This is a 4-pole high pass VCF circuit with controllable resonance. It uses diodes as the controlling element.

Demos, build documentation, drill guide, are available here.

Unfinished panels are drilled by hand in my garage, they are bare aluminum that may be scratched.  They are intended to be painted, etched or otherwise finished later.

Pre-Assembled Modules are built after the order comes in.  Build time can be a few days or a few weeks depending on what parts I have on hand.  When ordering, please leave a comment at checkout if you have preferences on what color(s) the panel is painted.