Schematics / VCF By Phobos
VCF by Phobos ,shared on the following thread http://electro-music.com/forum/post-358436.html along with other Phobos DIY Schematics ,he wrote on this VCF :
Some of you may recognize a korg MS20 filter in this one which is one of the designs I experimented with and a couple of circuits based on that or similar too. As you can see there is another variable zener circuit in there which has the same purpose as the zeners in the DUAL VCA. I did want resonance controll but no tweeting self oscillation, so adjusted the values for that. But with resonance set at max and a high amplitude input signal it still does oscillate sometimes, it also acts a bit weird with resonance maxed and the filter turned down, but I decided to call that a bonus feature.