NLC - Envelope follower - build notes

These are my build notes for the NLC - nonlinearcircuit Envelope follower. It's a eurorack module but it's design was based on the Envelope Detector of the Buchla 208 (Music Easel).

The 208 has a a hi/lo switch. Andrew has substituted a gain pot.
The NLC version also has a additional comparator stage to give a gate output.
The NLC build notes are here:
http://www.sdiy.org/pinky/data/ENV%20follower.pdf

The module uses just two op-amps (TL 072)

I mixed the 101 (100pF) and 2M2. - it does not matter as they are in parallel anyway.

The BOM requires:
a S1JL rectifier
Mouser No: 821-S1JL.
There is a long waiting list for this.
A replacement is  Mouser Part No: 583-FM4005-T.
The rectifier is polarized. The cathode end is marked with a band. 
This replacement is slightly too big for the PCB. so i had to solder it on its side.

NLC words of wisdom

I think what I do is positive. in its own way. GG Allin

Jacks, pots, LED

tHE Envelope Follower is ideal for instruments at line level such as guitars, mics and Buchla audio signals.
Synth levels (eg Eurorack) can be a bit hot.
Turning the gain to zero and a input from a VCO seems to trigger the envelope and gate quite well
and doesn't seem to harm the module.
However, I think an additional attenuator in the signal path will give more control over the envelopes produced.

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