Hi Greg, I cannot help you with Mathcad, but I do have a utility program that plots WinQuake Type 4 files in heliplot format. Go to http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html and download "seismic_dataq.zip". There is a program in the ZIP called "WQFilter.exe" and its help file "WQFilterHlp.txt", which you could try if you wish. If you should want to be able to plot files longer in duration than 6 hours, let me know. It is possible to convert PSN Type 4 format files to WDQ format, and I have a program called "Heliplot.exe" which can plot any number of hours of WDQ format data. Bob McClure ~~~~~~Original Message~~~~~~~~ I've tried everything I can think of, but I can't get a nice helicorder output for Mathcad. There seems to be almost nothing on the Mathcad site or on the Internet about doing this. Any suggestions? Greg Hi Greg,

I cannot help you with Mathcad, but I do have a utility program that=20= plots
WinQuake Type 4 files in heliplot format. Go to

http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html

and download "seismic_dataq.zip". There is a program in the ZIP called
"WQFilter.exe" and its help file "WQFilterHlp.txt", which you could try if <= BR> you wish. If you should want to be able to plot files longer in duration tha= n
6 hours, let me know. It is possible to convert PSN Type 4 format files to W= DQ
format, and I have a program called "Heliplot.exe" which can plot any
number of hours of WDQ format data.

Bob McClure

~~~~~~Original Message~~~~~~~~
I've tried everything I can think of, but I can't get
a nice helicorder output for Mathcad. There seems to
be almost nothing on the Mathcad site or on the
Internet about doing this. Any suggestions? Greg Subject: Come on, I know there's a way to plot with Mathcad From: Mike Speed mike8s2@......... Date: Mon, 22 Aug 2005 11:08:55 -0700 (PDT) Look at: http://www.eas.slu.edu/People/STMorrissey/index.html Then: Then STM-8 Seis: Recent Quakes, Data How the heck do I do plots like that? Greg ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: BOB BARNS royb1@........... Date: Thu, 25 Aug 2005 10:24:43 -0400 Hi gang, I normally don't report books but this is a rare opportunity on a 2 volume set of great books. QUANTITATIVE SEISMOLOGY Theory & Methods AKI & RICHARDS Item number: 6974393718 ends Aug 31 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Simple broadband Seismometer From: "Dave Nelson" davefnelson@....... Date: Sat, 27 Aug 2005 23:38:51 -0700 I have been intrigued by the concept of using a liquid as the seismic = mass in a broadband instrument for some time. The original thought came = the idea that a damping plate was being moved through a liquid -- why = not move the liquid through the damping plate. I have also studied the = MET seismometer ( I operate a CME MET vertical seismometer in my home = system ) and have a moderate understanding of its principals and the = electrochemistry involved. To be brief I have been working for some months to develop a credible = instrument with no moving parts. After a lot of internet searches on the = related technologies and several learning experiences (read as total = failure) I came up wit a concept based on well known principals but with = some unique twists. The instrument uses water( with some off- the- shelf = additives) in a simple structure that resembles a large electrolytic = tiltmeter. The baseline of the first instrument was 1 meter. The key was = to have the fluid flow heavily overdamped to the point of creating a = hydraulic integrator . Damping is provided by a small conical seat = valve.The equivalent orifice when the valve is set for operation is less = than 1mm. Electrolytic transducers in the usual bridge arrangement are = at each end of a horizontal water column. The electronics consist of a = LTC1043 switched capacitor front end and two dual op amps -- that's ALL = ..The result is a very credible broadband seismometer (5 Hz to more than = 40 seconds -velocity). Some key points on performance: Noise from the electronics is negligible. Seismic background noise dominates. The day / night variation is clearly = visible Two identical instruments side by side see exactly the same signal in = absolute lock step. Microseism is clearly visible and can on occasion be the dominant = background. When filtered for short period the output exactly matches an HS-10-1 = background signal cycle by cycle. Telesesmic body and surface waves are recorded with sensitivity and = fidelity equal to my MET broadband and other broadband instruments = reported on the PSN network and other sources like the Berkeley = Seismological Laboratory. In one case a seismometer within 100 miles = matched nearly cycle by cycle for a teleseismic event. In short my test results are still a bit qualitative but I am convinced = (much to my surprise and pleasure) that the instrument is in family with = some very good broadband seismometers. This is a VERY simple device . Nothing moves but water.=20 The entire thing cost less than 50 bucks from the hardware store = plumbing department and the local electronics store (except for the = LTC1043). I have built four systems , Two 1 meter and Two 1/2 meter = baseline. Setup takes a little time to get the fluid level adjusted and = the instrument leveled. A test point provides the level adjustment = signal to a digital VM. Stabilization can take several hours, once = stable no attention is required as long as the base is stable. No = attempt has been made to create a tiltmeter, the electronics are AC = coupled with a 6.6 second (40 second period) time constant, slow / small = tilt drift is not a problem. I will be requesting permission to post events to PSN to back up what I = have claimed. I will also be writing a detailed description, with = pictures, to be available on request.=20 This is new stuff ,in operation about a month so development is still = underway. I have also been looking a vertical based on the same basic = concept,not sure about that yet but it looks possible. On a personal note, I am a retired electrical engineer with extensive = experience in instrument design , aerospace engineering and program = management -- this is not quack stuff. I believe I have something which could be of considerable interest to = the seismology community and am anxious to share what I have learned. I = prefer the telephone for detail discussion as I am not a good typist . I = am from the old school where a secretary did the typing so I am bit = slow on the keyboard. =20 I am looking forward to reading your comments and possibly telling me = how I reinvented the wheel. (If so, I haven't found that wheel). Dave Nelson (The one from LA -- not Australia)

I have been intrigued by the concept of = using a=20 liquid as the seismic mass in a broadband instrument for some time. The = original=20 thought came the idea that a damping plate was being moved through a = liquid --=20 why not move the liquid through the damping plate. I have also = studied the=20 MET seismometer ( I operate a CME MET vertical seismometer in = my home=20 system ) and have a moderate understanding of its principals and the=20 electrochemistry involved.

To be brief I have been working for = some months to=20 develop a credible instrument with no moving parts. After a lot of = internet=20 searches on the related technologies and several learning experiences = (read as=20 total failure) I came up wit a concept based on well known principals = but with=20 some unique twists. The instrument uses water( with some off- the- shelf = additives) in a simple structure that resembles a large electrolytic = tiltmeter.=20 The baseline of the first instrument was 1 meter. The key was to = have the=20 fluid flow heavily overdamped to the point of creating = a=20 hydraulic integrator . Damping is provided by a small conical = seat=20 valve.The equivalent orifice when the valve is set for operation = is less=20 than 1mm. Electrolytic transducers in the usual bridge=20 arrangement are at each end of a horizontal water column. The = electronics=20 consist of a LTC1043 switched capacitor front end and two dual op = amps --=20 that's ALL .The result is a very = credible=20 broadband seismometer (5 Hz to more than 40 seconds = -velocity).

Some key points on = performance:

Noise from the electronics is=20 negligible.

Seismic background noise dominates. The = day / night=20 variation is clearly visible

Two identical instruments side by side = see exactly=20 the same signal in absolute lock step.

Microseism is clearly visible and can = on occasion=20 be the dominant background.

When filtered for short period the = output exactly=20 matches an HS-10-1 background signal cycle by cycle.

Telesesmic body and surface waves = are=20 recorded with sensitivity and fidelity equal to my MET = broadband and other broadband instruments reported on the PSN network = and =20 other sources like the Berkeley Seismological Laboratory. In one = case a=20 seismometer within 100 miles matched nearly cycle by cycle for a = teleseismic=20 event.

In short my test results are still a = bit=20 qualitative but I am convinced (much to my surprise and pleasure) that = the=20 instrument is in family with some very good broadband = seismometers.

This is a VERY simple device . Nothing = moves but=20 water.

The entire thing cost less than 50 = bucks from=20 the hardware store plumbing department and the local electronics store = (except=20 for the LTC1043). I have built four systems , Two 1 meter and Two 1/2 = meter=20 baseline. Setup takes a little time to get the fluid level = adjusted and=20 the instrument leveled. A test point provides the level adjustment = signal to a=20 digital VM. Stabilization can take several hours, once stable = no=20 attention is required as long as the base is stable. No attempt has been = made to=20 create a tiltmeter, the electronics are AC coupled with a 6.6 = second (40=20 second period) time constant, slow / small tilt drift = is not a=20 problem.

I will be requesting permission to post = events to=20 PSN to back up what I have claimed. I will also be writing a=20 detailed description, with pictures, to be available on = request.=20

This is new stuff ,in operation about a = month so=20 development is still underway. I have also been looking a vertical = based on=20 the same basic concept,not sure about that yet but it looks=20 possible.

On a personal note, I am a = retired=20 electrical engineer with extensive experience in instrument design , = aerospace=20 engineering and program management -- this is not quack = stuff.

I believe I have something which could = be of=20 considerable interest to the seismology community and am anxious to = share what I=20 have learned. I prefer the telephone for detail discussion as I am not a = good=20 typist . I am from the old school where a secretary did the typing=20 so I am bit slow on the keyboard.

I am looking forward to reading your = comments and=20 possibly telling me how I reinvented the wheel. (If so, I haven't found = that=20 wheel).

Dave Nelson

(The one from LA -- not=20 Australia)

Subject: RE: Simple broadband Seismometer From: "Randy Kimball" randy.kimball@........... Date: Sun, 28 Aug 2005 08:34:56 -0500 Dave, 10-4 on the typing... I type well but don't spell worth a hoot... and I don't slow down and type well so what good is typing well in my case? I'm very interested, I too have thought of water as a sensor media many nights as I fall asleep (that's when I figure things out). Always seeks level, is responsive, is natures seismo sensor already,... watch for ripples and see everything. I'm also interested in magentic repulsion. .. back to water. .. for the moment. I'm very busy at the moment rerovating one of our rent houses. ..... enough said on that subject, I'm sure. .... B U T !!! .... Please, send me pictures of the water sensor. I'm having trouble wrapping myself around the concept from your discription and my lack of concentration at the moment. A picture is worth ten thousand words is some cases. My mind keeps thinking on two concepts with water. One, ....like one of those levels to check foundation shift. You have a cylinder with water in it and level marks. Then you have a hose running some distance away to another cylinder identical to the first, and another... so on. Then they add water and check the level in each cylinder to see where the water found level at what mark. So. this means you have a good sized or selected size reservor of a length and narrow width to test for tilt without the ripple effect. Well, this basic concept means that two containers some distance away with a sensor in one will sense the slightest tilt of the crust in that dirrection, with the size of the hose being the dampener... there are a few problems.. like delayed action. I'm sure the size/shape of the containers and length/distance/diamenter of the tubing or pipe between the containers could be used to work out the response. Distances between containers of sets could be used to select frequency responses per wave lenght of crust ripple. Compas direction could be selected to directions of special interesting seismic activities. ... Two. .....water ripples should be a perfect source to receive feed back of all movement in any low frequency. Something tells me you are using these concepts... please!!! .....kick back more information. ! ! ! My e-address is randy.kimball@........... ... my web site is at whazitfun.com thank you for your time, -randy- -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Dave Nelson Sent: Sunday, August 28, 2005 1:39 AM To: PSN-L@.............. Subject: Simple broadband Seismometer I have been intrigued by the concept of using a liquid as the seismic mass in a broadband instrument for some time. The original thought came the idea that a damping plate was being moved through a liquid -- why not move the liquid through the damping plate. I have also studied the MET seismometer ( I operate a CME MET vertical seismometer in my home system ) and have a moderate understanding of its principals and the electrochemistry involved. ======= clip clip to save space ============= This is new stuff ,in operation about a month so development is still underway. I have also been looking a vertical based on the same basic concept,not sure about that yet but it looks possible. On a personal note, I am a retired electrical engineer with extensive experience in instrument design , aerospace engineering and program management -- this is not quack stuff. I believe I have something which could be of considerable interest to the seismology community and am anxious to share what I have learned. I prefer the telephone for detail discussion as I am not a good typist . I am from the old school where a secretary did the typing so I am bit slow on the keyboard. I am looking forward to reading your comments and possibly telling me how I reinvented the wheel. (If so, I haven't found that wheel). Dave Nelson (The one from LA -- not Australia)

Dave,

10-4=20 on the typing... I type well but don't spell worth a hoot... = and I=20 don't slow down and type well so what good is typing well in my=20 case?

I'm=20 very interested, I too have thought of water as a sensor media many = nights as I=20 fall asleep (that's when I figure things out). Always seeks = level, is=20 responsive, is natures seismo sensor already,... watch for ripples and = see=20 everything. I'm also interested in magentic repulsion. .. = back to=20 water. .. for the moment.

I'm=20 very busy at the moment rerovating one of our rent houses. ..... enough = said on=20 that subject, I'm sure. .... B U T !!! ....

Please, send me pictures of the water = sensor. I'm=20 having trouble wrapping myself around the concept from your discription = and my=20 lack of concentration at the moment. A picture is worth ten = thousand words=20 is some cases.

My=20 mind keeps thinking on two concepts with water. One, ....like one = of those=20 levels to check foundation shift. You have a cylinder with water in it = and level=20 marks. Then you have a hose running some distance away to another = cylinder=20 identical to the first, and another... so on. Then they add water = and=20 check the level in each cylinder to see where the water found level at = what=20 mark. So. this means you have a good sized or selected size = reservor of a=20 length and narrow width to test for tilt without the ripple effect. = Well, this=20 basic concept means that two containers some distance away with a sensor = in one=20 will sense the slightest tilt of the crust in that dirrection, with the = size of=20 the hose being the dampener... there are a few problems.. like delayed=20 action. I'm sure the size/shape of the containers and=20 length/distance/diamenter of the tubing or pipe between the containers = could be=20 used to work out the response. Distances between containers of = sets could=20 be used to select frequency responses per wave lenght of crust=20 ripple. Compas direction could be selected = to directions of=20 special interesting seismic activities. ... Two. = ......water=20 ripples should be a perfect source to receive feed back of all movement = in any=20 low frequency.

Something tells me you are using these = concepts...=20 please!!! .....kick back more information. ! ! ! =

My=20 e-address is randy.kimball@........... = .... my web=20 site is at whazitfun.com

thank=20 you for your time,

-randy-

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Dave=20 Nelson
Sent: Sunday, August 28, 2005 1:39 AM
To:=20 PSN-L@..............
Subject: Simple broadband=20 Seismometer

I have been intrigued by the concept = of using a=20 liquid as the seismic mass in a broadband instrument for some time. = The=20 original thought came the idea that a damping plate was being moved = through a=20 liquid -- why not move the liquid through the damping plate. I = have also=20 studied the MET seismometer ( I operate a CME MET=20 vertical seismometer in my home system ) and have a moderate=20 understanding of its principals and the electrochemistry=20 involved.

=3D=3D=3D=3D=3D=3D=3D clip clip=20 to save space = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

This is new stuff ,in operation about = a month so=20 development is still underway. I have also been looking a = vertical based=20 on the same basic concept,not sure about that yet but it looks=20 possible.

On a personal note, I am = a retired=20 electrical engineer with extensive experience in instrument design , = aerospace=20 engineering and program management -- this is not quack = stuff.

I believe I have something which = could be of=20 considerable interest to the seismology community and am anxious to = share what=20 I have learned. I prefer the telephone for detail discussion as I am = not a=20 good typist . I am from the old school where a secretary did the = typing=20 so I am bit slow on the keyboard.

I am looking forward to reading your = comments and=20 possibly telling me how I reinvented the wheel. (If so, I haven't = found that=20 wheel).

Dave Nelson

(The one from LA -- not=20 Australia)

Subject: Re: Simple broadband Seismometer From: SW6079@....... Date: Sun, 28 Aug 2005 14:02:31 EDT Fascinating!! I imagine this idea may have occurred to someone before, but I certainly think it is original. Wish I'd thought of it! Best regards, Mike. Fascinating!! I imagine this idea m= ay have occurred to someone before, but I certainly think it is original.&nb= sp; Wish I'd thought of it! Best regards, Mike. Subject: Re: Simple broadband Seismometer From: meredith lamb paleoartifact@......... Date: Sun, 28 Aug 2005 14:00:00 -0600 WOW! Congratulations Dave! Amazing perserverance and effort went into this! On the surface; it sounds like this specific MET, it could well make all th= e=20 various designs of older horizontal mechanisms and sensors rather obsolete.= =20 It seems that the LTC1043 is more available in european/asia areas. Would b= e=20 interested in any possible U.S.A., distributors (and rough price)...if anyone knows of such. The item= =20 can be bought from Linear, but, they have a $250.00 minimum order charge.=20 Meredith Lamb On 8/28/05, Dave Nelson wrote: >=20 > I have been intrigued by the concept of using a liquid as the seismic mas= s=20 > in a broadband instrument for some time. The original thought came the id= ea=20 > that a damping plate was being moved through a liquid -- why not move the= =20 > liquid through the damping plate. I have also studied the MET seismometer= (=20 > I operate a CME MET vertical seismometer in my home system ) and have a= =20 > moderate understanding of its principals and the electrochemistry involve= d. > =20 clip.... WOW! Congratulations Dave! Amazing perserverance and effort wen= t into this!

On the surface; it sounds like this specific MET, it could well make all the various designs of older horizontal mechanisms and sensors rather obsolete.

It seems that the LTC1043 is more available in european/asia areas. W= ould be interested in any possible
U.S.A., distributors (and rough price)...if anyone knows of such. The= item can be bought from Linear, but, they
have a $250.00 minimum order charge.

Meredith Lamb

On 8/28/05, Dave Nelson <davefnelson@cox= ..net> wrote:

I have been intrigued by the concept o= f using a=20 liquid as the seismic mass in a broadband instrument for some time. The ori= ginal=20 thought came the idea that a damping plate was being moved through a liquid= --=20 why not move the liquid through the damping plate. I have also studie= d the=20 MET seismometer ( I operate a CME MET vertical seismometer in my = home=20 system ) and have a moderate understanding of its principals and the=20 electrochemistry involved.

= clip....
Subject: Re: Simple broadband Seismometer From: ChrisAtUpw@....... Date: Sun, 28 Aug 2005 21:27:08 EDT In a message dated 28/08/05, paleoartifact@......... writes: > Subj:Re: Simple broadband Seismometer > From: paleoartifact@......... (meredith lamb) > > Congratulations Dave! Amazing perseverance and effort went into this! > > On the surface; it sounds like this specific MET, it could well make all the > various designs of older horizontal mechanisms and sensors rather obsolete. > > It seems that the LTC1043 is more available in european/asia areas. Would > be interested in any possible U.S.A., distributors (and rough price) See www.digikey.com LTC1043CN-ND 18 pin DIP at US $5.13 Jeff Witt has a good bridge circuit using the LTC1043. See www.linear.com Application Note AN87 p87 While you can get Platinum wire and foil and also gold for making electrodes, they are expensive. Have you tried making the electrodes out of graphite? You can get single crystal graphite sheet. The central electrode rods from dry batteries are another convenient source. Battery electrodes usually come with a crimped brass cap. You can get silver and copper metallic paints to make a bond with graphite sheet. You can also use conical electrodes. Needle valves can give very non linear flow characteristics with differing flow rates. A more linear variable restriction may be obtained by squeezing flexible tubing (silicone rubber?) in between two flat strips of metal or plywood. I have used this to provide very tiny leak rates by putting a wire down the centre of the tube before it is clamped. You could also use thin nylon rod or monofilament to give a non conducting core. The fluid sees two tiny triangular tubes between the sides of the wire and the two tube surfaces. Nicolas d'Oreye http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-10172003-155611/ describes the flow and period calculations fairly fully in his thesis, although he applies it to a precision water tiltmeter. It is in French, so you may need http://babelfish.altavista.com/ On the subject of reducing the effects of surface tension, it should be possible to fit a very thin rubber membrane over the ends of the tube when using a capacitative detector --> no free surface. This would certainly be worth trying. I prefer capacitative sensing for measuring the height of water columns. The dielectric constant of water is about 80. Oil is usually about 2. This enables you to use high purity water which greatly reduces corrosion problems. You can use marine varnish to protect metal surfaces. > On 8/28/05, Dave Nelson <davefnelson@.......> wrote: > >> I have been intrigued by the concept of using a liquid as the seismic >> mass in a broadband instrument for some time. The original thought came the >> idea that a damping plate was being moved through a liquid -- why not move the >> liquid through the damping plate. I have also studied the MET seismometer (I >> operate a CME MET vertical seismometer in my home system) and have a >> moderate understanding of its principals and the electrochemistry involved. > I prefer the telephone for detail discussion as I am not a good typist. I > am from the old school where a secretary did the typing so I am bit slow on > I will let you into two secrets! You can get programs to teach you to type! It took me about a week to get reasonably proficient. You can also get programs which take a microphone input and give you a printed word output.... Regards, Chris Chapman In a message=20= dated 28/08/05, paleoartifact@......... writes:

Subj:Re: Simple broadban= d Seismometer
From: paleoartifact@......... (meredith lamb)

Congratulations Dave! Amazing perseverance and effort went into th= is!

