This is, of course, based on Eric Barbour’s designs, with a few twists.
I built a separate sine/square wave oscillator and have put an input jack on the front of the ring mod for input of any carrier signal.
Basically, the first jack is the straight signal input. It feeds a 6ej7 pentode, then the volume pot below the jack, then pin 6 of the sheet beam tube.
The second jack is the carrier input, which feeds 1/2 of a 12ax7, a volume pot, the second 1/2 12ax7, then the beam deflection pins.
The top switch takes the straight input and switches it to the carrier circuit, cutting off the carrier input. This creates some weird and useful sounds, especially in conjunction with the bottom switch, toggles the value of the 12ax7′s first cathode resistor bypass cap between 10 uf and .01uf.
The third pot is screen voltage control for the sheet beam tube and the last jack and pot are output.