Use of Integrator/Differentiator block in a design

[familyortiz]

I was curious if these opamp configs are used in any common pedals. regards

[PRR]

> Integrator/Differentiator ... configs are used in any common pedals.

Not in pure form.

And FWIW, we can't build "pure" integrators or differentiators. One requires infinite gain at DC, the other infinite gain at infinite frequency.

Real integrators or differentiators go "flat" at the extremes. A practical integrator may have gain of 100,000 at DC to 1Hz, falling to 1 at 100KHz. Practical differentiators have zero gain at DC, may rise to gain of 100 at 1KHz, may run flat gain=100 for a bit, but always fall-down at some high frequency (they become integrators; everything integrates the fast stuff.)

However modified ints and diffs are everywhere. If an amp is flat 20Hz-20KHz and falling beyond, it is a differentiator from DC to 20Hz, then flat, then integrator past 20KHz. In fuzz pedals we often "differentiate" up to 500Hz (to lose the lows), distort, then "integrate" past 1KHz (to lose the shriek).

All tone controls can be understood as combinations of flat, int, and diff.

Power supply filtering is modified integration (though usually passive).

All interstage capacitor-coupling is a modified differentiator.

A very popular triangle-wave oscillator is a good integrator with a level detector to flop the input. A different connection is the key circuit in most digital meters.

The side-chain of a limiter is a modified integrator (it averages-out recent history to get an appropriate control signal).

Pitch-followers often start with integration to discount the harmonics.

One form of octave-down starts with a differentiator to sense zero-crossings, then toggles a /2 flip-flop to get a half-rate square-wave.

[familyortiz]

Thanks, the triangle wave oscillator is the type of example I was thinking of where you might flop an opamp integrator or differentiator block into a design. You could imagine using say, an integrator tap off an input signal to control the LFO frequency where you would end up with an LFO frequency that was dependent on how much sound you're making. i.e. pick frequency or intensity.