On the surface; it sounds like this specific MET, it could well make all= the various designs of older horizontal mechanisms and sensors rather obsol= ete.

It seems that the LTC1043 is more available in european/asia areas. &nbs= p;Would be interested in any possible U.S.A., distributors (and rough price)=

      See www.digikey.com LTC1043CN-ND 18 pin DIP at US $5.13

   Jeff Witt has a good bridge circuit using the LTC1043= .. See www.linear.com Application Note= AN87 p87

      While you can get Platinum wire and= foil and also gold for making electrodes, they are expensive. Have you trie= d making the electrodes out of graphite? You can get single crystal graphite= sheet. The central electrode rods from dry batteries are another convenient= source. Battery electrodes usually come with a crimped brass cap. You can g= et silver and copper metallic paints to make a bond with graphite sheet. You= can also use conical electrodes.

   Needle valves can give very non linear flow character= istics with differing flow rates. A more linear variable restriction may be=20= obtained by squeezing flexible tubing (silicone rubber?) in between two flat= strips of metal or plywood.=20
      I have used this to provide very ti= ny leak rates by putting a wire down the centre of the tube before it is cla= mped. You could also use thin nylon rod or monofilament to give a non conduc= ting core. The fluid sees two tiny triangular tubes between the sides of the= wire and the two tube surfaces.
=20
   Nicolas d'Oreye http://edoc.bib.u= cl.ac.be:81/ETD-db/collection/available/BelnUcetd-10172003-155611/ descr= ibes the flow and period calculations fairly fully in his thesis, although h= e applies it to a precision water tiltmeter. It is in French, so you may nee= d http://babelfish.altavista.com/

      On the subject of reducing the effe= cts of surface tension, it should be possible to fit a very thin rubber memb= rane over the ends of the tube when using a capacitative detector --> no=20= free surface. This would certainly be worth trying.

      I prefer capacitative sensing for m= easuring the height of water columns. The dielectric constant of water is ab= out 80. Oil is usually about 2. This enables you to use high purity water wh= ich greatly reduces corrosion problems. You can use marine varnish to protec= t metal surfaces.=20

On 8/28/05, Dave Nelson<= /B> <davefnelson@.......> w= rote:
I have been intrigued by th= e concept of using a liquid as the seismic mass in a broadband instrument fo= r some time. The original thought came the idea that a damping plate was bei= ng moved through a liquid -- why not move the liquid through the damping pla= te. I have also studied the MET seismometer (I operate a CME MET vertical se= ismometer in my home system) and have a moderate understanding of its princi= pals and the electrochemistry involved.

I prefer the teleph= one for detail discussion as I am not a good typist. I am from the old schoo= l where a secretary did the typing so I am bit slow on the keyboard.

      I will let you into two secrets! Yo= u can get programs to teach you to type! It took me about a week to get reas= onably proficient.
      You can also get programs which tak= e a microphone input and give you a printed word output....=20

      Regards,

      Chris Chapman Subject: Re: Simple broadband Seismometer From: Mike Price mprice@........ Date: Sun, 28 Aug 2005 18:34:56 -0700 $5.13 unit price at Digikey. They have 2870 in stock. Mike Price meredith lamb wrote: > WOW! Congratulations Dave! Amazing perserverance and effort went > into this! > > On the surface; it sounds like this specific MET, it could well make > all the various designs of older horizontal mechanisms and sensors > rather obsolete. > > It seems that the LTC1043 is more available in european/asia areas. > Would be interested in any possible > U.S.A., distributors (and rough price)...if anyone knows of such. The > item can be bought from Linear, but, they > have a $250.00 minimum order charge. > > Meredith Lamb > > > On 8/28/05, *Dave Nelson* > wrote: > > I have been intrigued by the concept of using a liquid as the > seismic mass in a broadband instrument for some time. The original > thought came the idea that a damping plate was being moved through > a liquid -- why not move the liquid through the damping plate. I > have also studied the MET seismometer ( I operate a CME MET > vertical seismometer in my home system ) and have a moderate > understanding of its principals and the electrochemistry involved. > > > clip.... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Simple broadband Seismometer From: "John D Nelson" jnelson@................. Date: Mon, 29 Aug 2005 08:57:33 -0500 How exactly is the LTC1043 used? Are we sensing capacitance change in distance or resistance change in fluid depth? I need more information. The mercury tiltlevel sensor is well known but it works because mercury is a cohesive, not an adhesive liquid. Help me out here, this sounds really interesting. =20 John Nelson =20 ________________________________ From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Sunday, August 28, 2005 8:27 PM To: psn-l@.............. Subject: Re: Simple broadband Seismometer =20 In a message dated 28/08/05, paleoartifact@......... writes:=20 Subj:Re: Simple broadband Seismometer=20 From: paleoartifact@......... (meredith lamb)=20 Congratulations Dave! Amazing perseverance and effort went into this!=20 On the surface; it sounds like this specific MET, it could well make all the various designs of older horizontal mechanisms and sensors rather obsolete. =20 It seems that the LTC1043 is more available in european/asia areas. Would be interested in any possible U.S.A., distributors (and rough price) See www.digikey.com LTC1043CN-ND 18 pin DIP at US $5.13=20 Jeff Witt has a good bridge circuit using the LTC1043. See www.linear.com Application Note AN87 p87=20 While you can get Platinum wire and foil and also gold for making electrodes, they are expensive. Have you tried making the electrodes out of graphite? You can get single crystal graphite sheet. The central electrode rods from dry batteries are another convenient source. Battery electrodes usually come with a crimped brass cap. You can get silver and copper metallic paints to make a bond with graphite sheet. You can also use conical electrodes.=20 Needle valves can give very non linear flow characteristics with differing flow rates. A more linear variable restriction may be obtained by squeezing flexible tubing (silicone rubber?) in between two flat strips of metal or plywood.=20 I have used this to provide very tiny leak rates by putting a wire down the centre of the tube before it is clamped. You could also use thin nylon rod or monofilament to give a non conducting core. The fluid sees two tiny triangular tubes between the sides of the wire and the two tube surfaces.=20 Nicolas d'Oreye http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-10172 003-155611/ describes the flow and period calculations fairly fully in his thesis, although he applies it to a precision water tiltmeter. It is in French, so you may need http://babelfish.altavista.com/ =20 On the subject of reducing the effects of surface tension, it should be possible to fit a very thin rubber membrane over the ends of the tube when using a capacitative detector --> no free surface. This would certainly be worth trying.=20 I prefer capacitative sensing for measuring the height of water columns. The dielectric constant of water is about 80. Oil is usually about 2. This enables you to use high purity water which greatly reduces corrosion problems. You can use marine varnish to protect metal surfaces.=20 On 8/28/05, Dave Nelson wrote:=20 I have been intrigued by the concept of using a liquid as the seismic mass in a broadband instrument for some time. The original thought came the idea that a damping plate was being moved through a liquid -- why not move the liquid through the damping plate. I have also studied the MET seismometer (I operate a CME MET vertical seismometer in my home system) and have a moderate understanding of its principals and the electrochemistry involved. I prefer the telephone for detail discussion as I am not a good typist. I am from the old school where a secretary did the typing so I am bit slow on the keyboard. I will let you into two secrets! You can get programs to teach you to type! It took me about a week to get reasonably proficient.=20 You can also get programs which take a microphone input and give you a printed word output....=20 Regards,=20 Chris Chapman

How exactly is the LTC1043 used? = Are we sensing capacitance change in distance or resistance change in fluid = depth? I need more information. The mercury tiltlevel sensor is well known = but it works because mercury is a cohesive, not an adhesive liquid. Help me out = here, this sounds really interesting.

John = Nelson

From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of = ChrisAtUpw@.......
Sent: Sunday, August 28, = 2005 8:27 PM
To: = psn-l@..............
Subject: Re: Simple = broadband Seismometer

In a message dated 28/08/05, paleoartifact@......... = writes:

Subj:Re: Simple = broadband Seismometer
From:    paleoartifact@......... (meredith lamb)

Congratulations Dave! Amazing perseverance and effort went into = this!

On the surface; it sounds like this specific MET, it could well make all = the various designs of older horizontal mechanisms and sensors rather = obsolete.

It seems that the LTC1043 is more available in european/asia areas. = Would be interested in any possible U.S.A., distributors (and rough price)

      See = www.digikey.com LTC1043CN-ND 18 pin DIP at US $5.13

   Jeff Witt has a good bridge circuit using the LTC1043. = See www.linear.com Application Note AN87 = p87

      While you can get Platinum wire and = foil and also gold for making electrodes, they are expensive. Have you tried = making the electrodes out of graphite? You can get single crystal graphite = sheet. The central electrode rods from dry batteries are another convenient source. = Battery electrodes usually come with a crimped = brass cap. You can get silver and copper metallic paints to make a bond with = graphite sheet. You can also use conical electrodes.

   Needle valves can give very non linear flow = characteristics with differing flow rates. A more linear variable restriction may be = obtained by squeezing flexible tubing (silicone rubber?) in between two flat = strips of metal or plywood.
      I have used this to provide very = tiny leak rates by putting a wire down the centre of the tube before it is = clamped. You could also use thin nylon rod or monofilament to give a non conducting = core. The fluid sees two tiny triangular tubes between the sides of the wire = and the two tube surfaces.

   Nicolas d'Oreye http://edoc.bib.ucl.ac.be:81/ETD-db/collection/availa= ble/BelnUcetd-10172003-155611/ describes the flow and period calculations fairly fully in his thesis, = although he applies it to a precision water tiltmeter. It is in French, so you = may need http://babelfish.altavista.com/

      On the subject of reducing the = effects of surface tension, it should be possible to fit a very thin rubber = membrane over the ends of the tube when using a capacitative detector --> no free = surface. This would certainly be worth trying.

      I prefer capacitative sensing for = measuring the height of water columns. The dielectric constant of water is about = 80. Oil is usually about 2. This enables you to use high purity water which = greatly reduces corrosion problems. You can use marine varnish to protect metal surfaces.

On 8/28/05, = Dave Nelson <davefnelson@.......> wrote: =

I have been = intrigued by the concept of using a liquid as the seismic mass in a broadband = instrument for some time. The original thought came the idea that a damping plate was = being moved through a liquid -- why not move the liquid through the damping = plate. I have also studied the MET seismometer (I operate a CME MET vertical = seismometer in my home system) and have a moderate understanding of its principals = and the electrochemistry involved.

I prefer the = telephone for detail discussion as I am not a good typist. I am from the old = school where a secretary did the typing so I am bit slow on the = keyboard.

      I will let you into two secrets! You = can get programs to teach you to type! It took me about a week to get = reasonably proficient.
      You can also get programs which take = a microphone input and give you a printed word output....

      Regards,

      Chris = Chapman

Subject: water seismometers From: "Dave Nelson" davefnelson@....... Date: Mon, 29 Aug 2005 09:17:13 -0700 I have been reading the various comments on transducers for water based = seismometers. I initially planned to use a capacitive sensor taking advantage of the = high dielectric constant of water. I am very familiar with precision = capacitive bridge circuits such as those used in the MKS capacitance = manometer and other high sensitivity pressure sensors. In fact when I = started this investigation I had tried the MKS manometer as the sensor = to sense the motion of the water .=20 The problem is that these sensors must work in a gas not a liquid. I = have also built capacitive sensors for use in water. The water must be = very pure or the conductivity becomes a contaminating factor in the = bridge causing a phase shift .The water/oil interface seems like a good = configuration but it has problems if you want to have some portability. = You have to fill the thing where you want to use it. The coaxial = configuration I currently have in my sensor was originally intended to = be capacitive but the conductivity of even distilled water was an issue = particularly if you add something to keep the water from "sticking " to = the electrode. The use of detergents to eliminate some of the surface = tension effects also increased the water conductivity. I finally said if = you can't beat it -- exploit it so, I made based my system on variable = contact area in a conductive fluid in a vertical coaxial configuration. = The water is mixed with dishwasher sheeting agent like made by "Cascade" = in a 100 to 1 ratio. This give the right conductivity and make the = meniscus ride up and down on the brass pipe electrode surfaces without = sticking . The meniscus stays at a fixed contact angle . I have also = used much lower concentrations of various detergents and very small = amount of salt to add the ions needed for conductivity. I built a test = cell to evaluate different mixtures. =20 The transducer is of course the core of the instrument -- I have tried a = lot of things and do not claim to have found the optimum but it does = work pretty well and is easy to deal with. I can pick the whole = instrument up ,not worry about mixing different fluids move it without = any concern about handling it an any special way. It make some time to = restabilize but in a day or so it will be back to normal operation. = Bubbles are a big problem on initial fill and following rough handling = but they go away .=20 I think there is room for a lot of work in this area ,so keep the = discussion going. Regarding the LTC 1043 -- I buy them on-line from Linear in lots of 10 = for about $3.50 each. No minimum order. I have had no problem getting = them. The can be used in many different configurations including some = very good capacitive bridge circuits. It is truly a universal building = block for instrumentation systems. I first discovered it in a = capacitance pressure sensor made by Modus. Regarding pressure sensors and water based seismometers . I tried lots = of configurations with some limited success but the usual problem was = noise from atmospheric pressure changes . Even if the system is = completely closed the tubing or pipe will be compressed by the pressure = change. when you are working with pressure changes of 10e-6 torr in a = 1000 torr atmosphere the noise can be overwhelming no matter how you try = it isolate it. I gave it up after trying many different configurations. = For those interested in infrasound some of the sensors I investigated = would be ideal. Dave Nelson
I have been reading the various = comments on=20 transducers for water based seismometers.

I initially planned to use a = capacitive=20 sensor taking advantage of the high dielectric constant of water. I am = very=20 familiar with precision capacitive bridge circuits such as those used in = the MKS=20 capacitance manometer and other high sensitivity pressure sensors. In = fact when=20 I started this investigation I had tried the MKS manometer as the sensor = to=20 sense the motion of the water .

The problem is that these sensors = must work=20 in a gas not a liquid. I have also built capacitive sensors for use in = water.=20 The water must be very pure or the conductivity becomes a contaminating = factor=20 in the bridge causing a phase shift .The water/oil interface seems like = a good=20 configuration but it has problems if you want to have some portability. = You have=20 to fill the thing where you want to use it. The coaxial = configuration I=20 currently have in my sensor was originally intended to be capacitive but = the=20 conductivity of even distilled water was an issue particularly if you = add=20 something to keep the water from "sticking " to the electrode. The use = of=20 detergents to eliminate some of the surface tension effects also = increased the=20 water conductivity. I finally said if you can't beat it -- exploit it = so, I made=20 based my system on variable contact area in a conductive fluid in a=20 vertical coaxial configuration. The water is mixed with dishwasher = sheeting=20 agent like made by "Cascade" in a 100 to 1 ratio. This give the right=20 conductivity and make the meniscus ride up and down on the brass pipe=20 electrode surfaces without sticking . The meniscus stays at a = fixed=20 contact angle . I have also used much lower concentrations of various = detergents=20 and very small amount of salt to add the ions needed for = conductivity.=20 I built a test cell to evaluate different mixtures.=20             &= nbsp;           &n= bsp;    =20

The transducer is of course the core of = the=20 instrument -- I have tried a lot of things and do not claim to have = found the=20 optimum but it does work pretty well and is easy to deal with. I = can pick=20 the whole instrument up ,not worry about mixing different fluids move it = without=20 any concern about handling it an any special way. It make some time to=20 restabilize but in a day or so it will be back to normal operation. = Bubbles are=20 a big problem on initial fill and following rough handling but they go = away .=20

I think there is room for a lot of work = in this=20 area ,so keep the discussion going.

Regarding the LTC 1043 -- I buy = them on-line=20 from Linear in lots of 10 for about $3.50 each. No minimum = order. I=20 have had no problem getting them. The can be used in many different=20 configurations including some very good capacitive bridge circuits. It = is truly=20 a universal building block for instrumentation systems. I first = discovered it in=20 a capacitance pressure sensor made by Modus.

Regarding pressure sensors and = water based=20 seismometers . I tried lots of configurations with some limited success = but the=20 usual problem was noise from atmospheric pressure changes . Even if the = system=20 is completely closed the tubing or pipe will be compressed by the = pressure=20 change. when you are working with pressure changes of 10e-6 torr in a = 1000 torr=20 atmosphere the noise can be overwhelming no matter how you try = it=20 isolate it. I gave it up after trying many different configurations. For = those=20 interested in infrasound some of the sensors I investigated would be=20 ideal.

