This is the simplest possible synthesizer: No modulation, no envelopes, no filtering, no built-in effects - just a single relaxation oscillator controlled by a single variable resistor.
It uses a pencil as a conductive stylus for adjustable contact on a resistive strip made by applying a thin layer of graphite (i.e. scribbling with a pencil) on paper.
Normally, the frequency varies smoothly over the length of the paper strip, but Auto-Tune allows you to restrict the sound to a discrete set of pitches, just like a real Stylophone!
Schematic: https://drive.google.com/open?id=1bh2IWXtWhqcnlal7LtJFpqBpQJm7U_E7
Component list: https://drive.google.com/file/d/17c2H5zRdbnVsVDKD4IKAIJimk3u6k352/view?usp=sharing
I think the circuit I used might be one of the simplest possible ways to get this to work. It does not use a 555 timer, or any other IC chips.
Original Circuit: https://digilander.libero.it/bubblegate/ecircuit.html
Music in this video:
Sirius Jazz by Jeremy Blake
https://www.youtube.com/channel/UChnxLLvzviaR5NeKOevB8iQ
Contact High by RKVC
https://www.youtube.com/channel/UCowgKeMGXKY038qwuf3yYlw
#psychotenuse