This synthesizer I built uses an array of what appears to be generic clones of of one of E-Switch's SS series subminiature snap-action (micro) switches for keys. They are configured to cascade from right to left, as to imitate fretting of a string, all the way to the root/fundamental, which is equivalent to an open string, activated or muted by the FUN switch. All the notes on the keyboard are tuned using trimmers.

The synth has 4 negistor/avalanche oscillators made from 2n3904 NPN transistors hooked up in a really naughty way. 2 oscillators are the drones, and 1 for the lead, with one performing vibrato (controlled by VIB switch) on the lead by tugging on its current reduced power rail. The module at the top left converts 5v from USB to the 15v needed for the circuit.

2 of the knobs and switches shown are not in use, they were originally for a suboctave circuit I never got working, they were left on for aesthetics until needed or salvaged. The rest control the drone pitches, balance, tone, and volume. KLS was originally a kill switch, which changed to high pass filter.

The sound is like that of bagpipes or a hurdy gurdy, but with a slightly more electronical quality, with a saw-like waveform typical of avalanche oscillators. The demo shows the synth without the wooden supports, but is essentially the same otherwise.

Demo Video Link, Odysee Mirror

 

Here is a schematic (View Full size)