Dave Nelson

Subject: Re: water seismometers From: ChrisAtUpw@....... Date: Mon, 29 Aug 2005 20:48:05 EDT In a message dated 29/08/05, davefnelson@....... writes: > I initially planned to use a capacitative sensor taking advantage of the > high dielectric constant of water. I am very familiar with precision > capacitative bridge circuits such as those used in the MKS capacitance manometer and > other high sensitivity pressure sensors. > > The problem is that these sensors must work in a gas not a liquid. I have > also built capacitative sensors for use in water. The water must be very pure > or the conductivity becomes a contaminating factor in the bridge causing a > phase shift. Can you operate an MKS sensor in oil? It would have a different sensitivity. You need to boil distilled water to get the air out and then cool it in a sealed container. If you leave pure water open to air, it absorbs CO2 (as well as O2 and N2), which gives you very dilute carbonic acid. You fill the tiltmeter / seismometer etc and then either cover the ends with oil or seal in a Nitrogen atmosphere. The water/oil interface seems like a good configuration but it has problems if you > want to have some portability. You have to fill the thing where you want to > use it. You can get vacuum valves which fit water pipe sizes. These have a thick rubber diaphragm compression closure and O ring clamp fittings for the pipes. If you fit one in the centre of the apparatus, you can close off the middle and prevent flow to either end for handling. The coaxial configuration I currently have in my sensor was originally intended to be > capacitative but the conductivity of even distilled water was an issue > particularly if you add something to keep the water from "sticking" to the > electrode. The use of detergents to eliminate some of the surface tension effects > also increased the water conductivity. I finally said if you can't beat it -- > exploit it so, I made based my system on variable contact area in a > conductive fluid in a vertical coaxial configuration. The water is mixed with > dishwasher sheeting agent like made by "Cascade" in a 100 to 1 ratio. This gives the > right conductivity and makes the meniscus ride up and down on the brass pipe > electrode surfaces without sticking. The meniscus stays at a fixed contact > angle. I have also used much lower concentrations of various detergents and > very small amount of salt to add the ions needed for conductivity. I built a > test cell to evaluate different mixtures. Another capacitance method is to coat the metal surfaces with marine varnish to prevent conduction. It can be dusted with Aluminium or Titanium Oxide while wet. Alcohol is quite effective at reducing surface tension. In the traditional tiltmeter applications you have a larger diameter pot at either end of the horizontal tube, which increases the period, a horizontal disk electrode just below the water surface and a horizontal disk electrode either in free gas or submerged in oil just above the water surface. You may use 10 to 50 pF total. Due to the high dielectric constant of water, this arrangement is not too sensitive to changes in conduction. If you use oil with a dielectric constant of 2, you can allow a greater physical separation of the water surface from the bottom of the top electrode for a comparable capacity. Have a look at http://ntweb.mcn.org/gbush/Tiltmeter/tiltmeter%20Main.html Another method is to use the capacitance as part of a high stability RC oscillator and measure the change in frequency at both ends. This can give a linear position readout. Some frequency meters have a RS232 digital output which can be hooked up to your computer. I would advise against adding salt or any other halide to water to increase the conductivity. They are much too corrosive. Have you tried bicarbonate of soda? > The transducer is of course the core of the instrument -- I have tried a > lot of things and do not claim to have found the optimum but it does work > pretty well and is easy to deal with. I can pick the whole instrument up, not > worry about mixing different fluids move it without any concern about handling it > an any special way. It make some time to restabilize but in a day or so it > will be back to normal operation. Bubbles are a big problem on initial fill > and following rough handling but they go away. You can buy a water jet pump to provide a near vacuum for the initial fill. Even pumping out by connecting the suction end of a small paint spray compressor will considerably reduce the volume of any trapped air. > Regarding pressure sensors and water based seismometers. I tried lots of > configurations with some limited success but the usual problem was noise from > atmospheric pressure changes. Even if the system is completely closed the > tubing or pipe will be compressed by the pressure change. When you are working > with pressure changes of 10e-6 torr in a 1000 torr atmosphere the noise can be > overwhelming no matter how you try it isolate it. I gave it up after trying > many different configurations. For those interested in infrasound some of the > I am puzzled as to why you are seeing ANY signals due to atmospheric pressure / noise changes. The more usual arrangement is to provide a central inverted U tube half filled with oil and a differential pressure sensor at the top. The oil floats on the water and the sensor is only in contact with oil. If you have sealed end pots on the ends of the two arms but connect them together with a plastic tube, while the gas pressure may change with time and temperature, it is the same for both arms and the differential sensor will not see it. It is an advantage to use silicone fluid, since it is inert. You can use 'transformer' oil. It comes in several viscosities. Lubricating oil may have a lot of quite nasty additives and is best avoided. You can use a large piezo sounder disk as the sensor if you are only interested in periods up to about 5 to 10 seconds. These also make quite good infrasound sensors, but they need a very stable temperature environment. Another type of diaphragm sensor may be made by sticking discs of thin Permalloy or similar onto the centre of a circular stretched mylar membrane, with two coils in ferrite transformer cups on either side. The coils are connected up as a LR relaxation oscillator and you detect the Mark/Space variation as the discs move toward or away from either coil. These are used to measure very small air pressure changes as a glider gains or looses height. Regards, Chris Chapman In a message=20= dated 29/08/05, davefnelson@....... writes:

I initially planned to use= a capacitative sensor taking advantage of the high dielectric constant of w= ater. I am very familiar with precision capacitative bridge circuits such as= those used in the MKS capacitance manometer and other high sensitivity pres= sure sensors.
=20
The problem is that these sensors must work in a gas not a liquid. I ha= ve also built capacitative sensors for use in water. The water must be very=20= pure or the conductivity becomes a contaminating factor in the bridge causin= g a phase shift.

      Can you operate an MKS sensor in oi= l? It would have a different sensitivity.=20

   You need to boil distilled water to get the air out a= nd then cool it in a sealed container. If you leave pure water open to air,=20= it absorbs CO2 (as well as O2 and N2), which gives you very dilute carbonic=20= acid. You fill the tiltmeter / seismometer etc and then either cover the end= s with oil or seal in a Nitrogen atmosphere.=20

The water/oil interface seems like a good configuration but it has p= roblems if you
want to have some portab= ility. You have to fill the thing where you want to use it.

      You can get vacuum valves which=20= fit water pipe sizes. These have a thick rubber diaphragm compression closur= e and O ring clamp fittings for the pipes. If you fit one in the centre of t= he apparatus, you can close off the middle and prevent flow to either end fo= r handling.
=20
The coaxial configuration I currently have in my sensor was originally=20= intended to be
capacitative but the con= ductivity of even distilled water was an issue particularly if you add somet= hing to keep the water from "sticking" to the electrode. The use of detergen= ts to eliminate some of the surface tension effects also increased the water= conductivity. I finally said if you can't beat it -- exploit it so, I made=20= based my system on variable contact area in a conductive fluid in a vertical= coaxial configuration. The water is mixed with dishwasher sheeting agent li= ke made by "Cascade" in a 100 to 1 ratio. This gives the right conductivity=20= and makes the meniscus ride up and down on the brass pipe electrode surfaces= without sticking. The meniscus stays at a fixed contact angle. I have also=20= used much lower concentrations of various detergents and very small amount o= f salt to add the ions needed for conductivity. I built a test cell to evalu= ate different mixtures.

      Another capacitance method is to= coat the metal surfaces with marine varnish to prevent conduction. It can b= e dusted with Aluminium or Titanium Oxide while wet. Alcohol is quite=20= effective at reducing surface tension.
      In the traditional tiltmeter applic= ations you have a larger diameter pot at either end of the horizontal tube,=20= which increases the period, a horizontal disk electrode just below the water= surface and a horizontal disk electrode either in free gas or submerged in=20= oil just above the water surface. You may use 10 to 50 pF total. Due to the=20= high dielectric constant of water, this arrangement is not too sensitive to=20= changes in conduction. If you use oil with a dielectric constant of 2, you c= an allow a greater physical separation of the water surface from the bottom=20= of the top electrode for a comparable capacity.
      Have a look at http://ntweb.mcn.org= /gbush/Tiltmeter/tiltmeter%20Main.html
      Another method is to use the capaci= tance as part of a high stability RC oscillator and measure the change in fr= equency at both ends. This can give a linear position readout. Some frequenc= y meters have a RS232 digital output which can be hooked up to your computer= .
      I would advise against adding salt=20= or any other halide to water to increase the conductivity. They are much too= corrosive. Have you tried bicarbonate of soda?=20
            = ;            &nb= sp;
The transducer is of cou= rse the core of the instrument -- I have tried a lot of things and do not cl= aim to have found the optimum but it does work pretty well and is easy to de= al with. I can pick the whole instrument up, not worry about mixing differen= t fluids move it without any concern about handling it an any special way. I= t make some time to restabilize but in a day or so it will be back to normal= operation. Bubbles are a big problem on initial fill and following rough ha= ndling but they go away.

      You can buy a water jet pump to pro= vide a near vacuum for the initial fill. Even pumping out by connecting the=20= suction end of a small paint spray compressor will considerably reduce the v= olume of any trapped air.=20

Regarding pressure sensors=20= and water based seismometers. I tried lots of configurations with some limit= ed success but the usual problem was noise from atmospheric pressure changes= .. Even if the system is completely closed the tubing or pipe will be compres= sed by the pressure change. When you are working with pressure changes of 10= e-6 torr in a 1000 torr atmosphere the noise can be overwhelming no matter h= ow you try it isolate it. I gave it up after trying many different configura= tions. For those interested in infrasound some of the sensors I investigated= would be ideal.


      I am puzzled as to why you are seei= ng ANY signals due to atmospheric pressure / noise changes.

      The more usual arrangement is to pr= ovide a central inverted U tube half filled with oil and a differential p= ressure sensor at the top. The oil floats on the water and the sensor is= only in contact with oil. If you have sealed end pots on the ends of the tw= o arms but connect them together with a plastic tube, while the gas pressure= may change with time and temperature, it is the same for both arms and the=20= differential sensor will not see it. It is an advantage to use silicone flui= d, since it is inert. You can use 'transformer' oil. It comes in several vis= cosities. Lubricating oil may have a lot of quite nasty additives and is bes= t avoided. You can use a large piezo sounder disk as the sensor if you are o= nly interested in periods up to about 5 to 10 seconds. These also make quite= good infrasound sensors, but they need a very stable temperature environmen= t.
      Another type of diaphragm sensor ma= y be made by sticking discs of thin Permalloy or similar onto the centre of=20= a circular stretched mylar membrane, with two coils in ferrite transformer c= ups on either side. The coils are connected up as a LR relaxation oscillator= and you detect the Mark/Space variation as the discs move toward or away fr= om either coil. These are used to measure very small air pressure changes as= a glider gains or looses height.=20

      Regards,

      Chris Chapman Subject: Re: water seismometers From: Gordon Couger gcouger@.......... Date: Wed, 31 Aug 2005 03:36:04 -0500 Hi Chris, Two coats of Epoxy swimming pool paint will absorb about 2% moisture and works very well with capacitive sensor. I built a soil moisture senor that way that the condenser was part of the oscillator that determined the frequency. There are better ways. Gordon ChrisAtUpw@....... wrote: > In a message dated 29/08/05, davefnelson@....... writes: > >> I initially planned to use a capacitative sensor taking advantage of >> the high dielectric constant of water. I am very familiar with >> precision capacitative bridge circuits such as those used in the MKS >> capacitance manometer and other high sensitivity pressure sensors. >> >> The problem is that these sensors must work in a gas not a liquid. I >> have also built capacitative sensors for use in water. The water must >> be very pure or the conductivity becomes a contaminating factor in the >> bridge causing a phase shift. > > > > Can you operate an MKS sensor in oil? It would have a different > sensitivity. > > You need to boil distilled water to get the air out and then cool it > in a sealed container. If you leave pure water open to air, it absorbs > CO2 (as well as O2 and N2), which gives you very dilute carbonic acid. > You fill the tiltmeter / seismometer etc and then either cover the ends > with oil or seal in a Nitrogen atmosphere. > > The water/oil interface seems like a good configuration but it has > problems if you > >> want to have some portability. You have to fill the thing where you >> want to use it. > > > > You can get vacuum valves which fit water pipe sizes. These have a > thick rubber diaphragm compression closure and O ring clamp fittings for > the pipes. If you fit one in the centre of the apparatus, you can close > off the middle and prevent flow to either end for handling. > > The coaxial configuration I currently have in my sensor was originally > intended to be > >> capacitative but the conductivity of even distilled water was an issue >> particularly if you add something to keep the water from "sticking" to >> the electrode. The use of detergents to eliminate some of the surface >> tension effects also increased the water conductivity. I finally said >> if you can't beat it -- exploit it so, I made based my system on >> variable contact area in a conductive fluid in a vertical coaxial >> configuration. The water is mixed with dishwasher sheeting agent like >> made by "Cascade" in a 100 to 1 ratio. This gives the right >> conductivity and makes the meniscus ride up and down on the brass pipe >> electrode surfaces without sticking. The meniscus stays at a fixed >> contact angle. I have also used much lower concentrations of various >> detergents and very small amount of salt to add the ions needed for >> conductivity. I built a test cell to evaluate different mixtures. > > > > Another capacitance method is to coat the metal surfaces with > marine varnish to prevent conduction. It can be dusted with Aluminium or > Titanium Oxide while wet. Alcohol is quite effective at reducing > surface tension. > In the traditional tiltmeter applications you have a larger > diameter pot at either end of the horizontal tube, which increases the > period, a horizontal disk electrode just below the water surface and a > horizontal disk electrode either in free gas or submerged in oil just > above the water surface. You may use 10 to 50 pF total. Due to the high > dielectric constant of water, this arrangement is not too sensitive to > changes in conduction. If you use oil with a dielectric constant of 2, > you can allow a greater physical separation of the water surface from > the bottom of the top electrode for a comparable capacity. > Have a look at > http://ntweb.mcn.org/gbush/Tiltmeter/tiltmeter%20Main.html > Another method is to use the capacitance as part of a high > stability RC oscillator and measure the change in frequency at both > ends. This can give a linear position readout. Some frequency meters > have a RS232 digital output which can be hooked up to your computer. > I would advise against adding salt or any other halide to water to > increase the conductivity. They are much too corrosive. Have you tried > bicarbonate of soda? > > >> The transducer is of course the core of the instrument -- I have tried >> a lot of things and do not claim to have found the optimum but it does >> work pretty well and is easy to deal with. I can pick the whole >> instrument up, not worry about mixing different fluids move it without >> any concern about handling it an any special way. It make some time to >> restabilize but in a day or so it will be back to normal operation. >> Bubbles are a big problem on initial fill and following rough handling >> but they go away. > > > > You can buy a water jet pump to provide a near vacuum for the > initial fill. Even pumping out by connecting the suction end of a small > paint spray compressor will considerably reduce the volume of any > trapped air. > >> Regarding pressure sensors and water based seismometers. I tried lots >> of configurations with some limited success but the usual problem was >> noise from atmospheric pressure changes. Even if the system is >> completely closed the tubing or pipe will be compressed by the >> pressure change. When you are working with pressure changes of 10e-6 >> torr in a 1000 torr atmosphere the noise can be overwhelming no matter >> how you try it isolate it. I gave it up after trying many different >> configurations. For those interested in infrasound some of the sensors >> I investigated would be ideal. > > > > I am puzzled as to why you are seeing ANY signals due to > atmospheric pressure / noise changes. > > The more usual arrangement is to provide a central inverted U tube > half filled with oil and a /differential pressure sensor/ at the top. > The oil floats on the water and the sensor is only in contact with oil. > If you have sealed end pots on the ends of the two arms but connect them > together with a plastic tube, while the gas pressure may change with > time and temperature, it is the same for both arms and the differential > sensor will not see it. It is an advantage to use silicone fluid, since > it is inert. You can use 'transformer' oil. It comes in several > viscosities. Lubricating oil may have a lot of quite nasty additives and > is best avoided. You can use a large piezo sounder disk as the sensor if > you are only interested in periods up to about 5 to 10 seconds. These > also make quite good infrasound sensors, but they need a very stable > temperature environment. > Another type of diaphragm sensor may be made by sticking discs of > thin Permalloy or similar onto the centre of a circular stretched mylar > membrane, with two coils in ferrite transformer cups on either side. The > coils are connected up as a LR relaxation oscillator and you detect the > Mark/Space variation as the discs move toward or away from either coil. > These are used to measure very small air pressure changes as a glider > gains or looses height. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: capacitance to digital converter From: "Jack Ivey" ivey@.......... Date: Wed, 31 Aug 2005 09:09:57 -0400 Folks, I just stumbled across something a few people might find interesting, it might also be relevant to the water seismo discussion. Analog Devices has a capacitance to digital converter. Basically, you hook up your capacitive (position) sensor to an excitation output pin and a sense input pin, and the chip puts out a 24-bit digital output. They're claiming from 16 to 21 useful bits at a 10+ Hz rate. the '45, '46 are for floating sensors (single ended or differential) where you have=20 access to both sides of the capacitor, and the '47 is for a grounded differential sensor. http://www.analog.com/en/prod/0%2C2877%2CAD7745%2C00.html Hooking it up isn't completely trivial, it requires=20 knowledge of microprocessor communications (I2C). If it works out ok, the electronics for a non-feedback seismo might be reduced to this chip, an 8-pin microprocessor putting the data out on RS-232, and a few Rs and Cs. The part numbers are AD7745-AD7747. The AD7747 is not quite in=20 production yet). Jack __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: capacitance to digital converter From: "James Hannon" jmhannon@......... Date: Wed, 31 Aug 105 08:31:17 CDT I have been looking at these parts for a while and have some samples ordered. What I am planning to do is to interface the part to a DLP2232M http://www.dlpdesign.com/usb/2232m.shtml The DLP2232M will talk I2C and plug into a USB port. There is software avaliable to interface with the I2C data but one would have to write an application to log the data. The DLP2232M is also a dual serial port to USB and other various serial and parallel interfaces. Jim Hannon ---------- Original Message ---------------------------------- From: "Jack Ivey" Reply-To: psn-l@.............. Date: Wed, 31 Aug 2005 09:09:57 -0400 >Folks, >I just stumbled across something a few people might find interesting, >it might also be relevant to the water seismo discussion. >Analog Devices has a capacitance to digital converter. Basically, you >hook up your capacitive (position) sensor to an excitation output pin >and a sense input pin, and the chip puts out a 24-bit digital output. >They're claiming >from 16 to 21 useful bits at a 10+ Hz rate. the '45, '46 are for >floating sensors (single ended or differential) where you have >access to both sides of the capacitor, and the '47 is for a grounded >differential sensor. > >http://www.analog.com/en/prod/0%2C2877%2CAD7745%2C00.html > >Hooking it up isn't completely trivial, it requires >knowledge of microprocessor communications (I2C). If it works >out ok, the electronics for a non-feedback seismo might be reduced to >this chip, an 8-pin microprocessor putting the data out on >RS-232, and a few Rs and Cs. > >The part numbers are AD7745-AD7747. The AD7747 is not quite in >production yet). > >Jack > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > -- Jim Hannon http://www.fmtcs.com/web/jmhannon/ 42,11.90N,91,39.26W WB0TXL -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Simple broadband Seismometer From: ian ian@........... Date: Wed, 31 Aug 2005 21:44:53 +0100 I did a back-of-the-envelope calculation today for a 10 m long pipe, 15cm in diameter, half filled with liquid, sitting on 1 support at each end. When the pipe is tilted by 1 micro radian, the difference in loading between the posts is the equivalent of around 3 or 4 grams. Could this be approached by monitoring the loading on the supports? Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Simple broadband Seismometer From: ChrisAtUpw@....... Date: Thu, 1 Sep 2005 08:06:44 EDT In a message dated 31/08/05, ian@........... writes: > I did a back-of-the-envelope calculation today for a 10 m long pipe, > 15cm in diameter, half filled with liquid, sitting on 1 support at each > end. When the pipe is tilted by 1 micro radian, the difference in > loading between the posts is the equivalent of around 3 or 4 grams. > > Could this be approached by monitoring the loading on the supports? > > Ian Smith Hi Ian, The total water mass would be about 88.3 Kgm, or 8.83 Kgm / meter, so even if you somehow just allowed the end 1m to flex, you would likely be on the limit of the accuracy / noise / drift of a force sensor at 4 gm, 1part in 2000, which you may want to measure to 1%? An attempt to provide an offset force is limited by the thermal stabilty / compensation of the spring, which is done in a seismometer. In general, you can measure very small movements to a much higher accuracy than the direct measurement of force. I don't immediatly see how weight measurement on a half filled trough would be practicable. You would also have dynamic inertia effects. Maybe totally fill the column and use a differential pressure sensor at it's centre? Measure just the direct inbalance in the system? Regards, Chris Chapman In a message=20= dated 31/08/05, ian@........... writes:

I did a back-of-the-envelop= e calculation today for a 10 m long pipe,=20
15cm in diameter, half filled with liquid, sitting on 1 support at each=20
end. When the pipe is tilted by 1 micro radian, the difference in=20
loading between the posts is the equivalent of around 3 or 4 grams.

Could this be approached by monitoring the loading on the supports?

Ian Smith

Hi Ian,

      The total water mass would be about= 88.3 Kgm, or 8.83 Kgm / meter, so even if you somehow just allowed the end=20= 1m to flex, you would likely be on the limit of the accuracy / noise / drift= of a force sensor at 4 gm, 1part in 2000, which you may want to measure to=20= 1%? An attempt to provide an offset force is limited by the thermal stabilty= / compensation of the spring, which is done in a seismometer.=20
      In general, you can measure very sm= all movements to a much higher accuracy than the direct measurement of force= .. I don't immediatly see how weight measurement on a half filled trough woul= d be practicable. You would also have dynamic inertia effects. Maybe totally= fill the column and use a differential pressure sensor at it's centre? Meas= ure just the direct inbalance in the system?

