This module is based on a design from Electronotes for a "High-ripple VCF". It's basically an "animated filter". Without any modulation source, it will modulate the cutoff frequency based on the "animation level". It does this via its 3 internal very low frequency oscillators at 1.6Hz, 1.35Hz and 1Hz summed. It also has inputs for modulating the cutoff frequency via CV and envelope. Inside, it's actually made up of 3 low-pass filters in series, each having a different fixed Q (resonance), the 1st filter having the lowest Q and the last having the highest.

The PCB is rather large and may not fit in all Eurorack cases, it's 3.1"x3.7".

This is a new version of the board with the 6 CA3080s replaced with LM13700s.

Schematics, BOM, and docs are at:

https://github.com/mikemoretti3/Synths/tree/master/electronotes/misc

If you have any questions at all please let me know.

Sound samples:

No modulation, just twisting knobs

Modulated via external LFO