Strain Gage Seismometer

[gmv]

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
No Emails, Possible Spams.

 

[John Jardine]

gmv <None@NoEmailsByThisRoute.123> wrote in message
news:MTneb.24$XP3.4644@news-west.eli.net...

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
No Emails, Possible Spams.

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

 

[Mark Fergerson]

gmv wrote:

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.

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.

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

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

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.

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

 

[Phil Hobbs]

gmv wrote:

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.

www.omega.com--about $50 for a package of 10.

Cheers,

Phil Hobbs

 

[gmv]

"Mark Fergerson" <nunya@biz.ness> typed in message news:3F7A765A.20107@biz.ness...

gmv wrote:
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.

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.

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

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

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.

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

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.

 

[John Fields]

On Tue, 07 Oct 2003 11:36:15 GMT, "gmv" <None@NoEmailsByThisRoute.123>
wrote:

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.

---
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.

--
John Fields