[sdiy] Simple circuit challenge: |a-b|

[Pete Hartman]

On Thu, Mar 21, 2024 at 6:32 PM Neil Harper via Synth-diy <
synth-diy at synth-diy.org> wrote:

> > can't you just put one signal into the inverting input of an op-amp and
> > the other signal into the non-inverting op-amp?
> >
> > if loading the signals are an issue, you can do op-amp buffers before it
> > and I think that configuration is called a "differential amp" and uses 3
> > op-amp cells. there's also dedicated IC's for diff amps, but they can be
> > $8-12 each and I think are only used when crazy precision is necessary -
> > maybe because it reduces the cumulative effects of resistor tolerance in
> > the 3 op-amp version?
> >
> >
> > --
> > /// Neil Harper
> > /// Every Wave is New Until it Breaks
>
> forget what I said, i didn't see the absolute value thing. i blame the
> internet for stealing my ability to fully read things.
>

I don't see why that's a bad idea, just put the rectification for abs()
after that op amp.
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