EDN article by H. Bissell...envelope follower

[keninverse]

couple of months ago there was an EDN article about pitch followers written by Harry Bissell.  I think it was something like using three different channels to find the peak from the original signal....
Anyone try this circuit out yet and have it interface with an LPF or anything?

[Mark Hammer]

http://www.ustomp.com/index.html?menu=2§ion=24

[keninverse]

do you happen to know how much voltage is produced at the end peak detect circuits (given a typical guitar signal)?

[R.G.]

I believe it will produce voltages equal to the peaks of the guitar signal unless you mess with gain or attenuation before the circuit. So the question really is - what is the peak levels one would expect from a guitar signal. That's going to depend heavily on the pickup. Single coils will give you 50-100mv peak right after the pick attack. Humbuckers will be twice that up to maybe a volt with so-called distortion humbuckers.

It would make sense to put a variable gain/attenuator before this thing to get level more adaptable to driving a voltage controlled something or other. The front half of the Adjusticator should work.

I think an eight pin PIC would do nicely to replace the CMOS chips in front of the three peak/holds.