      Regards,

      Chris Chapman

Subject: Re: Simple broadband Seismometer From: ian ian@........... Date: Thu, 01 Sep 2005 22:05:09 +0100 Hi, one assumption I made was that the mean signal, generated by the mean mass is subtracted and you are then only measuring the changes. If some piezo sensor can withstand a load generated by 44 Kg (2 supports), then 2 of them might give the required signal. By electrically differencing the signals from the 2 piezo sensors, the remainder is the changing mass + noise. Just a thought... Ian ChrisAtUpw@....... wrote: > In a message dated 31/08/05, ian@........... writes: > >> I did a back-of-the-envelope calculation today for a 10 m long pipe, >> 15cm in diameter, half filled with liquid, sitting on 1 support at each >> end. When the pipe is tilted by 1 micro radian, the difference in >> loading between the posts is the equivalent of around 3 or 4 grams. >> >> Could this be approached by monitoring the loading on the supports? >> >> Ian Smith > > > > Hi Ian, > > The total water mass would be about 88.3 Kgm, or 8.83 Kgm / > meter, so even if you somehow just allowed the end 1m to flex, you > would likely be on the limit of the accuracy / noise / drift of a > force sensor at 4 gm, 1part in 2000, which you may want to measure to > 1%? An attempt to provide an offset force is limited by the thermal > stabilty / compensation of the spring, which is done in a seismometer. > In general, you can measure very small movements to a much > higher accuracy than the direct measurement of force. I don't > immediatly see how weight measurement on a half filled trough would be > practicable. You would also have dynamic inertia effects. Maybe > totally fill the column and use a differential pressure sensor at it's > centre? Measure just the direct inbalance in the system? > > Regards, > > Chris Chapman > Hi,

one assumption I made was that the mean signal, generated by the mean mass is subtracted and you are then only measuring the changes. If some piezo sensor can withstand a load generated by 44 Kg (2 supports), then 2 of them might give the required signal. By electrically differencing the signals from the 2 piezo sensors, the remainder is the changing mass + noise. Just a thought...

Ian

ChrisAtUpw@....... wrote:
In a message dated 31/08/05, ian@........... writes:

I did a back-of-the-envelope calculation today for a 10 m long pipe,
15cm in diameter, half filled with liquid, sitting on 1 support at each
end. When the pipe is tilted by 1 micro radian, the difference in
loading between the posts is the equivalent of around 3 or 4 grams.

Could this be approached by monitoring the loading on the supports?

Ian Smith

Hi Ian,

      The total water mass would be about 88.3 Kgm, or 8.83 Kgm / meter, so even if you somehow just allowed the end 1m to flex, you would likely be on the limit of the accuracy / noise / drift of a force sensor at 4 gm, 1part in 2000, which you may want to measure to 1%? An attempt to provide an offset force is limited by the thermal stabilty / compensation of the spring, which is done in a seismometer.
      In general, you can measure very small movements to a much higher accuracy than the direct measurement of force. I don't immediatly see how weight measurement on a half filled trough would be practicable. You would also have dynamic inertia effects. Maybe totally fill the column and use a differential pressure sensor at it's centre? Measure just the direct inbalance in the system?

      Regards,

      Chris Chapman

Subject: Re: Simple broadband Seismometer From: ChrisAtUpw@....... Date: Thu, 1 Sep 2005 21:57:01 EDT In a message dated 01/09/2005, ian@........... writes: Hi, one assumption I made was that the mean signal, generated by the mean mass is subtracted and you are then only measuring the changes. If some piezo sensor can withstand a load generated by 44 Kg (2 supports), then 2 of them might give the required signal. By electrically differencing the signals from the 2 piezo sensors, the remainder is the changing mass + noise. Just a thought... Hi Ian, I don't really see why you need such a large pipe, when something nearer 1" would do fine. If you put on larger diameter end pots, you increase the period. Trying to match up two sensors allowing for temperature coefficients and drifts just doesn't work to better than about 0.1%. When it is dead easy to measure water levels to microns, why bother with weight sensors? The inexpensive piezo sensors drift in output voltage with temperature. There re plenty of problems in making precision measurements. 'Doing things the hard way' is just plain dumb. Regards, Chris Chapman
In a message dated 01/09/2005, ian@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Hi,
one assumption I made was that the mean signal, generated=20= by the=20 mean mass is subtracted and you are then only measuring the changes. = If=20 some piezo sensor can withstand a load generated by 44 Kg (2 supports), th= en 2=20 of them might give the required signal. By electrically differencing= the=20 signals from the 2 piezo sensors, the remainder is the changing mass +=20 noise. Just a thought...

Hi Ian,

    I don't really see why you need such a larg= e=20 pipe, when something nearer 1" would do fine. If you put on larger diam= eter=20 end pots, you increase the period.

    Trying to match up two sensors allowing=20 for temperature coefficients and drifts just doesn't work to better tha= n=20 about 0.1%.

    When it is dead easy to measure water level= s to=20 microns, why bother with weight sensors? The inexpensive piezo sensors=20 drift in output voltage with temperature.

    There re plenty of problems in making preci= sion=20 measurements. 'Doing things the hard way' is just plain dumb.

    Regards,

    Chris Chapman

Subject: Re: Simple broadband Seismometer From: Ian Smith ian@........... Date: Fri, 02 Sep 2005 08:00:12 +0100 Hi, excuse my dumbness! I'm treating this mailing list the same way I treat coffee time at work with my fellow engineers, as a forum for throwing up dumb ideas with the hope that about 1 in 10 fly (a reasonable rate). Specifically: The long length is to amplify the effect of very small tilts to the point that the effect is measurable. 10 m is a figure chosen for easy calculations. If the signals from the 2 piezo transducers are differenced then drifts and tempco's should cancel out. The discussions here on how to measure the effect the easy way seemed to be quite complicated. Longer periods are good! During the recent hurricane, my medium period sensor was useless whilst the professional long period devices rolled on. Having said all that, there's at least a 90% chance that my idea is indeed dumb! Pass the coffee... Ian ChrisAtUpw@....... wrote: > In a message dated 01/09/2005, ian@........... writes: > > Hi, > one assumption I made was that the mean signal, generated by the > mean mass is subtracted and you are then only measuring the > changes. If some piezo sensor can withstand a load generated by 44 > Kg (2 supports), then 2 of them might give the required signal. By > electrically differencing the signals from the 2 piezo sensors, the > remainder is the changing mass + noise. Just a thought... > > Hi Ian, > > I don't really see why you need such a large pipe, when something > nearer 1" would do fine. If you put on larger diameter end pots, you > increase the period. > Trying to match up two sensors allowing for temperature coefficients > and drifts just doesn't work to better than about 0.1%. > When it is dead easy to measure water levels to microns, why bother > with weight sensors? The inexpensive piezo sensors drift in output > voltage with temperature. > There re plenty of problems in making precision measurements. 'Doing > things the hard way' is just plain dumb. > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Simple broadband Seismometer From: Gordon Couger gcouger@.......... Date: Fri, 02 Sep 2005 03:16:38 -0500 Chris, I am late to the discussion so I have missed things. Are you using the principle of to cans with largo areas connect together by a tube with a very small diameter bore and an air bubble introduced into the bore will amplify the change in levels in one can related to the other and the change in the position of the bubble depends on the are of the can to the area of the tube connecting them. Fantastic amplification is possible with very simple tools. The surface of the bubble blocks nearly 100 % of the light shined on it so photocells or rotating photo paper can easily track the earths movements. Gordon ChrisAtUpw@....... wrote: > In a message dated 01/09/2005, ian@........... writes: > > Hi, > one assumption I made was that the mean signal, generated by the > mean mass is subtracted and you are then only measuring the > changes. If some piezo sensor can withstand a load generated by 44 > Kg (2 supports), then 2 of them might give the required signal. By > electrically differencing the signals from the 2 piezo sensors, the > remainder is the changing mass + noise. Just a thought... > > Hi Ian, > > I don't really see why you need such a large pipe, when something > nearer 1" would do fine. If you put on larger diameter end pots, you > increase the period. > Trying to match up two sensors allowing for temperature coefficients > and drifts just doesn't work to better than about 0.1%. > When it is dead easy to measure water levels to microns, why bother > with weight sensors? The inexpensive piezo sensors drift in output > voltage with temperature. > There re plenty of problems in making precision measurements. 'Doing > things the hard way' is just plain dumb. > > Regards, > > Chris Chapman > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Simple broadband Seismometer From: ChrisAtUpw@....... Date: Fri, 2 Sep 2005 06:08:02 EDT In a message dated 02/09/2005, ian@........... writes: Hi, I'm treating this mailing list the same way I treat coffee time at work with my fellow engineers, as a forum for throwing up dumb ideas with the hope that about 1 in 10 fly (a reasonable rate). Hi Ian, Great! This was what I was also trying to do! Specifically: The long length is to amplify the effect of very small tilts to the point that the effect is measurable. 10 m is a figure chosen for easy calculations. If the signals from the 2 piezo transducers are differenced then drifts and tempco's should cancel out. This involves two assumptions. Firstly that the two sensor locations 10 m apart do actually track in temperature to much better than 0.1 C Deg. The second is that both sensors have the same TC. In my experience, these are difficult / near impossible. Thermostatting a 10 m tube to a few 10s of milli degrees is likely to be rather expensive. The discussions here on how to measure the effect the easy way seemed to be quite complicated. Do enlighten me, please! Capacitative level sensors are quite standard technology. Longer periods are good! During the recent hurricane, my medium period sensor was useless whilst the professional long period devices rolled on. What sensors are you running / observing / commenting on? Having said all that, there's at least a 90% chance that my idea is indeed dumb! Pass the coffee... Ian Since you are planning to use an open trough, tilts / seismic waves which are slower than the natural period should be recorded OK. Faster signals develop travelling surface waves from both ends of the tube which are likely to be incoherent. See the Washington traces from the 26 Dec Sumatra quake. How are you planning to receive / analyse / suppress these faster surface travelling wave signals? My philosophy is to design out problems where possible. Pass the Aspirins... Regards, Chris Chapman
In a message dated 02/09/2005, ian@........... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Hi,
     I'm treating this mailing l= ist=20 the same way I treat coffee time at work with my fellow engineers, as a fo= rum=20 for throwing up dumb ideas with the hope that about 1 in 10 fly (a reasona= ble=20 rate).

Hi Ian,

    Great! This was what I was also trying to do! <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Specifically:

The long length is to amplify the effect of=20= very=20 small tilts to the point that the effect is measurable. 10 m is a fi= gure=20 chosen for easy calculations.

If the signals from the 2 piezo=20 transducers are differenced then drifts
and tempco's should cancel=20 out.
    This involves two assumptions. Firstly that the= two=20 sensor locations 10 m apart do actually track in temperature to much better=20= than=20 0.1 C Deg. The second is that both sensors have the same TC. In my experienc= e,=20 these are difficult / near impossible. Thermostatting a 10 m tube to a few 1= 0s=20 of milli degrees is likely to be rather expensive.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 discussions here on how to measure the effect the easy way seemed to
b= e=20 quite complicated.
    Do enlighten me, please! Capacitative level sen= sors=20 are quite standard technology.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Longer=20 periods are good! During the recent hurricane, my medium period=20
sensor was useless whilst the professional long period devices rolled=20 on.
    What sensors are you running / observing /=20 commenting on?
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Having=20 said all that, there's at least a 90% chance that my idea is
indeed=20 dumb!
Pass the coffee...
Ian

    Since you are planning to use an open trough, t= ilts=20 / seismic waves which are slower than the natural period should be recorded=20= OK.=20 Faster signals develop travelling surface waves from both ends of the tube w= hich=20 are likely to be incoherent. See the Washington traces from the 26=20 Dec Sumatra quake. How are you planning to receive / analyse / suppress= =20 these faster surface travelling wave signals?

    My philosophy is to design out problems where=20 possible. Pass the Aspirins...

    Regards,

    Chris Chapman
Subject: Re: Simple broadband Seismometer From: ChrisAtUpw@....... Date: Fri, 2 Sep 2005 16:35:35 EDT In a message dated 02/09/2005, gcouger@.......... writes: Chris, I am late to the discussion so I have missed things. Are you using the principle of two cans with large areas connect together by a tube with a very small diameter bore and an air bubble introduced into the bore will amplify the change in levels in one can related to the other and the change in the position of the bubble depends on the are of the can to the area of the tube connecting them. Fantastic amplification is possible with very simple tools. The surface of the bubble blocks nearly 100% of the light shined on it so photocells or rotating photo paper can easily track the earths movements. Gordon Hi Gordon, I am aware that it is possible to optically sense the ends of an air bubble in a tube, but I am rather doubtful if this would be practical in the middle of a seismometer. Air bubbles are inherently very compressible. Maybe a heavily dyed oil 'bubble' or some mercury would work? You can choose the diameter of the main tube to give roughly the correct damping. Without knowing the dimension of what you are calling 'a small diameter tube', I can't really comment. Ian was suggesting making a horizontal seismometer using a 15 cm dia tube, half filled with water and weighing the ends. Half filled sensor tubes are used in some large tiltmeters. I don't think that Ian had found space on the back of his envelope to do detailed analysis of issues like the end fittings, the type of sensor, the limits of accuracy and drift, or how such a system behaves dynamically, damping, wave formation, etc. I am not sure how you could support a 10m tube at the ends, without the centre section oscillating like fun. I hope that Ian can produce a full scale working model and measure it's performance. I did a back-of-the-envelope calculation today for a 10 m long pipe, 15cm in diameter, half filled with liquid, sitting on 1 support at each end. When the pipe is tilted by 1 micro radian, the difference in loading between the posts is the equivalent of around 3 or 4 grams. Could this be approached by monitoring the loading on the supports? Ian Smith _ChrisAtUpw@........ (mailto:ChrisAtUpw@........ wrote: > In a message dated 01/09/2005, ian@........... writes: > > Hi, > one assumption I made was that the mean signal, generated by the > mean mass is subtracted and you are then only measuring the > changes. If some piezo sensor can withstand a load generated by 44 > Kg (2 supports), then 2 of them might give the required signal. By > electrically differencing the signals from the 2 piezo sensors, the > remainder is the changing mass + noise. Just a thought... > > Hi Ian, > > I don't really see why you need such a large pipe, when something > nearer 1" would do fine. If you put on larger diameter end pots, you > increase the period. > Trying to match up two sensors allowing for temperature coefficients > and drifts just doesn't work to better than about 0.1%. > When it is dead easy to measure water levels to microns, why bother > with weight sensors? The inexpensive piezo sensors drift in output > voltage with temperature. > There are plenty of problems in making precision measurements. 'Doing > things the hard way' is just plain dumb. Regards, Chris Chapman
In a message dated 02/09/2005, gcouger@.......... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Chris,

I am late to the discussion so I have missed things= .. Are=20 you using the principle of two cans with large areas connect together=20 by a tube with a very small diameter bore and an air bubble introduce= d=20 into the bore will amplify the change in levels in
one can related to=20= the=20 other and the change in the position of the bubble depends on the are of t= he=20 can to the area of the tube connecting them.

Fantastic amplificatio= n is=20 possible with very simple tools. The surface of the bubble blocks nearly 1= 00%=20 of the light shined on it so photocells or rotating photo paper can easily= =20 track the earths movements.

Gordon
Hi Gordon,

    I am aware that it is possible to optically sen= se=20 the ends of an air bubble in a tube, but I am rather doubtful if this would=20= be=20 practical in the middle of a seismometer. Air bubbles are inherently very=20 compressible. Maybe a heavily dyed oil 'bubble' or some mercury would work?=20= You=20 can choose the diameter of the main tube to give roughly the correct=20 damping. Without knowing the dimension of what you are calling 'a=20 small diameter tube', I can't really comment.

    Ian was suggesting making a horizontal seismome= ter=20 using a 15 cm dia tube, half filled with water and weighing the ends. H= alf=20 filled sensor tubes are used in some large tiltmeters. I don'= t=20 think that Ian had found space on the back of his envelope to do detail= ed=20 analysis of issues like the end fittings, the type of sensor, the limits of=20 accuracy and drift, or how such a system behaves dynamically, damping, wave=20 formation, etc. I am not sure how you could support a 10m tube at the ends,=20 without the centre section oscillating like fun.

    I hope that Ian can produce a full scale workin= g=20 model and measure it's performance.

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I did a=20 back-of-the-envelope calculation today for a 10 m long pipe, 15cm in diame= ter,=20 half filled with liquid, sitting on 1 support at each end. When the=20= pipe=20 is tilted by 1 micro radian, the difference in loading between the posts i= s=20 the equivalent of around 3 or 4 grams.
Could this be approached by=20 monitoring the loading on the supports?
Ian Smith <= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>ChrisAtUpw@....... wrote:
> I= n a=20 message dated 01/09/2005, ian@........... writes:
>
> =20    Hi,
>    one assumption I made was that= the=20 mean signal, generated by the
>    mean mass is=20 subtracted and you are then only measuring the
>   =20 changes. If some piezo sensor can withstand a load generated by=20 44
>    Kg (2 supports), then 2 of them might give t= he=20 required signal. By
>    electrically differen= cing=20 the signals from the 2 piezo sensors, the
>    remai= nder=20 is the changing mass + noise. Just a thought...
>
> Hi=20 Ian,
>
>    I don't really see why you need su= ch a=20 large pipe, when something
> nearer 1" would do fine. If you put on=20 larger diameter end pots, you
> increase the period.
> =20    Trying to match up two sensors allowing for temperature=20 coefficients
> and drifts just doesn't work to better than about=20 0.1%.
>    When it is dead easy to measure water lev= els=20 to microns, why bother
> with weight sensors? The inexpensive piezo=20 sensors drift in output
> voltage with temperature.
> =20    There are plenty of problems in making precision measurements= ..=20 'Doing
> things the hard way' is just plain dumb.

    Regards,

    Chris Chapman
Subject: Re: Simple broadband Seismometer From: Gordon Couger gcouger@.......... Date: Fri, 02 Sep 2005 23:15:30 -0500 Chris, See: www.sas.org/E-Bulletin/2001-10-05/labNotes2/labNotes.html The small tube is typically a glass tube drawn down to less than ..01 inch diameter maybe a lot smaller. The bubble is injected in one end an moved to the center by adding fluid drop by drop. The miscues formed by the air water interface makes a large dark band across a sensor just try it with a laser pointer and glass of water. In fact the shadow of the air water interface is so large it is a problem to get very much dynamic range over the range of a CCD sensor unless you look at just one edge of the water bubble. Temperature would be more of problem than pressure on the size of the bubble. But if the two edges of the bubble are both tracked the bubble size can be canceled out. This would take a rather complex machine vision project. Not beyond the means of an amateur but rather ambitious on any level as a complete problem. A more realistic solution may be use a very thin grade of oil and steel piston between a pair of coils on the tube to sense the its movement and position by using the coils in an AC bridge circuit. The tube could be brass, aluminum, or any non magnetic material and the piston any magnetic material. The problem is with more crap than there is with a bubble. Sensing the potion of a bubble in a magnetic guild might be easier than sensing one with light if you can find a magnetic guild that keeps the partials in suspension over a long term. Gordon ChrisAtUpw@....... wrote: > In a message dated 02/09/2005, gcouger@.......... writes: > > Chris, > > I am late to the discussion so I have missed things. Are you using > the principle of two cans with large areas connect together by a > tube with a very small diameter bore and an air bubble introduced > into the bore will amplify the change in levels in > one can related to the other and the change in the position of the > bubble depends on the are of the can to the area of the tube > connecting them. > > Fantastic amplification is possible with very simple tools. The > surface of the bubble blocks nearly 100% of the light shined on it > so photocells or rotating photo paper can easily track the earths > movements. > > Gordon > > Hi Gordon, > > I am aware that it is possible to optically sense the ends of an air > bubble in a tube, but I am rather doubtful if this would be practical in > the middle of a seismometer. Air bubbles are inherently very > compressible. Maybe a heavily dyed oil 'bubble' or some mercury would > work? You can choose the diameter of the main tube to give roughly the > correct damping. Without knowing the dimension of what you are calling > 'a small diameter tube', I can't really comment. > > Ian was suggesting making a horizontal seismometer using a 15 cm dia > tube, half filled with water and weighing the ends. Half filled sensor > tubes are used in some large tiltmeters. I don't think that Ian had > found space on the back of his envelope to do detailed analysis of > issues like the end fittings, the type of sensor, the limits of accuracy > and drift, or how such a system behaves dynamically, damping, wave > formation, etc. I am not sure how you could support a 10m tube at the > ends, without the centre section oscillating like fun. > > I hope that Ian can produce a full scale working model and measure > it's performance. > > I did a back-of-the-envelope calculation today for a 10 m long pipe, > 15cm in diameter, half filled with liquid, sitting on 1 support at > each end. When the pipe is tilted by 1 micro radian, the difference > in loading between the posts is the equivalent of around 3 or 4 grams. > Could this be approached by monitoring the loading on the supports? > Ian Smith > > ChrisAtUpw@....... wrote: > > In a message dated 01/09/2005, ian@........... writes: > > > > Hi, > > one assumption I made was that the mean signal, generated by the > > mean mass is subtracted and you are then only measuring the > > changes. If some piezo sensor can withstand a load generated > by 44 > > Kg (2 supports), then 2 of them might give the required > signal. By > > electrically differencing the signals from the 2 piezo > sensors, the > > remainder is the changing mass + noise. Just a thought... > > > > Hi Ian, > > > > I don't really see why you need such a large pipe, when something > > nearer 1" would do fine. If you put on larger diameter end pots, you > > increase the period. > > Trying to match up two sensors allowing for temperature > coefficients > > and drifts just doesn't work to better than about 0.1%. > > When it is dead easy to measure water levels to microns, why > bother > > with weight sensors? The inexpensive piezo sensors drift in output > > voltage with temperature. > > There are plenty of problems in making precision > measurements. 'Doing > > things the hard way' is just plain dumb. > > Regards, > > Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Simple broadband Seismometer From: ChrisAtUpw@....... Date: Sat, 3 Sep 2005 12:08:05 EDT In a message dated 03/09/2005, gcouger@.......... writes: Chris, See: www.sas.org/E-Bulletin/2001-10-05/labNotes2/labNotes.html The small tube is typically a glass tube drawn down to less than ..01 inch diameter maybe a lot smaller. The bubble is injected in one end an moved to the center by adding fluid drop by drop. The bubble will move by 1/2 the volume of the drop, but you can get some stiction. This may be serious in tubes of 1 mm or less. The miscues formed by the air water interface makes a large dark band across a sensor just try it with a laser pointer and glass of water. In fact the shadow of the air water interface is so large it is a problem to get very much dynamic range over the range of a CCD sensor unless you look at just one edge of the water bubble. Temperature would be more of problem than pressure on the size of the bubble. But if the two edges of the bubble are both tracked the bubble size can be canceled out. This would take a rather complex machine vision project. Try a couple of Si photocells? You can buy them 1" long x 0.1" wide. A more realistic solution may be use a very thin grade of oil and steel piston between a pair of coils on the tube to sense the its movement..... No. You need to eliminate all mechanical friction. This could be done with mercury, sensing the end of the column either optically or capacitatively. Another way would be to use metal bellows and sense the position of the closed end. What is "a magnetic guild"? Regards, Chris Chapman
In a message dated 03/09/2005, gcouger@.......... writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Chris,

See:=20 www.sas.org/E-Bulletin/2001-10-05/labNotes2/labNotes.html

The small= =20 tube is typically a glass tube drawn down to less than
.01 inch diamet= er=20 maybe a lot smaller. The bubble is injected in
one end an moved to the= =20 center by adding fluid drop by drop.
