It was emotional experence to hold this one. After all, this is THE VCF which started it all, and is now recognized by sound all over the world and cloned in nearly thousands of incarnations. The moog ladder low pass filter. In this photo you can see the capacitor banks that were switched with rotary switch (the crapy type) and the transistor ladder itself. Yellow dots show that transistors were hand matched and selected to color-coded bins. The rest of circuitry was on 2nd PCB.