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View Full Version : Summary re:strain gage conditioners and amplifiers



Chris Fritton
06-21-1994, 07:45 AM
Thanks to all who wrote in response to this inquiry posted last week.
A summary follows.


>In our lab we currently use the Vishay Strain Gage Conditioner and
>Amplifier (2100) System. Although this system has proven quite
>useful and dependable, it is bulky (by today's standards) and does
>not allow for the easy addition of filters.

>Does anyone have recent experience assembling a conditioner/
>amplifier system for use with strain gages and/or accelerometers?
>Does the Vishay Measurements Group still produce the gold standard
>in this type of instrumentation? What are the costs involved?

>On a related note, members of our lab have heard of a company that
>sells inexpensive, used electronic components (amplifiers, etc.).
>Does anyone know of such a company?

>Chris Fritton chris@bone.ortho.sunysb.edu
>Musculo-Skeletal Research Laboratory phone: (516) 444-2215
>Dept. of Orthopaedics T18-030 fax: (516) 444-7671
>S.U.N.Y. @ Stony Brook
>Stony Brook, NY 11794
__________________________________________________ ___________________

I use the plug-ins sold by Analog Devices for my National instruments
MIO board. I only have the strain gauge units, but they make 6 or 7
other units for things like current sources, thermocouples etc. They
are little black boxes about 2"x2"x.5" that plug into an external
backplane that is in turn wired into the A/D. Very convenient,
expandable. Cheap? Well, a few hundred per unit isn't cheap, but
they work well

Neil
--
N. Glossop, Ph.D.,
Toronto, Canada

neil@isgtec.com
__________________________________________________ ___________________

We have routinly used the Vishay conditioners and have found them to
be the best for the job. As for filters, you can allways digitaly
filter your data after the fact (assuming you sample fast enough).


For inexpensive used equipment, consider the folowing sources;

1. Bid Service 908-775-8300

2. The Source 800 722-2219

3. RGL Enterprise 602 996-0800

There may be others in your area, check the Thomas catalog.

Good luck,

Ed Wachtel
Bone Biomechanics Laboratory
UC Berkeley
Berkeley CA
94710
__________________________________________________ ___________________

The 2100 system is the mid- level of instrumentation available from
the Measurements Group. Although more expensive, I use the 2300
system in the lab course that I teach and it works very well. It has
an adjustable filter, auto balances and can be used for 1/4, 1/2 and
full bridge circuits. It is very, very important that you use very
well shielded cables (double shield) to obtain best results. They
also have a portable 4 module power rack for these units.

Another alternative would be a PC based a/d system for a laptop,
which may be more portable for your needs.

There are companies such as Analog Devices that sell strain gage
conditioning modules about the size of an ice cube. Just supply DC
power and they work very well for under $100. I use them too.

There are companies that sell used equipment. Try the Thomas
Register. I get their catalogs, but I trash them.

Good luck.

Mark Strauss

In preparation for the transfer of my E-mail account to
a new server, please update your records with my new address.
Send all future E-mail to MSTRAUSS@UIUC.EDU effective immediately.

__________________________________________________ ___________________
Mark G. Strauss, Ph.D.
Assistant Professor Rehabilitation Education and General Engineering
University of Illinois at Urbana-Champaign (VOICE) 217-333-4614
1207 South Oak St. (FAX) 217-333-0248
Champaign, IL 61820, USA (TDD) 217-333-1970
__________________________________________________ ___________________

Electro Rent Corporation sells used equipment, usually at a
substantial discount. Obviously, they also rent what they sell.

For New York, the phone number is 800-444-5284. The corporate offices
are in California at 818-787-2100.

Regards,
Ernie Wu
__________________________________________________ ___________________

After looking into the more expensive Measurements Groups'
Amp/Sig Cond, I found that Keithley MetraByte (800-348-0033)
produces a low cost one. I already had one of their A/D boards,
so the total cost was less than $1000 for an eight channel
system (EXP-GP). It is about 16" X 4" (not encased) and you
can piggy-back upto 8 of them (for 64 total channels) on one
A/D board.

Andy Karduna,
University of Pennsylvania
__________________________________________________ ___________________

I use the (expensive) 2310s which do have filters/filter options.

One alternative you might explore are 'instrumentation amps' and
'filter amps' on a chip (actually a hybrid) circut. These are
available from Analog Devices and Burr-Brown. With a relatively
small number of external components, you can make a nice little amp.

================================================== ===================
John F. Cummings
(John.Cummings@UC.EDU)
Noyes-Giannestras Biomechanics Laboratories
University of Cincinnati, ML0048
Cincinnati, OH 45221-0048