This is a licensed adaptation of the original Serge VCF
The CGS77 is a 2-pole state-variable filter with 12dB/octave slopes on the [LOWPASS] and [HIGHPASS] outputs and a 6dB/octave slope on the [BANDPASS] output. The CGS77 does not self oscillate.
By turning up the [Q] resonance control, the filter can used as a percussion sound generator - xylophone, wood block, drum, bell, gong, vibraphone.
It does not have a 1V/Octave input but does have a scalable [VC F] input, so can be adjusted to track to play tunes, etc.
NB: This new revision does not include any unassigned buffers or LED driver.