This is an analog filter based on the 1974 SEM filter. The original early design did not self oscillate into a sine wave. This one also does not self oscillate. The sound, however, makes up for that. You get the original notch sweep, and incredible band pass mode at such a low friendly price.
Added Features
-onboard VCA
-onboard envelope generator (decay)
-variable trigger input circuit. Emulates a Vactrol.