YUSynth Mini-Moog VCF Module

I assembled a YUSynth Mini-Moog VCF module for a customer.  They sent me the assembled panel and PCB and I made the bracket, wired the module, verified operation, made some level modifications, and calibrated it.  The PCB appeared to be home etched but had black silk screen on the front side.




The PCB already had square pin connectors on it so I used Pololu crimp connectors as the terminals, housings, and crimp tool are very affordable.  I changed the power connector to a MTA style so it would be polarized.  It was 6 pin but I used a 5 pin to not confuse it with a Dotcom connector since the pinout is different.


I made a short adapter cable to a Dotcom connector.  Since they don't make a male cable end connector, I encapsulated the wire connections in epoxy to insulate and hold the pins in place.




The output level in self-oscillation was a maximum of 3V pk-pk so I increased R32 to 430K for a 10V pk-pk output.  I adjusted the range of the filter for the lowest possible self-oscillation frequency that would self-start which was ~130 Hz.  Note the amplitude at this frequency has decreased to 4.6V pk-pk.


The maximum self-oscillation frequency was 23 KHz and the output is 10V pk-pk.


I changed R5 to 22K to provide a 10V output with a 10V input signal with the input level set to 75%.  This image shows a saw waveform with a bit of resonance.


This image shows a square wave with a lot of resonance.  The input level control can be over-driven just enough to make the filter interesting.