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

Neil Harper metadata at gmx.com
Fri Mar 22 00:14:33 CET 2024


On 2024-03-21 15:50, Rutger Vlek via Synth-diy wrote:> Dear list,
 >
 > while hobbying on an experimental design, I'm looking for a simple
 > analog circuit to give me the absolute value of the difference between
 > two signals (mathematically written as |a-b|).


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



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