Jim Dossey wrote:

> I'm a programmer, not an EE, so I'm hoping someone here can point me in
> the right direction.  I'm currently working with a circuit that someone
> else designed, and now I'm writing software for it.  I can supply a
> schematic for this circuit, but I don't have it here in front of me.
> Basically, we have 2 DC signals and we need to take the difference
> between the 2, and amplify that difference by a factor of 10.  That
> input is then feed into one of the A/D converters on a 16C74A (thus the
> reason I am on this list).  The larger of the 2 signals is fed into the
> + input on an LMC6482, and the other is fed into the - input.  The
> problem is that when I graph the output signal, and a calculated value
> for S1-S2, they don't match.

What do you mean by "they don't match."?

> So my questions are these:
> 1. Is this a valid use of an op-amp?  Maybe we should have a multi-stage
> op-amp circuit instead of just using one.

I am not familiar with the LMC6482, but you have not specified the range of
voltage of the signals either.

> 2. Will an op-amp subtract 2 signals and then amplify that difference?

An Op-Amp can amplify the difference between two signals,

>
> 3. Is there a mailing list, web page, or book somewhere that will help
> me with op-amp design?
>
> Thanks,
> Jim Dossey

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