    The bubble will move by 1/2 the volume of the d= rop,=20 but you can get some stiction. This may be serious in tubes of 1 mm or=20 less.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 miscues formed by the air water interface makes a large dark
band acro= ss a=20 sensor just try it with a laser pointer and glass
of water. In fact th= e=20 shadow of the air water interface is so
large it is a problem to get v= ery=20 much dynamic range over the
range of a CCD sensor unless you look=20 at just one edge of the
water bubble.

Temperature would be= =20 more of problem than pressure on the size
of the bubble. But if the tw= o=20 edges of the bubble are both
tracked the bubble size can be canceled o= ut.=20 This would take a
rather complex machine vision project.=20
    Try a couple of Si photocells? You can buy them= 1"=20 long x 0.1" wide.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>A more=20 realistic solution may be use a very thin grade of oil and steel piston=20 between a pair of coils on the tube to sense the its movement.....=20
    No. You need to eliminate all mechanical=20 friction. This could be done with mercury, sensing the end of the=20 column either optically or capacitatively.

    Another way would be to use metal bellows and s= ense=20 the position of the closed end.

    What is "a magnetic guild"?

    Regards,

    Chris Chapman

Subject: Morrisey's seismometer From: alexander mirabal alexmirabal2000@........ Date: Mon, 5 Sep 2005 02:16:41 +0200 (CEST) Hello List Members: My name is Alexander Mirabal, (cuban, electronic engineer.) and I live in M�xico. I'm new in amateur seismography and at present I try to study the design of simple homemade systems and planning the construction of my first sensor. I recently know about the High Resolution Broadband Seismometer designed by Sean-Thomas Morrissey. I got from the web some drawings and explanations related to this design, but I would like to get a better knowledge (maybe a more detailed explanation) of the mechanic part: Transfer Function and its mathematical components, how to calculate free period experimentally, etc... Here in M�xico is really hard to get books and magazines recomend in most of the technical papers. I will appreciate any help (comments, links, drawings in electronic format, etc) from any of you regarding Morrisey's seismometer. I would like to build one.Electronic is not a concern for me because that is my background. Actually I am planning to implement some parts of the system using microcontrollers (PICs from Microchip) to interface A/D block and data logger, etc... Hoping you excuse my poor English, Thanks in advance Alexander --------------------------------- Correo Yahoo! Comprueba qu� es nuevo, aqu� http://correo.yahoo.es

Hello List Members:

My name is Alexander Mirabal, (cuban, electronic engineer.) and I live in M�xico.

I'm new in amateur seismography and at present I try to study the design of simple homemade systems and planning the construction of my first sensor.

I recently know about the High Resolution Broadband Seismometer designed by Sean-Thomas Morrissey. I got from the web some drawings and explanations related to this design, but I would like to get a better knowledge (maybe a more detailed explanation) of the mechanic part: Transfer Function and its mathematical components, how to calculate free period experimentally, etc...

Here in M�xico is really hard to get books and magazines recomend in most of the technical papers. I will appreciate any help (comments, links, drawings in electronic format, etc) from any of you regarding Morrisey's seismometer. I would like to build one.Electronic is not a concern for me because that is my background. Actually I am planning to implement some parts of the system using microcontrollers (PICs from Microchip) to interface A/D block and data logger, etc...

Hoping you excuse my poor English,

Thanks in advance

Alexander

Correo Yahoo!
Comprueba qu� es nuevo, aqu�
http://correo.yahoo.es Subject: Re: Morrisey's seismometer From: Brett Nordgren Brett3kg@............. Date: Mon, 05 Sep 2005 09:16:32 -0400 At 02:16 AM 9/5/2005 +0200, you wrote: >Hello List Members: > >My name is Alexander Mirabal, (cuban, electronic engineer.) and I live in= =20 >M=E9xico. > >I'm new in amateur seismography and at present I try to study the design=20 >of simple homemade systems and planning the construction of my first= sensor. Hi Alexander, I have a few files on my Web site that you may want to download that go=20 into Sean-Thomas' design. Feedback sesimometers are great, but they have=20 to be designed quite carefully to avoid on the one hand, poor performance=20 and on the other, having a nothing more than a very expensive=20 oscillator. At http://bnordgren.org/seismo/ I have posted a list of=20 files you can download. In particular: "loop3.pdf" and "Vertgeom.pdf" may help, and possibly=20 "feedback.pdf" and "complex.pdf" may provide some background, though as an= =20 EE you probably have already studied most of that stuff already. Also the= =20 "STS1" files are my attempt at a mechanical analysis of the Streckeisen=20 STS-1 leaf-spring vertical. Its most obvious difference from the STM-8 is= =20 that the STS-1 uses a fixed-end leaf spring, which would likely be harder=20 to build and adjust, but it is a very elegant design that obviously has=20 worked extremely well. And there are probably some other files there that you might find= interesing. One problem I ran into is that I never could find an "official" set of=20 schematics for S-T's design. There are many versions with ongoing=20 revisions. Perhaps someone on the list has one they would like to=20 contribute, to be defined as the official version. Also, if you haven't already, you will probably want to look at Prof. Erich= =20 Weilandt's comprehensive article at=20 http://www.geophys.uni-stuttgart.de/seismometry/man_html/ Hope this helps. Brett If my e-mail address above is not working you can always reach my mail form at: http://bnordgren.org/contactB.html using your Web browser. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Morrisey's seismometer From: ChrisAtUpw@....... Date: Mon, 5 Sep 2005 10:33:48 EDT In a message dated 05/09/2005, alexmirabal2000@........ writes: I got from the web some drawings and explanations related to this design, but I would like to get a better knowledge (maybe a more detailed explanation) of the mechanic part: Transfer Function and its mathematical components, how to calculate free period experimentally, etc... Dear Alexander, The principles of the STM-8 are essentially similar as those of the La Coste vertical seismometer published in 1935. You have an ~horizontal arm with a seismic mass on the end. You need to support it in such a way that the forces are nearly, but not quite, compensated out as the beam angle changes. La Coste wound his spring so that the whole assembly had 'zero length'. This means that the load / length graph goes through the point zero force / zero length. Most coil springs have a minimum physical length, so they require a 'pre tension' type winding. (You can also wind flat spiral springs.) In the STM-8 setup, you use a flat strip bent into about 3/4 circle and positioned at an angle under the beam, with low torque foil suspensions. This extreme bend gives a load /extension graph which you can match up to the torque / angle graph due to the seismic mass. If they matched identically, you would have no net torque as the angle changed and hence an infinite period. The problem with this is that steel spring constants are temperature sensitive, but don't match those of the mass + arm, so it is only 'stable' over a few C deg range. The more precise the balance and the longer the period, the greater the influence of the temperature variations. However, you can get a very considerable improvement by using the spring material Ni-SpanC, which has a very low temperature coefficient. Two leaf springs are sometimes used to provide a greater compensation accuracy. The position of the arm needs to be critically damped to give stable operation - as does any oscillatory system. The alternative Sean uses is to provide electronic position sensing down to maybe 1 nano metre and force feedback, usually electro-magnetic, to stabilise the mechanical system and to define it's period. The damping may be purely feedback or magnet / plate inductive type. (Don't ever try to use oil damping!) The electronic constants and feedback gain override the mechanical properties. Electronic feedback damping gives more noise on the signal and a more complicated circuit, but it is widely used. I hope that this provides some background knowledge for you. Regards, Chris Chapman

In a message dated 05/09/2005, alexmirabal2000@........ writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>I got from the web some drawings and explanations relat= ed to=20 this design, but I would like to get a better knowledge (maybe a more deta= iled=20 explanation) of the mechanic part: Transfer Function and its mathemat= ical=20 components, how to calculate free period experimentally, etc...=20

Dear Alexander,

    The principles of the STM-8 are=20 essentially similar as those of the La Coste vertical seismometer publi= shed=20 in 1935.

    You have an ~horizontal arm with a seismic mass= on=20 the end. You need to support it in such a way that the forces are nearly, bu= t=20 not quite, compensated out as the beam angle changes. La Coste wound his spr= ing=20 so that the whole assembly had 'zero length'. This means that the load / len= gth=20 graph goes through the point zero force / zero length. Most coil spring= s=20 have a minimum physical length, so they require a 'pre tension' type=20 winding. (You can also wind flat spiral springs.)

    In the STM-8 setup, you use a flat strip bent i= nto=20 about 3/4 circle and positioned at an angle under the beam, with low torque=20= foil=20 suspensions. This extreme bend gives a load /extension graph which you can m= atch=20 up to the torque / angle graph due to the seismic mass. If they matched= =20 identically, you would have no net torque as the angle changed and henc= e an=20 infinite period. The problem with this is that steel spring constants are=20 temperature sensitive, but don't match those of the mass + arm, so it is onl= y=20 'stable' over a few C deg range. The more precise the balance and the longer= the=20 period, the greater the influence of the temperature variations. Howeve= r,=20 you can get a very considerable improvement by using the spring material=20 Ni-SpanC, which has a very low temperature coefficient. Two leaf springs are= =20 sometimes used to provide a greater compensation accuracy. The position of t= he=20 arm needs to be critically damped to give stable operation - as does any=20 oscillatory system.

    The alternative Sean uses is to provide=20 electronic position sensing down to maybe 1 nano metre and force feedba= ck,=20 usually electro-magnetic, to stabilise the mechanical system and to define i= t's=20 period. The damping may be purely feedback or magnet / plate inductive=20 type. (Don't ever try to use oil damping!) The electronic constants and= =20 feedback gain override the mechanical properties. Electronic feedback dampin= g=20 gives more noise on the signal and a more complicated circuit, but it is wid= ely=20 used.

    I hope that this provides some background knowl= edge=20 for you.

    Regards,

    Chris Chapman
Subject: Re: Morrisey's seismometer From: alexander mirabal alexmirabal2000@........ Date: Tue, 6 Sep 2005 04:54:09 +0200 (CEST) Dear Brett: I sincerely thank you for your detailed technical comments, the files you suggest me and specially your interest in making my first steps easier. You got the right sense of what I want. I don�t want to merely reproduce a design ignoring how it works. I absolutely need to know it before go into the construction..! I already downloaded the files from your web site. Considering the titles, I think they effectively cover important topics for my learning purpose. My original interest in STM-8 was basically as a model to understand the theory behind the mechanism, especially because of the use of electro-magnetic resources to stabilize and define the period of the mechanical system, and provide damping. Just because of my background, I thought it would be not only familiar for me, but easier to understand the global performance and its implementation. I honestly feel engage with this matter and I will really go as deep as possible into the amount of useful theory I already have at hand. I also hope you let me to be in touch with you in the near future, probably with new questions or may be partial results of the work. Finally, I want to express to you that I am gratefully surprised and thanked because of the number of sincere, respectful and technically deep mails like your I have received in less than 24 hours from different members of the list. Thanks you Very best regards Alexander --------------------------------- Correo Yahoo! Comprueba qu� es nuevo, aqu� http://correo.yahoo.es

Dear Brett:

I sincerely thank you for your detailed technical comments, the files you suggest me and specially your interest in making my first steps easier.

You got the right sense of what I want. I don�t want to merely reproduce a design ignoring how it works. I absolutely need to know it before go into the construction..! I already downloaded the files from your web site. Considering the titles, I think they effectively cover important topics for my learning purpose.

My original interest in STM-8 was basically as a model to understand the theory behind the mechanism, especially because of the use of electro-magnetic resources to stabilize and define the period of the mechanical system, and provide damping. Just because of my background, I thought it would be not only familiar for me, but easier to understand the global performance and its implementation.

I honestly feel engage with this matter and I will really go as deep as possible into the amount of useful theory I already have at hand. I also hope you let me to be in touch with you in the near future, probably with new questions or may be partial results of the work.

Finally, I want to express to you that I am gratefully surprised and thanked because of the number of sincere, respectful and technically deep mails like your I have received in less than 24 hours from different members of the list.

Thanks you

Very best regards

Alexander

Correo Yahoo!
Comprueba qu� es nuevo, aqu�
http://correo.yahoo.es Subject: Re: Morrisey's seismometer From: Brett Nordgren Brett3kg@............. Date: Tue, 06 Sep 2005 13:02:48 -0400 Alexander, At 04:54 AM 9/6/2005 +0200, you wrote: >Dear Brett: >I sincerely thank you for your detailed technical comments, the files you >suggest me and specially your interest in making my first steps easier. You are very welcome. Always happy to help a fellow experimenter. >You got the right sense of what I want. I don't want to merely reproduce a >design ignoring how it works. I absolutely need to know it before go into >the construction..! I already downloaded the files from your web site. >Considering the titles, I think they effectively cover important topics >for my learning purpose. I, like you, prefer to understand how things work before I jump in and start building. Unfortunately, usually that means that I only get as far as the analysis and planning, and rarely get around to actually building things. At least I can help pass along what I have discovered so far. I hope you understand that I am expecting people to ask questions about the information I have put on the Web site. I deliberately left out some things that I thought might be confusing to beginners. Other things I have undoubtedly left out by accident, and there are certainly some errors. Please do not hesitate to ask about things that are wrong, or that I had omitted or didn't make clear. In that regard, I think particularly about the STS-1 Excel spread sheet. It uses a number of Excel features (macros, etc.) that need to be set up properly. When I was first developing the system, it took me several weeks, making about every mistake possible, to finally get it to work. At least now I know many things which can go wrong. I have assumed that anyone who is trying to make that one work, will be asking me for help. And also it is not very user-friendly. But it does solve an interesing problem. >My original interest in STM-8 was basically as a model to understand the >theory behind the mechanism, especially because of the use of >electro-magnetic resources to stabilize and define the period of the >mechanical system, and provide damping. Just because of my background, I >thought it would be not only familiar for me, but easier to understand the >global performance and its implementation. A couple of comments on the STM-8 design. One critical factor, that was not directly addressed much is that of mechanical resonances. With the feedback design, they ultimately will be a big limiting factor on how well you can make the instrument work, particularly at the higher frequencies. It would be nice if there could be no big resonances below 1000 Hz, though that's going to be hard to achieve with the long, thin boom of the STM-8. Also, temperature effects are going to limit performance. Designing an enclosure which can be regulated to a few thousandths of a degree, with minimum internal convection, will help a lot. Also keeping all heat sources, except for the temperature-sensitive parts, outside the enclosure will be a good idea. Finally, I think that the circuit needs more gain in the region below 1Hz, and more current drive capability. There was some debate about whether doing that would introduce additional noise, but I believe that it should be possible without too much difficulty. I'm sure that you can create a workable instrument without much concern for the above issues, but for top performance they probably would want to be considered. Regards, Brett ----- If my e-mail address above is not working you can always reach my mail form at: http://bnordgren.org/contactB.html using your Web browser. Alexander,

At 04:54 AM 9/6/2005 +0200, you wrote:

Dear Brett:
I sincerely thank you for your detailed technical comments, the files you suggest me and specially your interest in making my first steps easier.

You are very welcome. Always happy to help a fellow experimenter.

You got the right sense of what I want. I don�t want to merely reproduce a design ignoring how it works. I absolutely need to know it before go into the construction..! I already downloaded the files from your web site. Considering the titles, I think they effectively cover important topics for my learning purpose.

I, like you, prefer to understand how things work before I jump in and start building. Unfortunately, usually that means that I only get as far as the analysis and planning, and rarely get around to actually building things. At least I can help pass along what I have discovered so far.

I hope you understand that I am expecting people to ask questions about the information I have put on the Web site. I deliberately left out some things that I thought might be confusing to beginners. Other things I have undoubtedly left out by accident, and there are certainly some errors. Please do not hesitate to ask about things that are wrong, or that I had omitted or didn't make clear.

In that regard, I think particularly about the STS-1 Excel spread sheet. It uses a number of Excel features (macros, etc.) that need to be set up properly. When I was first developing the system, it took me several weeks, making about every mistake possible, to finally get it to work. At least now I know many things which can go wrong. I have assumed that anyone who is trying to make that one work, will be asking me for help. And also it is not very user-friendly. But it does solve an interesing problem.

My original interest in STM-8 was basically as a model to understand the theory behind the mechanism, especially because of the use of electro-magnetic resources to stabilize and define the period of the mechanical system, and provide damping. Just because of my background, I thought it would be not only familiar for me, but easier to understand the global performance and its implementation.

A couple of comments on the STM-8 design. One critical factor, that was not directly addressed much is that of mechanical resonances. With the feedback design, they ultimately will be a big limiting factor on how well you can make the instrument work, particularly at the higher frequencies. It would be nice if there could be no big resonances below 1000 Hz, though that's going to be hard to achieve with the long, thin boom of the STM-8.

Also, temperature effects are going to limit performance. Designing an enclosure which can be regulated to a few thousandths of a degree, with minimum internal convection, will help a lot. Also keeping all heat sources, except for the temperature-sensitive parts, outside the enclosure will be a good idea.

Finally, I think that the circuit needs more gain in the region below 1Hz, and more current drive capability. There was some debate about whether doing that would introduce additional noise, but I believe that it should be possible without too much difficulty.

I'm sure that you can create a workable instrument without much concern for the above issues, but for top performance they probably would want to be considered.

