VCLFO

An 8HP wide LFO/VCO module with voltage control over frequency.

Three frequency ranges, can go from minute long periods up to full audio range
CV frequency control with attenuverter, adjusts CV sensitivity and polarity
large CV range of frequency control. With the right settings this can also be used as a sort of freeze/run gate.
exponential CV response, does not really track 1V/oct in any setting though.
separate triangle/ramp and square wave outputs, each with level adjustment
switch for ramp or triangle output (also transforms the square output into a pulse output)

The circuit is based on a vactrol (LED + photoresistor) to control the frequency of the oscillator. Because of this the frequency control is not very precise, it will have a response time of a few milliseconds to quick changes in control voltage and the frequency might also drift slightly for some time after a change.

This module was originally built to provide an additional modulation source for my Arturia Microbrute. It turned out to be more useful than expected so a few more have been built :)

Schematic, PCB and panel licensed CC BY-SA