Aaron, what type of transducer do you have connected? Is it by any chance a
capacitive type? If so, you may have problems due to no dc path to ground
(or to a reference voltage) for your inputs of your amp.  Bias currents may
cause what you are seeing.

To separate the goat from the sheep, disconnect your transducer. Replace it
with a resistor network to get the approximate voltage your transducer
would have been generating.  Then turn on the amp and check it out.  If you
still have drift, it's the amp. If not, it's either the transducer or the
interaction of the transducer and the amp.

I'm assuming you have *carefully* checked all the wiring for your amp
circuit. And that you don't have large, leaky capacitors involved (perhaps
for signal filtering) that are causing the drift. And that you don't have
wires from the 'ducer to the amp that are unshielded and are 30 meters
long. And etc.

Good luck!
Tom M.

At 10:44 AM 7/26/02 -0400, you wrote:
>Hello all,
>          I'm using the classic instrumentational three opamp setup with
>all R = 100K except the one going between the two neg terminals which is
>1K.
>

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