Having an interest in music and liking synthesizer music I thought it would be fun to create an analog version. My primary experience has been with digital designs and robotic controllers, but very little analog work. While there are many software solutions available, I wanted the satisfaction of turning knobs and building the synth from the ground up. So I created a series of PCBs that provide the basic components needed for music generation. I have a sequencer board (working now and fully debugged), an oscillator board (also working), and finally the needed Voltage Controlled Amplifier module board (VCA - fabbed and next on the debug and setup).
Basic Operational Theory :
The sequencer board uses simple inverter based osc for the low frequency that drives a counter whose outputs can be patched into the 3 select control lines of an analog 8:1 mux. The mux inputs are set to various voltages via potentiometers. This provides somewhat arbitrary wave shapes for use with the fundamental frequencies generated by the oscillator board on the VCA board. I am skipping over numerous buffer amps and mixers but they are included and provide more range of tone and frequency options.
Advanced future options:
I would like to add a midi input to properly excite the various segments (even though it is Digitally based) so that I can use a keyboard for input. Currently, I used the potentiometers and a simple push button to drive the boards.