Regards,
Brett

-----

If my e-mail address above is not working you can always reach my mail form
at: http://bnordgren.org/contactB.html
using your Web browser. Subject: Building the STM-8 From: Mike Speed mike8s2@......... Date: Thu, 8 Sep 2005 13:52:01 -0700 (PDT) I am working on an STM-8 - all the mechanical is done and I'm in the process of preparing an order for the electronics. In the meantime, I connected the Feedback transducer (the speaker was the only "electronics" I had for it so far) to my recorder. I'm getting real nice low frequency signals from it. I can see from 30 seconds to 500 Hz. The roll off: 30 seconds is at -30db relative, 1 Hz is at about -35db relative, then, it really rolls off after 4 Hz. I can see a small peak at 2.3 seconds - the period of the seismometer. I'm using a modified sound card to display/record the signal. I built a low-frequency oscillator to check the response of the sound card - works great. Anyway, I thought it was interesting to get such a good signal from just the feedback transducer and I thought you all might like to know. Greg __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Very Simple Sensor From: John or Jan Lahr JohnJan@........ Date: Sat, 10 Sep 2005 22:45:23 -0700 In early August I mentioned the "quick and easy" seismic sensor that I've been working on. After the recent Mw 7.7 earthquake in P.N.G., I'm now confident that it works. Background noise is the biggest problem that I see at this time, and that may be due to the poor location of the sensor on a table on the third floor of the town house where I'm currently living. I'll be moving to a house soon, and will see how it works in a quieter location. See the "Version 3" pictures and recent seismograms here: http://jclahr.com/science/psn/wooden/ . This is similar to the vertical that Dewayne Hill built and has described here: http://jclahr.com/science/psn/hill/index.html Dewayne, if you're still on this list, what is your current E-mail address?? Cheers, John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: "Geoff" gmvoeth@........... Date: Sun, 11 Sep 2005 11:10:19 -0700 The sensor really must be isolated from structures or foundations of structures you need to be on or under the ground away from trees and buildings and other things which are affected by wind or foot or other traffic. If you can get isolated just 15 linear feet away onto bare ground that is better then simply moving from one building to another. Bedrock is probably the single best thing you could find. 'Chuckle' Bedrock reminds me of Fred Flinstone. The code phrase for today is 'Quiet Bedrock'. My Air conditioner unit is vibrationally coupled to the slab upon which my home resides so there is no quiet place I can put my geophone within 20 feet of the electronics. Awnings and mobile homes couple wind noise to the slab. If I had known what I know now I would have built a special isolated Vault just for the geophone away from Water pipes with their water hammer and electrical entrance with the 60Hz noise. Sincerely; gmvoeth > I'm now confident that it works. Background noise is the biggest > problem that I see at this time, and that may be due to the poor > location of the sensor on a table on the third floor of the town > house where I'm currently living. I'll be moving to a house soon, > and will see how it works in a quieter location. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: meredith lamb paleoartifact@......... Date: Mon, 12 Sep 2005 11:30:16 -0600 Hi John, Your new "wooden" hinge approach; (See: http://jclahr.com/science/psn/wooden/target14.html) is so similar to your older excellent hinge for horizontals; (See: http"//jclahr.com.science/psn/gate.html) that it could indeed be quite worthwhile to continue the fine work, and/or do more R&D to see how variations of your original might also work. Just from looking at it...I suspect one might even be able to put typical "loose" nuts on the ends of the bolts, just to hold the wire? Another possible approach could be using a ~ long spacer with internal end threaded holes. A drilled perpendicular hole near the ends could contain the wire; where a inserted screw in the ends would clamp/lock down on the wire. One could also put a setscrew down in the threaded holes just past the drilled holes, and use another screw to clamp down on the wire also for=20 better wire holding. Just a thought..... Take care, Meredith Lamb On 9/10/05, John or Jan Lahr wrote: >=20 > In early August I mentioned the "quick and easy" seismic sensor that > I've been working on. After the recent Mw 7.7 earthquake in P.N.G., > I'm now confident that it works. Background noise is the biggest > problem that I see at this time, and that may be due to the poor > location of the sensor on a table on the third floor of the town > house where I'm currently living. I'll be moving to a house soon, > and will see how it works in a quieter location. >=20 > See the "Version 3" pictures and recent seismograms here: > http://jclahr.com/science/psn/wooden/ . >=20 > clip..... >=20 >=20 >=20 > Hi John,

Your new "wooden" hinge approach;

(See: = http://jclahr.com/science/psn/wooden/target14.html)

is so similar to your older excellent hinge for horizontals;

(See: http"//jclahr.com.science/psn/gate.html)

that it could indeed be quite worthwhile to continue the fine
work, and/or do more R&D to see how variations of your
original might also work.

Just from looking at it...I suspect one might even be able to
put typical "loose" nuts on the ends of the bolts, just to hold the wire?

Another possible approach could be using a ~ long spacer with
internal end threaded holes. A drilled perpendicular hole near
the ends could contain the wire; where a inserted screw in the
ends would clamp/lock down on the wire. One could also put a
setscrew down in the threaded holes just past the drilled holes,
and use another screw to clamp down on the wire also for
better wire holding. Just a thought.....

Take care, Meredith Lamb

On 9/10/05, John or Jan Lahr <= JohnJan@........> wrote:
In early August I mentioned the "quick and easy" seismic sensor t= hat
I've been working on.  After the recent Mw 7.7 earthquake = in P.N.G.,
I'm now confident that it works.  Background noise = is the biggest
problem that I see at this time, and that may be due to the poor
locatio= n of the sensor on a table on the third floor of the town
house where I'= m currently living.  I'll be moving to a house soon,
and will = see how it works in a quieter location.

See the "Version 3" pictures and recent seismograms here:=
http://jclahr.com/sci= ence/psn/wooden/ .

clip.....

Subject: [Fwd: additional hurricane studies] From: Larry Cochrane lcochrane@.............. Date: Wed, 14 Sep 2005 18:14:57 -0700 FYI.. -Larry --------------------------------------------------------------------------- Hi Larry. With all the attention given to hurricane Katrina (and now, increasingly of Ophelia as it is battering the Carolinas) you may be interested in my latest paper, titled "Hurricanes and Earth hum", online at http://arxiv.org/html/physics/0509103 The records for this paper were taken with my 'modernized conventional pendulum', some pictures of which are posted to this arxiv site. The pendulum was featured in the April issue of the Popular Science article titled "Affordable earthquake detector", concerned with last year's tsunami. Feel free to mention this research on the PSN mailing list if you so choose. Thanks for your interest and best regards, Randall __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Experiment From: Alexandr Yagodin midia@.............. Date: Thu, 15 Sep 2005 21:34:49 +0200 Hi to All!!! I make small experiment. I should see sesmogramms for last days in area of Europe, Africa, Asia. Whether someone can give advice, where it can be seen? Best regards Alexandr ----- Original Message ----- From: "Gordon Couger" To: Sent: Saturday, September 03, 2005 6:15 AM __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Experiment From: "Geoff" gmvoeth@........... Date: Thu, 15 Sep 2005 20:16:15 -0700 > I make small experiment. I should see sesmogramms for last days in area of > Europe, Africa, Asia. Whether someone can give advice, where it can be seen? > > Best regards > > Alexandr > http://earthquake.usgs.gov/ this should point you in the right direction. It will lead you other sites of interest. Sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: [Fwd: additional hurricane studies] From: meredith lamb paleoartifact@......... Date: Fri, 16 Sep 2005 00:32:18 -0600 Hi all, Was particularly interested in the pendulum hinge; but, the photos don't= =20 seem to totally show exactly how they maintain position or their contact shape o= r=20 the adjacent "supports" they rest on. Indeed....the supports may well be glass but its= =20 just a guess, or, they are made of angled metal? I see no grooves in the supports= =20 to keep the hinge in its centralized placement. Perhaps the hinge contact points ar= e=20 simply like ball bearings? Has anybody seem the April issue of Popular Science magazine, where it "hopefully" shows the seismometer"? If so, is it like the referenced web page below?=20 Take care, Meredith Lamb On 9/14/05, Larry Cochrane wrote:=20 >=20 >=20 > FYI.. -Larry >=20 > -------------------------------------------------------------------------= -- > Hi Larry. > With all the attention given to hurricane Katrina (and now, increasingly= =20 > of Ophelia > as it is battering the Carolinas) you may be interested in my latest=20 > paper, titled > "Hurricanes and Earth hum", online at=20 > http://arxiv.org/html/physics/0509103 > The records for this paper were taken with my 'modernized conventional > pendulum', some pictures of which are posted to this arxiv site. The=20 > pendulum was > featured in the April issue of the Popular Science article titled=20 > "Affordable > earthquake detector", concerned with last year's tsunami. > Feel free to mention this research on the PSN mailing list if you so=20 > choose. > Thanks for your interest and best regards, > Randall >=20 >=20 > . >
Hi all,

Was particularly interested in the pendulum hinge; but, the photos don= 't seem

to totally show exactly how they maintain position or their contact sh= ape or the adjacent

"supports" they rest on. Indeed....the supports may we= ll be glass but its just a

guess, or, they are made of angled metal? I see no grooves in th= e supports to keep

the hinge in its centralized placement. Perhaps the hinge contac= t points are simply

like ball bearings?

Has anybody seem the April issue of Popular Science magazine= , where it

"hopefully" shows the seismometer"? If so, i= s it like the referenced

web page below?

Take care, Meredith Lamb

On 9/14/05, = Larry Cochrane <lcochran= e@..............> wrote:

FYI.. -Larry
------------= ---------------------------------------------------------------
Hi Larry= .
   With all the attention given to hurricane Katrina (and now= , increasingly of Ophelia
as it is battering the Carolinas) you may be i= nterested in my latest paper, titled
"Hurricanes and Earth hum"= ;, online at=20 http://arxiv.org/html/phy= sics/0509103
      The records for thi= s paper were taken with my 'modernized conventional
pendulum', some pict= ures of which are posted to this arxiv site.  The pendulum was
featured in the April issue of the Popular Science article titled "= ;Affordable
earthquake detector", concerned with last year's tsunam= i.
   Feel free to mention this research on the PSN mailing li= st if you so choose.
Thanks for your interest and best regards,
  Randall

.

Subject: Re: Very Simple Sensor From: james fisher kd6iwd@......... Date: Sat, 17 Sep 2005 11:58:13 -0700 (PDT) Hi everybody, I have an experimental seismic sensor I would like to donate for testing. It is comprised of a voltmeter movement modified so that it can be coupled to a outside mass for seismic sensing. Will donate it to someone who will test it in a seismic system and post results. Best Regards Jim kd6iwd@......... --- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: ChrisAtUpw@....... Date: Sat, 17 Sep 2005 15:07:55 EDT In a message dated 17/09/05, kd6iwd@......... writes: > Hi everybody, I have an experimental seismic sensor I would like to donate > for testing. It is comprised of a voltmeter movement modified so that it can > be coupled > to a outside mass for seismic sensing. Will donate it to someone who will > Hi Jim, Does the meter have a torsion suspension or does it have needle bearings? Regards, Chris Chapman In a message=20= dated 17/09/05, kd6iwd@......... writes:

Hi everybody, I have an exp= erimental seismic sensor I would like to donate for testing. It is comprised= of a voltmeter movement modified so that it can be coupled
to a outside mass for seismic sensing. Will donate it to someone who wil= l test it in a seismic system and post results.

Hi Jim,

      Does the meter have a torsion suspe= nsion or does it have needle bearings?

      Regards,

      Chris Chapman Subject: Fwd: [Fwd: additional hurricane studies] From: meredith lamb paleoartifact@......... Date: Sat, 17 Sep 2005 13:59:05 -0600 ---------- Forwarded message ---------- From: meredith lamb Date: Sep 17, 2005 1:56 PM Subject: Re: [Fwd: additional hurricane studies] To: "ChrisAtUpw@......." Hi Chris, Thanks for the information!!! It is a interesting approach for a hanging= =20 pendulum (for us amateurs; they could also be called "S-G's" of course. It= =20 would seem to allow for a very tight capactive sensor spacing without most= =20 of the non-sensing possible sideways spurious motion (assuming a rigid boom= )=20 as opposed to using like acouple strips of flexible thin aluminum, brass=20 etc., to suspend a boom/mass of most current models I've seen. Of course,= =20 such a hinge could be fairly easily adopted for two wire pickup coils or=20 with more difficulty for using 3 wire Hall sensors also.=20 Of course aside from the exotic approache/s discussed, and for the majorit= y=20 of us, one could consider the ball bearing approach, where the top of the= =20 boom has a "T" section, and two ball bearings are affixed underneath and on= =20 the ends of the extension "arms" of the "T" boom top framed used, and in=20 contact with acouple plain and level and nearby adjacent flat surfaces.=20 Aside from the electrical contact problem, one could run a wire, or=20 insulated wires from atop the boom via flexible small diameter gauge wire/s= =20 in spring like coil shapes for minimum physical influence. It would=20 certainly alleviate alot of construction detail hassles via thin flat metal= =20 strips of older hinge designs. From what I hear, the ball bearing approach= =20 with horizontals works quite well....so....why not with a hanging pendulum?= =20 Here, the weight of the boom/mass can be quite abit larger of course. The= =20 boom/mass would get thrown off with a strong local quake I suppose, but mos= t=20 instruments would also be useless in the kind of event circumstance also.= =20 Another approach could be intrinsically with also two ball bearings on a= =20 frame which rests atop a single larger center support, but where it is in a= =20 "U" shape over and separated from the support (with the ends of the "U"=20 downward). Now....one would have two "booms", with which to entertain using= =20 sensors and or dampening, and/or=20 feedback to one side or the other. One could still call it a "hanging gate"= ,=20 but with the vertical (hanging) slant of course. For example: Acouple glued= =20 end to end bricks (the center support), should give enough height for a=20 natural oscillating period of one second, but with a very sensitive sensor= =20 one should pick up long period waves easily...not physically pretty, but it= =20 could work well I'd think. Round brass/copper and compression "T" fittings= =20 come to mind here. The two ball bearings would likely have to be centered o= n=20 the diameter/width on the cross support for correct vertical balance, but= =20 their is likely other mechanical ways of means of correcting this, if its= =20 shown to be a problem.=20 Interesting and fun stuff...it kind of makes one want to run out and start= =20 building doesn't it.... Take care, Meredith Lamb=20 On 9/16/05, ChrisAtUpw@....... wrote:=20 >=20 > Was particularly interested in the pendulum hinge; but, the photos don't= =20 > seem=20 > to totally show exactly how they maintain position or their contact shape= =20 > or the adjacent "supports" they rest on.=20 >=20 > Hi Meredith,=20 >=20 > The suspension is vertical sapphire phonograph needles on sapphire plates= ..=20 > He has had problems with the tips digging in (why am I not surprised?), s= o=20 > don't try copying it. I don't know why he hasn't used sapphire spheres. T= hey=20 > are available.=20 >=20 > I suggested tungsten carbide crossed cylinders, but he wasn't very=20 > receptive to the idea. You just buy drill bits and cut off the shank end!= =20 > Latest idea is to use tungsten carbide spheres from roller ball pens on= =20 > martensitic stainless steel. I think that he is heading for trouble. The= =20 > 'balls' are far too tiny and are not actually spherical, but he wants it = to=20 > be *'cheap'*. Stainless steel is only stainless because it oxidises=20 > immediately to give a protective film. Stressing the surface is likely to= =20 > increase the oxide thickness and give an insulating layer, which is exact= ly=20 > what he doesn't want.=20 >=20 > My philosophy is that it must work and work well. You sort out the cost= =20 > later.=20 >=20 > Regards,=20 >=20 > Chris

---------- Forwarded message ----------
From: meredith lamb <paleoartifact@.........>
Date: Sep = 17, 2005 1:56 PM
Subject: Re: [Fwd: additional hurricane studies]
To: "ChrisAtUpw@......." <ChrisAtUpw@.......>

Hi Chris,

Thanks for the information!!! It is a interesting approach for a= hanging pendulum (for us amateurs; they could also be called "S-G's&q= uot; of course. It would seem to allow for a very tight capactive sen= sor spacing without most of the non-sensing possible sideways spurious moti= on (assuming a rigid boom) as opposed to using like acouple strips of flexi= ble thin aluminum, brass etc., to suspend a boom/mass of most current model= s I've seen. Of course, such a hinge could be fairly easily adopted f= or two wire pickup coils or with more difficulty for using 3 wire Hall sens= ors also.=20

Of course aside from the exotic approache/s discussed, and for the maj= ority of us, one could consider the ball bearing approach, where the top of= the boom has a "T" section, and two ball bearings are affixed un= derneath and on the ends of the extension "arms" of the "T&q= uot; boom top framed used, and in contact with acouple plain and level and = nearby adjacent flat surfaces. Aside from the electrical contact prob= lem, one could run a wire, or insulated wires from atop the boom via flexib= le small diameter gauge wire/s in spring like coil shapes for minimum physi= cal influence. It would certainly alleviate alot of construction deta= il hassles via thin flat metal strips of older hinge designs. From wh= at I hear, the ball bearing approach with horizontals works quite well....s= o....why not with a hanging pendulum? Here, the weight of the bo= om/mass can be quite abit larger of course. The boom/mass would get t= hrown off with a strong local quake I suppose, but most instruments would a= lso be useless in the kind of event circumstance also.=20

Another approach could be intrinsically with also two ball bearings on= a frame which rests atop a single larger center support, but where it is i= n a "U" shape over and separated from the support (with the ends = of the "U" downward). Now....one would have two "booms= ", with which to entertain using sensors and or dampening, and/or=20

feedback to one side or the other. One could still call it a &qu= ot;hanging gate", but with the vertical (hanging) slant of course.&nbs= p; For example: Acouple glued end to end bricks (the center support), = should give enough height for a natural oscillating period of one seco= nd, but with a very sensitive sensor one should pick up long period wa= ves easily...not physically pretty, but it could work well I'd think. = Round brass/copper and compression "T" fittings come to mind her= e. The two ball bearings would likely have to be centered on the diam= eter/width on the cross support for correct vertical balance, but their is = likely other mechanical ways of means of correcting this, if its shown to b= e a problem.=20

Interesting and fun stuff...it kind of makes one want to run out and s= tart building doesn't it....

Take care, Meredith Lamb

On 9/16/05, = ChrisAtUpw@....... < ChrisAtUpw@.......> wrote:=20
<= font size=3D"2">Was particularly interested in the pendulum hinge; bu= t, the photos don't seem=20
to totally show exactly how they maintain position or their contact sha= pe or the adjacent "supports" they rest on.

Hi Mer= edith,

      The suspension is vertic= al sapphire phonograph needles on sapphire plates. He has had problems with= the tips digging in (why am I not surprised?), so don't try copying it. I = don't know why he hasn't used sapphire spheres. They are available.=20

      I suggested tungsten carbide cr= ossed cylinders, but he wasn't very receptive to the idea. You just buy dri= ll bits and cut off the shank end! Latest idea is to use tungsten carbide s= pheres from roller ball pens on martensitic stainless steel. I think that h= e is heading for trouble. The 'balls' are far too tiny and are not actually= spherical, but he wants it to be=20 'cheap'. Stainless steel is only stainless because it oxidises immed= iately to give a protective film. Stressing the surface is likely to increa= se the oxide thickness and give an insulating layer, which is exactly what = he doesn't want.=20

      My philosophy is that it must w= ork and work well. You sort out the cost later.

