This was originally a child's toy called the “Stylophone Beatbox”. I had heard rumors this was a prime candidate for circuit bending, so I bought one and went to work.
Circuit bending is a synthesizer hobby where people take toys and modify them electrically to make strange unearthly sounds.
I reverse-engineered the schematic, added pitch control, bass rumble, treble distortion, a weird clock-feedback loop, reset switch, and over-extended the control ranges allowing you to put it into a glitch mode.
I was initially worried about frying the circuits, so I laid out the whole schematic as to avoid shorting anything I wanted to keep. In my research I learned most sound making devices actually have a resistor that sets the pitch, even if the sound is sampled from a digital file. Got to do some lathe work when making a new stylus, which was fun. Ground my own HSS tool bits for this as a learning exercise.
A lot of the controls on the original toy were quite awkward to use, so I totally removed them and wired up nice big knobs and buttons to make using it a lot easier. This makes it much quicker to play live as well.
One thing I'd like to add in the future would be full midi control. This would be quite straight forward as almost all the inputs are referencing ground or 5v. A very small micro controller, channel dip switch, and a few transistors would be mostly all that's needed.
©2022 Kevin Whitfield