[sdiy] Best & fastest envelope follower schematic.. anybody ?

Jean-Pierre Desrochers jpdesroc at oricom.ca
Wed Dec 15 16:05:39 CET 2021


Hi Tom,

>Harry Bissell's envelope follower is well thought of for its combination of speed and accuracy.
>https://modwiggler.com/forum/viewtopic.php?t=109067

This is a very clever project and neat design.
But still too much ‘lag’ on the falling edges incoming signal.
So far.. a PIC would do best with least components..
Hmmmm...
As usual.. Thank you for you good suggestion anyway !
JP


De : Tom Wiltshire <tom at electricdruid.net> 
Envoyé : 15 décembre 2021 04:08
À : Jean-Pierre Desrochers <jpdesroc at oricom.ca>
Cc : Synth-diy at synth-diy.org
Objet : Re: [sdiy] Best & fastest envelope follower schematic.. anybody ?

Hi JP,

Harry Bissell's envelope follower is well thought of for its combination of speed and accuracy.

https://modwiggler.com/forum/viewtopic.php?t=109067

It's a good circuit, but pretty complicated, especially for an effect pedal design. So like you, I thought "PIC!", and had a go at implementing it in firmware.

The round-robin three peaks detectors are easy enough. Doing the output filtering is more demanding on a chip with no multiply, but I managed it by being choosy about the filter coefficients and keeping things binary friendly. The end result was pretty good and used a little PIC to the maximum extent.

HTH,
Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================




On 15 Dec 2021, at 01:34, Jean-Pierre Desrochers <mailto:jpdesroc at oricom.ca> wrote:

Hi all,
I’m looking for a fast and accurate voltage follower circuit.
There are plenty of them on the web to build but they all
suffer of inaccuracy and lag on the final DC output (final stage of low pass to smooth off the incoming peaks).
The incoming voltage will be a varying 0 to +/-5v peak.
I thought about implementing a solution using a small PIC with ADC/DAC
but even if these micros are very cheap this solution would be overkill.. would it be ?
So far the available circuits have too much lag on their DC output.
(The envelope takes too much time to get back to zero after a fast incoming peak)
Any known & reliable circuits ?
JP
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