   &= nbsp;  Regards,

      Chris=

Subject: Re: [Fwd: additional hurricane studies] From: "Geoff" gmvoeth@........... Date: Sat, 17 Sep 2005 15:33:41 -0700 of us, one could consider the ball bearing approach, where the top of the boom has a "T" section, and two ball bearings are affixed underneath and on I have often wondered if a graphite bearing surface might work since graphite is a lubricant. Just have to be careful about loading because graphite is relatively weak I should imagine. Sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: james fisher kd6iwd@......... Date: Mon, 19 Sep 2005 12:59:22 -0700 (PDT) Hi Chris, The meter has small bearings that typically are something like synthetic ruby with a needle point pivot. I think that the very high intensity magnetic field in a meter movement will make a good seismometer if coupled to a mass to give it sensitivity. Also- I did an experiment in which I hooked two identical meter movements together, with the cover off of one, I then moved the needle. The induced current in the meter coil was sufficient to move the second meter without any amplification at all. This suggests that the efficiency is high. Best Regards Jim __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: ChrisAtUpw@....... Date: Mon, 19 Sep 2005 18:26:35 EDT In a message dated 19/09/05, kd6iwd@......... writes: > Hi Chris, The meter has small bearings that typically are something like > synthetic ruby with a needle point pivot. I think that the very high intensity > magnetic > field in a meter movement will make a good seismometer if coupled to a mass > to give it sensitivity. Hi Jim, They could make OK accelerometers for general purpose use, but they are very unlikely to be of much use as a seismometer. Only the torsion suspension types have the zero bearing friction necessary. Meter movements are often quite highly damped. 'Observable' seismic signals may be movements of just a few tens of nano metres, upwards. The ocean background signals with a period of about 6 sec, which are seen as quite large in seismic terms, are movements of only a few microns, typically about 2. Incidentally, moving coil meters are fairly expensive items in these days of LCD and LED displays. You can make OK cheap seismic sensors using the 41 / 50 mm dia piezo sounder disks and a weight, but you need a very high impedance low noise amplifier, maybe 100 M Ohms input. Regards, Chris Chapman In a message=20= dated 19/09/05, kd6iwd@......... writes:

Hi Chris, The meter has sma= ll bearings that typically are something like synthetic ruby with a needle p= oint pivot. I think that the very high intensity magnetic
field in a meter movement will make a good seismometer if coupled to a m= ass to give it sensitivity.

Hi Jim,

      They could make OK accelerometers f= or general purpose use, but they are very unlikely to be of much use as a se= ismometer. Only the torsion suspension types have the zero bearing friction=20= necessary. Meter movements are often quite highly damped. 'Observable' seism= ic signals may be movements of just a few tens of nano metres, upwards. The=20= ocean background signals with a period of about 6 sec, which are seen as qui= te large in seismic terms, are movements of only a few microns, typically ab= out 2. Incidentally, moving coil meters are fairly expensive items in these=20= days of LCD and LED displays.

      You can make OK cheap seismic senso= rs using the 41 / 50 mm dia piezo sounder disks and a weight, but you need a= very high impedance low noise amplifier, maybe 100 M Ohms input.

      Regards,

      Chris Chapman Subject: Re: New article from Silicon chip magazine on buildind a seismograph. From: "Edward Ianni" edwianni1@........... Date: Mon, 19 Sep 2005 21:05:04 -0400 Subject: New article from Silicon chip magazine on buildind a = seismograph.=20 http://www.siliconchip.com.au/cms/A_105119/article.html
Subject: New article from Silicon chip magazine on buildind = a=20 seismograph.

http://www.siliconchip.com.au/cms/A_105119/article.html

Subject: Re: New article from Silicon chip magazine on buildind a seismograph. From: "Geoff" gmvoeth@........... Date: Mon, 19 Sep 2005 22:27:07 -0700 I think someone is not an amateur here they are trying to capitalize. This magazine article requires you to subscribe for a substantial fee. sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: "Geoff" gmvoeth@........... Date: Mon, 19 Sep 2005 22:59:20 -0700 > You can make OK cheap seismic sensors using the 41 / 50 mm dia piezo > sounder disks and a weight, but you need a very high impedance low noise > amplifier, maybe 100 M Ohms input. > > Regards, > > Chris Chapman > If you were to suspend most of the weight of a 4 or 5LB mass on the end of a spring and then take up the last one ounce of weight upon such a Piezo sounder disk would that improve the signal receiving qualities any over just placing a one ounce weight on it ? A strong signal on such a device would probably ruin it. Sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: ChrisAtUpw@....... Date: Tue, 20 Sep 2005 07:46:25 EDT In a message dated 20/09/05, gmvoeth@........... writes: > > You can make OK cheap seismic sensors using the 41 / 50 mm dia > piezo > > sounder disks and a weight, but you need a very high impedance low noise > > amplifier, maybe 100 M Ohms input. > > If you were to suspend most of the weight of a 4 or 5LB mass on the end of a > spring and then take up the last one ounce of weight upon such a Piezo > sounder disk would that improve the signal receiving qualities any over just > placing a one ounce weight on it ? > A strong signal on such a device would probably ruin it. Hi Geoff, Apart from any danger of breaking the device, you would be limited in period by the mass and the force constant of the spring. These tend to come out at about a second max for simple spring + weight systems. You would also have to provide effective damping for the system. With the simple Piezo Disk + Seismic Mass, the natural resonant frequency is about 170 Hz, so you are operating it as a simple force in / voltage out accelerometer well below resonance. You can filter out any impulse responses at the natural frequency, or you can provide sorbothane or magnetic damping. The lower roll off is due to the RC time constant of the disk capacity and the input impedance of the opamp. With a simple piezo system, I get about 5x the voltage output of a 380 Ohm 4.5 Hz geophone. You do have to thermally screen the device to prevent drifts due to temperature changes and you need a couple of low leakage diodes, FDH300 or 1N3595, across the input to protect the opamp. Loaded Piezo disks will happily generate many 10s of Volts if knocked, quite enough to damage the input protection circuit in an opamp. Zeners have relatively high leakage currents in the microamp region and are likely to limit the max RC response time. Regards, Chris Chapman In a message=20= dated 20/09/05, gmvoeth@........... writes:

>    &nbs= p;  You can make OK cheap seismic sensors using the 41 / 50 mm dia= piezo=20
> sounder disks and a weight, but you need a very high impedance low=20= noise=20
> amplifier, maybe 100 M Ohms input.

If you were to suspend most of the weight of a 4 or 5LB mass on the end=20= of a spring and then take up the last one ounce of weight upon such a Piezo=20= sounder disk would that improve the signal receiving qualities any over just= placing a one ounce weight on it ?
A strong signal on such a device would probably ruin it.

Hi Geoff,

      Apart from any danger of breaking t= he device, you would be limited in period by the mass and the force constant= of the spring. These tend to come out at about a second max for simple spri= ng + weight systems. You would also have to provide effective damping for th= e system.
      With the simple Piezo Disk + Seismi= c Mass, the natural resonant frequency is about 170 Hz, so you are operating= it as a simple force in / voltage out accelerometer well below resonance. Y= ou can filter out any impulse responses at the natural frequency, or you can= provide sorbothane or magnetic damping. The lower roll off is due to the RC= time constant of the disk capacity and the input impedance of the opamp. Wi= th a simple piezo system, I get about 5x the voltage output of a 380 Ohm 4.5= Hz geophone.=20
      You do have to thermally screen the= device to prevent drifts due to temperature changes and you need a couple o= f low leakage diodes, FDH300 or 1N3595, across the input to protect the opam= p. Loaded Piezo disks will happily generate many 10s of Volts if knocked, qu= ite enough to damage the input protection circuit in an opamp. Zeners have r= elatively high leakage currents in the microamp region and are likely to lim= it the max RC response time.

      Regards,

      Chris Chapman Subject: Re: Concerning article from Silicon chip magazine on buildind a From: "Edward Ianni" edwianni1@........... Date: Tue, 20 Sep 2005 09:16:28 -0400 A few months ago I contacted the magazine (SC) and asked if they ever = had written an article on building a seismograph. They replied that they = hadn't, but they would look into it. Yesterday I received an email from = them, showing they had gotten around to doing it. Ed.

A few months ago I contacted the = magazine (SC)=20 and asked if they ever had written an article on building a = seismograph.=20 They replied that they hadn't, but they would look into it. = Yesterday I=20 received an email from them, showing they had gotten around = to doing=20 it. Ed.

Subject: Re: New article from Silicon chip magazine on building a From: John or Jan Lahr JohnJan@........ Date: Tue, 20 Sep 2005 07:12:46 -0700 I spent the $8.80 to see what the article would be. It's not really too advanced, but it would be nice to get the author to participate with the PSN and share his experiences freely with the amateur community. The images were particularly disappointing because larger images were not provided after purchasing the article. Cheers, John At 10:27 PM 9/19/2005, you wrote: >I think someone is not an amateur here >they are trying to capitalize. >This magazine article requires you to subscribe for >a substantial fee. > >sincerely; >gmvoeth >__________________________________________________________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Concerning article from Silicon chip magazine on building From: John or Jan Lahr JohnJan@........ Date: Tue, 20 Sep 2005 08:11:15 -0700 I took a look this morning, and this time the full article, including larger images, came through to my computer! I'm not sure why. The URL yesterday after I paid was: http://www.siliconchip.com.au/cms/A_105119/printArticle.html while today it's http://www.siliconchip.com.au/cms/A_105119/article.html. In any case, the larger figures do document the design. Cheers, John At 07:13 AM 9/20/2005, you wrote: >I spent the $8.80 to see what the article would be. It's not really >too advanced, but it >would be nice to get the author to participate with the PSN and >share his experiences >freely with the amateur community. The images were particularly >disappointing >because larger images were not provided after purchasing the article. > >Cheers, >John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: "Geoff" gmvoeth@........... Date: Tue, 20 Sep 2005 08:14:49 -0700 Hello Chris; Can you tell me what the roll off rate is for the Piezo element... Is it 40db per decade like I understand is true for magnet coil velocity systems ? Sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: ChrisAtUpw@....... Date: Tue, 20 Sep 2005 13:25:13 EDT In a message dated 20/09/05, gmvoeth@........... writes: > Can you tell me what the roll off rate is for the Piezo element... Is it > 40db per decade like I understand is true for magnet coil velocity systems ? Hi Geoff, As far as I know, it is an ordinary acceleration response, which is 20 dB / decade above the RC roll off, which is why I use such a high input impedance amplifier to give the maximum period. The magnet / coil velocity systems are 40 dB / decade, since you have the force / deflection of 20 dB / decade and the induced voltage / velocity giving another 20 dB / decade. Regards, Chris Chapman In a message=20= dated 20/09/05, gmvoeth@........... writes:

Can you tell me what the ro= ll off rate is for the Piezo element... Is it 40db per decade like I underst= and is true for magnet coil velocity systems ?

Hi Geoff,

      As far as I know, it is an ordinary= acceleration response, which is 20 dB / decade above the RC roll off, which= is why I use such a high input impedance amplifier to give the maximum peri= od.
      The magnet / coil velocity systems=20= are 40 dB / decade, since you have the force / deflection of 20 dB / decade=20= and the induced voltage / velocity giving another 20 dB / decade.

      Regards,

      Chris Chapman Subject: Re: Printer friendly / Concerning article from Silicon chip magazine on building a seismograph. From: "Erich Kern" efkern@............. Date: Tue, 20 Sep 2005 10:28:59 -0700 John, The URL yesterday was the printer friendly version which usually has reduced graphic content or none at all. Notice the first URL is the same as the second one except for the addition of the word 'print'. The second URL is the full Monty with all the bells and whistles. Erich Kern ----- Original Message ----- From: "John or Jan Lahr" To: Sent: Tuesday, September 20, 2005 8:11 AM Subject: Re: Concerning article from Silicon chip magazine on building a seismograph. I took a look this morning, and this time the full article, including larger images, came through to my computer! I'm not sure why. The URL yesterday after I paid was: http://www.siliconchip.com.au/cms/A_105119/printArticle.html while today it's http://www.siliconchip.com.au/cms/A_105119/article.html. In any case, the larger figures do document the design. Cheers, John At 07:13 AM 9/20/2005, you wrote: >I spent the $8.80 to see what the article would be. It's not really >too advanced, but it >would be nice to get the author to participate with the PSN and >share his experiences >freely with the amateur community. The images were particularly >disappointing >because larger images were not provided after purchasing the article. > >Cheers, >John __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Concerning article from Silicon chip magazine on building a seismograph. From: ChrisAtUpw@....... Date: Tue, 20 Sep 2005 20:32:29 EDT Hi John, Have a look at http://science.uniserve.edu.au/school/Seismograph/menu.html and http://www.seismicity.segs.uwa.edu.au/welcome/seismic_monitoring/QuakeWatch Regards, Chris Chapman Hi John,

      Have a look at http://science.unise= rve.edu.au/school/Seismograph/menu.html=20
and http://www.seismicity.segs.uwa.edu.au/welcome/seismic_monitoring/Qua= keWatch

      Regards,

      Chris Chapman

Subject: Re: [Fwd: additional hurricane studies] From: meredith lamb paleoartifact@......... Date: Thu, 22 Sep 2005 12:03:46 -0600 Hi Chris, Aside from Mr. Randalls commercial pursuit and opinions with a conductive ball bearing and surfaces....for just a plain ball bearings (and non-conductive) that is resting on surfaces of carbide...I would like your judgement of a more desireable diameter size of ball bearings where they would support, say, a range of boom/mass (heavy weight) S-G's where they range from roughly 1 to 5 pounds? Have to admit that your "figure of eight" lead wires suggestion for a trial; kind of leaves me wondering more of how it is totally configured; and/or arranged for hook up to a S-G; as somehow = I can't quite grasp that aspect? All these past email messages on ball bearings did indeed inspire me to tr= y out a table top experiment using such along the material lines as you have suggested over time. The results I'am seeing are amazing, in as far as the free and undampened oscillation times before it visually decays from a lack of visual eyeball movement with a S-G type ball bearing setup; which essentially is a indication of friction or other restraints therein. My old 2 strip suspension hinge S-G had only about 35 minutes of free oscillation (no dampening or hookup wires); whereas, the experimental ball bearing hinge had slightly over 4 hours for = a same 2" mass offset for visual oscillation decay tests. Also, as you mentioned, one can indeed eddy curren= t dampen the mass even though the ball bearings are on a flat smooth level carbide surface. Very interesting successful test/s and educational results! I've put up a temporary web page with 3 pictures and some text of such for anyone interested: http://home.earthlink.net/~meredithlamb/ballbearinghinge.html Take care, Meredith Lamb* * On 9/17/05, ChrisAtUpw@....... wrote: > > In a message dated 17/09/05, paleoartifact@......... writes: > > Hi Meredith, > > Randall's capacitative sensors don't require a particularly small spacing= , > but they may be able to move +/-2.5 mm. Where this type of sensor really > wins over the standard S-G type is that there is no pneumatic air damping= . > He can also increase the sensitivity by adding more, but narrower, sensin= g > areas. He does not use any force feedback as far as I know - it can be > noisy. > > However, this approach does need a very high sensitivity. He complains > about the ocean background, but he hasn't filtered it out. He does not da= mp > the pendulum arguing that the frequencies in which he is interested are f= ar > below resonance. However, trying to sort out small slow digital signals f= rom > large fast noisy ones is not a method that I would choose. I prefer to > reduce the noise coming into the ADC as far as possible. > > I am quite happy with ball bearings so long as they are not too small. Th= e > curse of fine points and actual knife edges is that the blade material is > far too highly stressed. Adding fine wire loops is really not a problem s= o > long as you have the fine wire with polyurethane fusable coating. You jus= t > use a hot soldering iron and the coating varnish melts. > > I would be happier to try out two figure of 8 loops of fine wire or foil > around two horizontal circular rods. The gives a zero torque suspension a= nd > a well defined rotation axis. It can also be made resistant to large quak= es, > with a couple of dobs of epoxy. > > > Regards, > > Chris
Hi Chris,

Aside from Mr. Randalls commercial pursuit and opinions with a conduct= ive ball bearing and surfaces....for just a

plain ball bearings (and non-conductive) that is resting on surfaces o= f carbide...I would like your judgement of a

more desireable diameter size of ball bearings where they would suppor= t, say, a range of boom/mass (heavy

weight) S-G's where they range from roughly 1 to 5 pounds?

Have to admit that your "figure of eight" lead wires suggest= ion for a trial; kind of leaves me wondering more of how

it is totally configured; and/or arranged for hook up to a S-G; as som= ehow I can't quite grasp that aspect?

All these past email messages on ball bearings did indeed inspire me t= o try out a table top experiment using

such along the material lines as you have suggested over time. T= he results I'am seeing are amazing, in as far

as the free and undampened oscillation times before it visually decays= from a lack of visual eyeball movement

with a S-G type ball bearing setup; which essentially is a indication = of friction or other restraints therein. My old

2 strip suspension hinge S-G had only about 35 minutes of free os= cillation (no dampening or hookup wires);

whereas, the experimental ball bearing hinge had slightly over 4 hours= for a same 2" mass offset for visual

oscillation decay tests. Also, as you mentioned, one can indeed&= nbsp;eddy current dampen the mass even though

the ball bearings are on a flat smooth level carbide surface. Ve= ry interesting successful test/s and educational

results! I've put up a temporary web page with 3 pictures and so= me text of such for anyone interested:

http://home.earthlink.net/~meredithlamb/ballbearinghinge.html

Take care, Meredith Lamb

On 9/17/05, = ChrisAtUpw@....... <ChrisAtUpw@.......> wrote:
<= span class=3D"q">In a message dated 17/09/05, paleoartifact@......... writes:

Hi Meredith,

      Randall's cap= acitative sensors don't require a particularly small spacing, but they may = be able to move +/- 2.5 mm. Where this type of sensor really wins over the standard S-G type is= that there is no pneumatic air damping. He can also increase the sensitivi= ty by adding more, but narrower, sensing areas. He does not use any force f= eedback as far as I know - it can be noisy.=20

      However, this approach does nee= d a very high sensitivity. He complains about the ocean background, but he = hasn't filtered it out. He does not damp the pendulum arguing that the freq= uencies in which he is interested are far below resonance. However, trying = to sort out small slow digital signals from large fast noisy ones is not a = method that I would choose. I prefer to reduce the noise coming into the AD= C as far as possible.

      I = am quite happy with ball bearings so long as they are not too small. The cu= rse of fine points and actual knife edges is that the blade material is far= too highly stressed. Adding fine wire loops is really not a problem so lon= g as you have the fine wire with polyurethane fusable coating. You just use= a hot soldering iron and the coating varnish melts.

  &= nbsp;   I would be happier to try out two figure of 8 loops = of fine wire or foil around two horizontal circular rods. The gives a zero = torque suspension and a well defined rotation axis. It can also be made res= istant to large quakes, with a couple of dobs of epoxy.


     &nb= sp;Regards,

      Chris

Subject: Lehman sensor contruction From: triplederby100-propos@......... Date: Fri, 23 Sep 2005 07:16:07 -0700 (PDT) Hi. I am new to seismographs and am planning to build one with Lehman sensor. I have found a PDF document on PSN website that talks about constructing Lehman sensor. Can anyone comment on this document and if it is a good place to start building one with? I will also welcome any other advise on how to build a Lehman sensor. Thanks, Kaarigar ================== _______________________________________________________________ Triangle was an improvement over square wheel - it eliminated one bump per revolution. ─────────────────────────────────────────────────────────────── __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Lehman sensor contruction From: Richard Gagnon richg_1998@......... Date: Fri, 23 Sep 2005 07:23:52 -0700 (PDT) All I have read say the Lehman is pretty good. Do a search of all the messages in this group and you will find loads of information. Also do searches on the Net for Lehman, sensor, seismograph, combinations of these words for a start. Make yourself confortable because there is plenty of reading available. Cheers Richard --- triplederby100-propos@......... wrote: > Hi. > > I am new to seismographs and am planning to build one > with Lehman sensor. I have found a PDF document on PSN > website that talks about constructing Lehman sensor. > Can anyone comment on this document and if it is a > good place to start building one with? I will also > welcome any other advise on how to build a Lehman > sensor. > > Thanks, > > Kaarigar > ================== > > _______________________________________________________________ > Triangle was an improvement over square wheel - > it eliminated one bump per revolution. > ─────────────────────────────────────────────────────────────── > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Lehman sensor contruction From: ChrisAtUpw@....... Date: Fri, 23 Sep 2005 11:38:15 EDT In a message dated 23/09/05, triplederby100-propos@......... writes: > Hi. > I am new to seismographs and am planning to build one with Lehman sensor. I > have found a PDF document on PSN website that talks about constructing Lehman > sensor. Hi Kaarigar, Is this Kelly Knight's article? Can you say which Country / State you are in and give your rough age and some idea of your facilities and constructional skills please? Regards, Chris Chapman In a message=20= dated 23/09/05, triplederby100-propos@......... writes:

Hi.
I am new to seismographs and am planning to build one with Lehman sensor= .. I have found a PDF document on PSN website that talks about constructing L= ehman sensor.

