Simple analog DIY synthesizer using just a few components

Simple DIY synthesizer using transistor in reverse avalanche mode.
I've built three oscillators and connected those to a small amp to show how it sounds.

This synth uses very few components.
1k resistor
10k potentiometer
100k resistor
1 LED any color
2n2222 on 2n3904 (or other similar npn transistor)
0.01 to 10mF capacitor.
So we can call this a cheap, 1$, one transistor synthesizer.
6 component synthesizer, 5 minute synth.

https://drive.google.com/drive/u/0/folders/1DGM-V_QwiU5idF-qyw74YMUBrNTVBXmM

Transistors like 2n2222 and 2n3904 have a reverse breakdown voltage of roughly 12-15 volts. Battery charges the capacitor through the 1k resistor, when capacitor charges to the point of transistor's greakdown voltage, transistor becomes conductive an it lets the current through and discharges the capacitor through the LED. If you take a capacitor of 0.01 to 5mf and connect one of its legs to the transistor, and another leg to the amplifier or an oscilloscope, you'll be able to hear/see the signal.

An article that describes the theory behind this:
http://www.kerrywong.com/2014/03/19/bjt-in-reverse-avalanche-mode/