Four adjustable square wave oscillators (of varying pitches), one filter and a current-starvation pot - everything you need in one place to create either a godawful racket or a nice, clashy, percussion-style sound source.
No voltage-controlled frippery, just lots of knobs to twiddle.
The installed CD4070 logic IC can be replaced with any suitable 12V tolerant CMOS IC to create different timbres (don't be tempted to use 74HC-series chips as they're only rated up to 5.5V, and applying 12V will lead to quick release of magic smoke)