Hi Kaarigar,

      Is this Kelly Knight's article?

      Can you say which Country / State y= ou are in and give your rough age and some idea of your facilities and const= ructional skills please?

      Regards,

      Chris Chapman

Subject: Re: Very Simple Sensor From: "Geoff" gmvoeth@........... Date: Fri, 23 Sep 2005 21:50:34 -0700 Mr. Chapman; Where do you recommend to one to obtain the Piezo elements and also the diodes ? Sincerely; gmvoeth __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Very Simple Sensor From: ChrisAtUpw@....... Date: Sat, 24 Sep 2005 01:22:31 EDT In a message dated 24/09/05, gmvoeth@........... writes: > Where do you recommend to one to obtain the Piezo elements and also > the diodes ? Hi Geoff, I haven't had time to search the US sites, but I know that they are available. Where have you tried? The only one that I am reasonably certain about is Newark-online, since I buy from them. I think that digikey also do them from memory and maybe mouser? You are looking for piezo disks, preferably no housings and certainly no electronics. The large 50 mm ones that I use are sold as piezo speakers. Kingstate K47-KPS100 or Projects Unlimited APS100. There are many manufacturers. Digikey keep the 1N3595 diodes and also some disks. Let us know what you can find. Regards, Chris Chapman In a message=20= dated 24/09/05, gmvoeth@........... writes:

Where do you recommend to o= ne to obtain the Piezo elements and also
the diodes ?

Hi Geoff,

      I haven't had time to search the US= sites, but I know that they are available. Where have you tried? The only o= ne that I am reasonably certain about is Newark-online, since I buy from the= m. I think that digikey also do them from memory and maybe mouser?
      You are looking for piezo disks, pr= eferably no housings and certainly no electronics. The large 50 mm ones that= I use are sold as piezo speakers. Kingstate K47-KPS100 or Projects Unlimite= d APS100. There are many manufacturers.=20
      Digikey keep the 1N3595 diodes and=20= also some disks. Let us know what you can find.

      Regards,

      Chris Chapman Subject: Haifa. Earthquake's prediction. From: Alexandr Yagodin midia@.............. Date: Sat, 24 Sep 2005 14:03:17 +0200 http://www.inauka.ru/blogs/article57139.html Best regards Alexandr
http://www.inauka.ru/blogs/article57139.html

Best regards
Alexandr

Subject: Re: Haifa. Earthquake's prediction. From: Mauro Mariotti mariotti@......... Date: Sat, 24 Sep 2005 13:30:14 +0200 thank you alexander but... anybody knows where find an english translation? At 14:03 24/09/2005, you wrote: >http://www.inauka.ru/blogs/article57139.html > >Best regards >Alexandr > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Haifa. Earthquake's prediction. From: Mark Robinson mark.robinson@............... Date: Sun, 25 Sep 2005 00:10:25 +1200 > At 14:03 24/09/2005, you wrote: >> http://www.inauka.ru/blogs/article57139.html >> >> >> Best regards >> Alexandr Mauro Mariotti wrote: > thank you alexander > but... > > anybody knows where find an english translation? http://world.altavista.com/babelfish/tr Note that it didn't work using firefox 1.0.7 under linux, but the same browser under windows 98SE was fine. A fine time to remind people using firefox before 1.0.7 that now is the time to upgrade due to a recently discovered vulnerability rated "extremely critical". regards all Mark __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ebay auction From: BOB BARNS royb1@........... Date: Mon, 26 Sep 2005 09:28:31 -0400 Hi gang, Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7549331565 ends Oct 2 I'm guessing that it is a stripchart recorder. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Doug Crice" dcrice@............ Date: Mon, 26 Sep 2005 06:48:13 -0700 This would be more properly called a drum recorder. I believe that this unit includes amplifiers suitable for direct connection to a = seismometer. There would also be a way to time events. These units were commonly used = for chasing aftershocks, volcanoes, and geothermal events. You load up a = dozen or so and go off to the site of an interesting earthquake, record the aftershocks, and find the fault plane. These systems have been replaced by solid-state digital systems, but = drum recorders are nice for display seismographs. You can watch the = earthquakes happen without resorting to a computer monitor. Doug Crice=20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of BOB BARNS Sent: Monday, September 26, 2005 6:29 AM To: psn mail Subject: ebay auction Hi gang, Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7549331565 ends Oct 2 I'm guessing that it is a stripchart recorder. Bob __________________________________________________________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Doug Crice" dcrice@............ Date: Mon, 26 Sep 2005 06:48:13 -0700 This would be more properly called a drum recorder. I believe that this unit includes amplifiers suitable for direct connection to a = seismometer. There would also be a way to time events. These units were commonly used = for chasing aftershocks, volcanoes, and geothermal events. You load up a = dozen or so and go off to the site of an interesting earthquake, record the aftershocks, and find the fault plane. These systems have been replaced by solid-state digital systems, but = drum recorders are nice for display seismographs. You can watch the = earthquakes happen without resorting to a computer monitor. Doug Crice=20 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... = On Behalf Of BOB BARNS Sent: Monday, September 26, 2005 6:29 AM To: psn mail Subject: ebay auction Hi gang, Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7549331565 ends Oct 2 I'm guessing that it is a stripchart recorder. Bob __________________________________________________________ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Jack Ivey" ivey@.......... Date: Mon, 26 Sep 2005 10:07:15 -0400 It's a portable Helicorder. Looks like it is the stylus=20 version rather than the pen version. This means you need to use=20 smoked paper or find the ink pen kit somewhere. It wants 2 sealed=20 12V batteries to run properly. You can set the speed of the=20 drum and line spacing and it has a wide range of input gains (down to=20 tens of mV/cm). Some of them also include time mark generators=20 that synchronize to WWV/WWVH and are wonder of early=20 microprocessor technology (1980?). I don't see the stylus itself, and the arm that the stylus attaches to looks like it has been bent and "unbent", but that shouldn't be a big problem. Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of BOB BARNS Sent: Monday, September 26, 2005 9:29 AM To: psn mail Subject: ebay auction Hi gang, Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7549331565 ends Oct 2 I'm guessing that it is a stripchart recorder. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: ebay auction From: "Jack Ivey" ivey@.......... Date: Mon, 26 Sep 2005 10:07:15 -0400 It's a portable Helicorder. Looks like it is the stylus=20 version rather than the pen version. This means you need to use=20 smoked paper or find the ink pen kit somewhere. It wants 2 sealed=20 12V batteries to run properly. You can set the speed of the=20 drum and line spacing and it has a wide range of input gains (down to=20 tens of mV/cm). Some of them also include time mark generators=20 that synchronize to WWV/WWVH and are wonder of early=20 microprocessor technology (1980?). I don't see the stylus itself, and the arm that the stylus attaches to looks like it has been bent and "unbent", but that shouldn't be a big problem. Jack -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of BOB BARNS Sent: Monday, September 26, 2005 9:29 AM To: psn mail Subject: ebay auction Hi gang, Teledyne Geotech Portacorder RV-320 Seismograph Item number: 7549331565 ends Oct 2 I'm guessing that it is a stripchart recorder. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction From: ChrisAtUpw@....... Date: Mon, 26 Sep 2005 12:12:07 EDT In a message dated 26/09/05, ivey@.......... writes: > It's a portable Helicorder. Looks like it is the stylus version rather > than the pen version. This means you need to use smoked paper or find the ink > pen kit somewhere. Hi there, It is quite easy to make a lamp with a pickle jar, a metal lid, some metal tube, a wick and paraffin, to smoke paper. You clip the paper tightly onto the drum and rotate the whole thing over the smoky flame, till you get an even, totally black cover. The presence of the metal backing drum stops the paper from catching fire. When the trace is complete, you very carefully remove the paper and SPRAY THE BACK SIDE OF THE PAPER with hair lacquer, so that it is wet right through. When this has dried, you can also spray the front of the trace. If you try to just spray the front of the trace, a lot of the carbon blows away and you get a blotchy, uneven result. You get a much higher resolution from this type of trace than from an ink pen. Regards, Chris Chapman In a message=20= dated 26/09/05, ivey@.......... writes:

It's a portable Helicorder.= Looks like it is the stylus version rather than the pen version. &nbs= p;This means you need to use smoked paper or find the ink pen kit somewhere.=

Hi there,

      It is quite easy to make a lamp wit= h a pickle jar, a metal lid, some metal tube, a wick and paraffin, to smoke=20= paper. You clip the paper tightly onto the drum and rotate the whole thing o= ver the smoky flame, till you get an even, totally black cover. The presence= of the metal backing drum stops the paper from catching fire. When the trac= e is complete, you very carefully remove the paper and SPRAY THE BACK SIDE O= F THE PAPER with hair lacquer, so that it is wet right through. When this ha= s dried, you can also spray the front of the trace. If you try to just spray= the front of the trace, a lot of the carbon blows away and you get a blotch= y, uneven result. You get a much higher resolution from this type of trace t= han from an ink pen.

      Regards,

      Chris Chapman Subject: Re: Very Simple Sensor From: ChrisAtUpw@....... Date: Mon, 26 Sep 2005 15:24:10 EDT In a message dated 24/09/05, gmvoeth@........... writes: > Where do you recommend to one to obtain the Piezo elements and also > the diodes ? Hi there, Piezo elements for making seismic sensors www.digikey.com have the 1N3595 diodes and PZT disks See also p1421 for piezo elements - 102-1170-ND 44mm OD, 70 nF at $1.62 www.mouser.com also have the 1N3595 diodes and PZT disks See p1270 for piezo elements 665-KBI-4406 44mm OD, 70nF at $1.69 665-APS-100 50mm OD, 65nF at $2.05 Regards, Chris Chapman In a message=20= dated 24/09/05, gmvoeth@........... writes:

Where do you recommend to o= ne to obtain the Piezo elements and also
the diodes ?

Hi there,

      Piezo elements for making seismic s= ensors=20

      www.digikey.com have the 1N3595 dio= des and PZT disks=20
      See also p1421 for piezo elements -= 102-1170-ND 44mm OD, 70 nF at $1.62=20

      www.mouser.com also have the 1N3595= diodes and PZT disks
      See p1270 for piezo elements 665-KB= I-4406 44mm OD, 70nF at $1.69
      665-APS-100 50mm OD, 65nF at $2.05

      Regards,

      Chris Chapman Subject: Re: ebay auction From: Kevin McCue asc@............... Date: Tue, 27 Sep 2005 08:27:54 +1000 Chris No need to spray the back. Just use hair spray for oily hair - it=20 contains no oil particles which cause the blotchy look and can obscure=20= the first arrival. Cheers Kevin On 27/09/2005, at 2:12 AM, ChrisAtUpw@....... wrote: > In a message dated 26/09/05, ivey@.......... writes: > > > > Hi there, > > =A0=A0=A0=A0=A0=A0It is quite easy to make a lamp with a pickle jar, = a metal lid,=20 > some metal tube, a wick and paraffin, to smoke paper. You clip the=20 > paper tightly onto the drum and rotate the whole thing over the smoky=20= > flame, till you get an even, totally black cover. The presence of the=20= > metal backing drum stops the paper from catching fire. When the trace=20= > is complete, you very carefully remove the paper and SPRAY THE BACK=20 > SIDE OF THE PAPER with hair lacquer, so that it is wet right through.=20= > When this has dried, you can also spray the front of the trace. If you=20= > try to just spray the front of the trace, a lot of the carbon blows=20 > away and you get a blotchy, uneven result. You get a much higher=20 > resolution from this type of trace than from an ink pen. > > =A0=A0=A0=A0=A0=A0Regards, > > =A0=A0=A0=A0=A0=A0Chris Chapman Kevin McCue Director Australian Seismological Centre PO Box 324 Jamison Centre ACT 2614 Australia ph: 61 (0)2 6251 1291 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction - fixing smoked traces From: ChrisAtUpw@....... Date: Mon, 26 Sep 2005 20:43:14 EDT In a message dated 26/09/05, asc@............... writes: > Chris > No need to spray the back. Just use hair spray for oily hair - it contains > no oil particles which cause the blotchy look and can obscure the first > arrival. Hi Kevin, Thanks for the comment! The blotchy look on my early gliding barograph traces came from actual blast / droplet removal of areas of carbon. The coating is only lightly attached and the adhesion can be somewhat variable. Sure, with practice I learnt to lightly smoke the paper just the right amount and later spray the coat from a considerable distance to fix it to get a nice clear trace, but this took quite a bit of trial and oops. I later found it much easier to spray / soak just the back of the paper and get a 100% reliable good trace - there is no skill to learn and it uses less hair spray! You can also use other types of spray lacquer. The paper also becomes more translucent making the trace easier to read. Why do things the hard way? Regards, Chris Chapman In a message=20= dated 26/09/05, asc@............... writes:

Chris
No need to spray the back. Just use hair spray for oily hair - it contai= ns no oil particles which cause the blotchy look and can obscure the f= irst arrival.

Hi Kevin,

      Thanks for the comment! The blotchy= look on my early gliding barograph traces came from actual blast / droplet=20= removal of areas of carbon. The coating is only lightly attached and the adh= esion can be somewhat variable. Sure, with practice I learnt to lightly smok= e the paper just the right amount and later spray the coat from a considerab= le distance to fix it to get a nice clear trace, but this took quite a bit o= f trial and oops.=20
      I later found it much easier to spr= ay / soak just the back of the paper and get a 100% reliable good trace - th= ere is no skill to learn and it uses less hair spray! You can also use other= types of spray lacquer. The paper also becomes more translucent making the=20= trace easier to read. Why do things the hard way?

      Regards,

      Chris Chapman Subject: RE: ebay auction - fixing smoked traces From: "Kareem at HeyJooJoo" system98765@............. Date: Mon, 26 Sep 2005 18:48:15 -0700 I believe that you can just use paper and ink to avoid the mess of smoked records. Leave that for the BBQ. By the way, can the pen housings/mechanisms be exchanged for a different type? I have a pen that seems to clog - I believe that this is the older type and was wondering if there's a newer better type of pen. The system is a PS2 recorder by Kinemetrics. Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Monday, September 26, 2005 5:43 PM To: asc@................ psn-l@.............. Subject: Re: ebay auction - fixing smoked traces In a message dated 26/09/05, asc@............... writes: Chris No need to spray the back. Just use hair spray for oily hair - it contains no oil particles which cause the blotchy look and can obscure the first arrival. Hi Kevin, Thanks for the comment! The blotchy look on my early gliding barograph traces came from actual blast / droplet removal of areas of carbon. The coating is only lightly attached and the adhesion can be somewhat variable. Sure, with practice I learnt to lightly smoke the paper just the right amount and later spray the coat from a considerable distance to fix it to get a nice clear trace, but this took quite a bit of trial and oops. I later found it much easier to spray / soak just the back of the paper and get a 100% reliable good trace - there is no skill to learn and it uses less hair spray! You can also use other types of spray lacquer. The paper also becomes more translucent making the trace easier to read. Why do things the hard way? Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction - fixing smoked traces From: ChrisAtUpw@....... Date: Mon, 26 Sep 2005 22:32:16 EDT In a message dated 27/09/05, system98765@............. writes: > By the way, can the pen housings/mechanisms be exchanged for a different > type? I have a pen that seems to clog - I believe that this is the older > type and was wondering if there's a newer better type of pen. The system is > a PS2 recorder by Kinemetrics. You have to use the right sort of recorder ink. When did you last clean out the pen? Some modern pens may be interchangeable, the old ones usually were not. Ask Kinemetrics? Regards, Chris Chapman In a message=20= dated 27/09/05, system98765@............. writes:

By the way, can the pen hou= sings/mechanisms be exchanged for a different
type? I have a pen that seems to clog - I believe that this is the older
type and was wondering if there's a newer better type of pen. The system= is
a PS2 recorder by Kinemetrics.

      You have to use the right sort of r= ecorder ink. When did you last clean out the pen? Some modern pens may be in= terchangeable, the old ones usually were not. Ask Kinemetrics?=20

      Regards,

      Chris Chapman Subject: RE: ebay auction - fixing smoked traces From: "Kareem at HeyJooJoo" system98765@............. Date: Mon, 26 Sep 2005 22:09:03 -0700 Yeah. Just yesterday, I sent them an email and haven't heard back yet. But after having communicated with them before, I wouldn't expect anything fruitful. They must be very busy down there in so. Cal. Kareem -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Monday, September 26, 2005 7:32 PM To: psn-l@.............. Subject: Re: ebay auction - fixing smoked traces In a message dated 27/09/05, system98765@............. writes: By the way, can the pen housings/mechanisms be exchanged for a different type? I have a pen that seems to clog - I believe that this is the older type and was wondering if there's a newer better type of pen. The system is a PS2 recorder by Kinemetrics. You have to use the right sort of recorder ink. When did you last clean out the pen? Some modern pens may be interchangeable, the old ones usually were not. Ask Kinemetrics? Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction - fixing smoked traces From: "James Hannon" jmhannon@......... Date: Tue, 27 Sep 105 07:22:14 CDT Artists use something called "fixative spray" to protect charcoal drawings. It might work better than hair spray. http://www.dickblick.com/zz217/11/ Jim Hannon ---------- Original Message ---------------------------------- From: ChrisAtUpw@....... Reply-To: psn-l@.............. Date: Mon, 26 Sep 2005 20:43:14 EDT >In a message dated 26/09/05, asc@............... writes: > >> Chris >> No need to spray the back. Just use hair spray for oily hair - it contains >> no oil particles which cause the blotchy look and can obscure the first >> arrival. > >Hi Kevin, > > Thanks for the comment! The blotchy look on my early gliding barograph >traces came from actual blast / droplet removal of areas of carbon. The >coating is only lightly attached and the adhesion can be somewhat variable. Sure, >with practice I learnt to lightly smoke the paper just the right amount and >later spray the coat from a considerable distance to fix it to get a nice clear >trace, but this took quite a bit of trial and oops. > I later found it much easier to spray / soak just the back of the >paper and get a 100% reliable good trace - there is no skill to learn and it uses >less hair spray! You can also use other types of spray lacquer. The paper also >becomes more translucent making the trace easier to read. Why do things the >hard way? > > Regards, > > Chris Chapman > > -- Jim Hannon http://www.fmtcs.com/web/jmhannon/ 42,11.90N,91,39.26W WB0TXL -- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ebay auction - fixing smoked traces From: ChrisAtUpw@....... Date: Tue, 27 Sep 2005 09:13:29 EDT In a message dated 27/09/05, jmhannon@......... writes: > Artists use something called "fixative spray" to protect charcoal drawings= ..=20 > It might work better than hair spray. >=20 >=20 Hi Jim, Thanks for the comment! I see from your reference to Windsor and=20 Newton that 21711-1001 Artists' Workable Fixative 400 ml List $9.15 =B7 S= ave 34%=20 Price $5.99 =20 How does that compare with a large can of hair spray for price and=20 availability in your part of the world? I suspect that AWF gives a fixative=20 glaze, but may be designed not to fully penetrate the paper. We use hair spr= ay in=20 gliding since it is the cheapest spray lacquer that we can buy and it works=20 fine. I also suspect that pilots may 'borrow' the hair spray from their wive= s!=20 Dual use.... Regards, Chris Chapman In a message=20= dated 27/09/05, jmhannon@......... writes:

Artists use something calle= d "fixative spray" to protect charcoal drawings. It might work better than h= air spray.

http://www.dickblick.com/zz217/11/

Hi Jim,

      Thanks for the comment! I see from=20= your reference to Windsor and Newton that 21711-1001 Artists' Workable Fi= xative 400 ml List $9.15 =B7 Save 34% Price $5.99 =20

      How does that compare with a large=20= can of hair spray for price and availability in your part of the world? I su= spect that AWF gives a fixative glaze, but may be designed not to fully pene= trate the paper. We use hair spray in gliding since it is the cheapest spray= lacquer that we can buy and it works fine. I also suspect that pilots may '= borrow' the hair spray from their wives! Dual use....

      Regards,

      Chris Chapman

Subject: ebay auction From: BOB BARNS royb1@........... Date: Tue, 27 Sep 2005 13:22:14 -0400 Hi gang, Seismograph Blasting Machine Item number: 7549647013 ends Oct 3 Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L)