audio to gate using Arduino?

[Mickeyluv]

I want to generate a clean gate from a guitar signal using Arduino. The problem I see is the same as with some hardware comparator circuits where the harmonics cause problems and give multiple outputs on a dying note. Hysteresis, raising the comparator threshold or filtering helps, but reduces sensitivity (especially on higher notes). I think the coding would need to be more complicated than I first though.

Is there a sketch anywhere that does this? My searches have not provided any useful result.

[Grumble]

I wouldn’t use an Arduino for this, my strategy would be to first use a full wave rectifier, followed by a low pass filter and send that into a comparator.
Or for a more sophisticated solution:
https://modwiggler.com/forum/topic-109067.html&sid=fe4fbbda07d919a6f41853fc75d3a0a0

[blue hell]

But then .. in software you can do https://en.wikipedia.org/wiki/Analytic_signal .. which is expensive in analog hardware .. but prolly gives issues with harmonics (too).

And the analog hardware one will need some tweaking to get the release ok (when it needs to act fast).

Anyway ... envelope following is an interresting subject

[Mickeyluv]

The reason for thinking about Arduino is I'm already using one for my guitar interface and a software solution would keep the component count down. At the moment I'm using a MFOS circuit but ripple from the harmonics re-triggers my envelope generators. I can fix that, but then the response and sensitivity isn't too good

I found a Craig Anderton circuit that looks interesting in that it uses one half of a 571 as a 2:1 compressor and the other half as a full-wave rectifier. It gives an envelope and trigger output, but I want to breadboard it and feed a comparator directly with the 571 to give a gate. Use of a compressor is intriguing. I may be able to get away with just the 571 and an opamp + a few caps and resistors.