I wanted to prototype all of the circuits for the polysynth, so made a start with the VCO. I also wanted to make sure that the panel layout I’ve designed would actually fit.
I’ve picked up all the chips I need from Alfa – 4 x AS3340, 4 x AS3320, 8 x AS3310 and 4 x AS3360 – along with a whole bunch of cheap pots and stripboard for prototyping.
The circuit is based on Look Mum No Computer’s CEM3340 VCO, with the added PWM and I’ve also added an FM input based on schematics from Electric Druid and the AS3340 datasheet.
I haven’t actually redrawn the schematic yet, just the stripboard layout, but I’ll post it here when I have.
Happily, the panel components all fit ok, and I can fit 2 VCOs on the stripboards I have, which are also exactly the right width by pure chance! I’ll be stacking them 2 deep.
I built up the circuit and wired up all the panel components. I’ve also made a little bus board prototype which I’m hoping will be happy to power all 4 VCOs eventually.
Popped the chips in, attached all the wires and gave it a little test…
Dead happy with that. Everything works as it should and it sounds great.