Sometimes the simplest things are the most fun. The Squigglebox is one of the silliest and simplest things I’ve ever built – yet it never fails to make people smile. It’s a touch-sensitive synthesizer, with the pitch controlled by touching two metal springs that I found on the street. They bounce around hilariously, and the sound comes out of a big speaker in the middle. You can make some surprisingly expressive sounds, despite the total lack of controls.
It works particularly well in schools, as a way of getting kids to think about electronic music.
It uses a very simple 40106 chip oscillator circuit and a 386 chip amplifier. There’s an input and an output, so you can set up an effects loop as you see in the video (or plug it into a sound system or use the amp on its own).