ChairganSynth
a simple synth made almost entirely from recycled materials
The ChairganSynth was constructed as a temporary device to make use of the Chairgan's keyboard before it was attached to the Chairgan. It utilized two PIC24 microcontrollers, one of which was stolen borrowed from the tinebot, to generate 25 square waves simultaneously.
The key springs, made from an old bandsaw blade, also serve as switches that connect each square wave to the output via the foil key contacts when a key is pressed. When a key is released, the spring connects the signal to ground via another foil contact to midigate bleeding of the notes.
Here it is with the lid open. You can see the foil key contacts and some of the wires.
Here's the inside close up. In addition to the key contacts, you can see the ends of the band-saw-blade springs and more of the wiring. I've lifted up the circuit board so you can see its underside.
Lastly, a closeup of the circuit board. The 2 big ICs are the PIC24s, and the little Adafruit modlule on the left is a 3.3v regulator so they can be powered by USB.
Here's a short video I made at the time: