The F0 is a minimalist, analog, square wave synthesizer with custom 3D-printed piano keys.
Here’s a quick demo of the DIY synth in action:
The heart of the F0 is a Voltage Controlled Oscillator (VCO) from a CD4046 chip. A 9v battery feeds a 5v regulator to create a constant reference voltage, which is then dispersed across buttons, diodes, and trim potentiometers (13 of each) to make voltage dividers.
Potentiometers tune each note, the diodes prevent the notes’ voltages from contaminating each other, and the button switches ensure that the voltage only passes when the user intends for the note to be played.
See the project site for build details.