<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> </head> <body><div class="auto-created-dir-div" dir="auto" style="unicode-bidi: embed;"><div>Hello Rutger and List,</div><p><br></p><p>Here is my solution.</p><p><br></p><p>|a-b| = Max(a,b) - min(a,b).</p><p><br></p><p>If output offset is acceptable, we can omit D5, D6, and R7.<br></p><p>Impedance of inputs should be low. When one of inputs is open, output is a little distorted.</p><p><br></p><p>Sam HOSHUYAMA</p><p>Kawasaki, Japan.<br></p><br><blockquote style="margin: 0 auto;padding: 0 2.0em;border-left: 2.0px solid rgb(0,173,229);"><br><br>------ Original Message ------<br>差出人: "Rutger Vlek via Synth-diy" <<span class="wt_Email">synth-diy@synth-diy.org</span><span></span>><br>To: "SDIY List" <<span class="wt_Email">Synth-diy@synth-diy.org</span><span></span>><br>送信済み: 金曜日, 2024/3/22 04:50<br>件名: [sdiy] Simple circuit challenge: |a-b|<br><br><div dir="ltr">Dear list,<div><br></div><div>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|).</div><div><br></div><div>I already have a working circuit, but it's rather big for my needs. It uses an inverting opamp to invert signal A, followed by a bog-standard full wave precision rectifier circuit where -A and B are summed together and being rectified. The total is 3 opamps, 2 diodes and 9 resistors. As I need to repeat the circuit many times in the final application, I'm wondering: is there anything simpler that can do this?</div><div><br></div><div>Requirements:</div><div>- working across full audio range</div><div>- distortion as consequence of diode drops is no problem (might even be beneficial!)</div><div><br></div><div>Many thanks for any suggestions!</div><div><br></div><div>Regards,</div><div><br></div><div>Rutger</div></div> <hr>________________________________________________________<br> This is the Synth-diy mailing list<br> Submit email to: <span class="wt_Email"><span class="wt_Email">Synth-diy@synth-diy.org</span><span></span></span><span></span><br> View archive at: <a target="_blank" href="https://synth-diy.org/pipermail/synth-diy/">https://synth-diy.org/pipermail/synth-diy/</a><br> Check your settings at: <a target="_blank" href="https://synth-diy.org/mailman/listinfo/synth-diy">https://synth-diy.org/mailman/listinfo/synth-diy</a><br> Selling or trading? Use <span class="wt_Email"><span class="wt_Email">marketplace@synth-diy.org</span><span></span></span><span></span><br> </blockquote></div></body></html>