Flickr user Equaliser (Steve Woodward) has a nice pic of his DIY Polivoks style filter posted. The kit is available through Papareil Synth Labs and on their site you’ll find some good historical information and documentation of its workings. Here’s a shot of the schematic (click for link to original .pdf).
Steve has some great audio clips of the filter in full effect here
I can’t imagine anyone will need this but while I had my Electrix Filter Factory apart for cleaning and routine maintenance (i.e. screwing around w/ it) I decided to clean up the faceplate and scan it in. For Cubase users, this would make the perfect graphic for your user defined MIDI Device Controller… (If it’s for an Electrix Filter Factory that is). I’m thinking a redesign and custom faceplate plate might be in order.