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Strain Gage Seismometer

Hello,

Does anyone know a good source for strain gages ?

I just want a strain gage and not the electronics everyone tries to sell with it.

I checked Google and could find only one supplier and the prices were all too high.

I am experimenting with the idea of using a strain gage as a seismic sensor and need a cheap source of parts. Used parts are A-OK.

I figure you might be able to simply support a mass upon a strain gage somehow then extract the signal down to the noise grass then look for seismic signals.

Any ideas here are welcome.

--
       Sincerely,
         gmv
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Reply to
gmv
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Don't know how many mil' surplus dumps you have there but an excellent source of soil seismometers is some kit made by Texas Instruments during the Vietnam war. It was used for detecting troop and vehicle movements at a couple of miles distance using buried sensors. Small satchel containing half a dozen seismic ground sensors and a battery operated amplifier/alarm unit. Picked up one for the equiv of $10! regards john

Reply to
John Jardine

That's bad, because the device output is picky about what it looks into, and the electronics are matched to the device to give whatever frequency response and bandwidth you need/are willing to live with.

So, you're working out of your beer budget, too?

What are you trying to sense exactly; mosquito farts, solar tides, or something in between? For fairly fast, fairly high-energy events, you might try ordinary piezo buzzer elements (good high frequency response) with some kind of weighted arm.

FTM, what sorts of electronics do you expect to use to see the output?

The thing will have some resonant frequency or other, and a bandwidth that may not be what you need.

For slower, low-energy events, piezos will have poor response and you'll have to amplify, which brings a load of other problems.

Ask a fuzzy question, get a fuzzy answer.

Mark L. Fergerson

Reply to
Mark Fergerson

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$50 for a package of 10.

Cheers,

Phil Hobbs

Reply to
Phil Hobbs

Nothing Fuzzy about my question. I am simply looking for a source of cheap strain guages. I might want to hang a 3.1 slug mass from such a device or possibly set the mass on top of the device. but with a 3.1 slug mass I must be able to measure a mere 1 grain or so of force caused by any accelerations. What I am looking to do here is to make a typical scale we are all familiar with in our bathrooms only this scale will be extremely sensitive down to the not so quiet seismic noise level. I have seriously thought of purchasing a typical electronic bathroom scale and trying to modify the innards to suit my needs. I suspect I might have to shoot for something much smaller than 3.1 slugs because ideally the mass and sensor should be contained in some kind of vacuum chamber. If things seem fuzzy to you it is only because you want more information than I am currently able to give.

--
       Sincerely,
         gmv
No Emails, Possible Spams.
Reply to
gmv 

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1 slug = 14.59 kg
3.1 slug = 45.23 kg = 99.5 lb ~ 1592 oz.
1 oz = 437.5 grains
1592 oz = 695500 grains,

so what you're trying to do is measure a change in force due to
acceleration of 1 part in 695,500, which is about 1.44ppm.  Tricky.
Reply to
John Fields

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