Minidrone is a five voice drone module. A single module contains five reverse avalanche sawtooth oscillators, with individual pitch control and an on/off switch. The five voice are summed together and sent through a VCA with an attack/release envelope generator. The EG is triggered either with the push button or the toggle switch on the front panel (so you don’t have to hold down the button). Each module also has a master tune knob that varies the pitch of all five voices at once.
Project files live here: GitHub - mprosk/minidrone: 5 voice drone module with built in AR amp envelope
I built up five modules (since that’s the JLCLCB minimum order quantity 
) and put them all together in a box. This is sort of one-half of an Elta Music Solar 50. The outputs of all the modules are summed together and sent out that little aux panel. I also included an LM4808 based headphone amp.
Stuff for that board is here: GitHub - mprosk/headphone_amp: Compact headphone output module based on the LM4808
Power is supplied from an external 12V AC source that I rectify, smooth, and linearly regulate, also on a custom PCB. I know you can buy boards that are basically this but I wanted the experience of designing my own.
Project files here: GitHub - mprosk/supply_lvac: Low Voltage AC to Eurorack-style split-rail DC supply
They’re not in KOSMO format, they’re more Eurorack sized, but they’re not really modular modules anyways since there’s no patch points at all. I always intended for these to be built up into more of a self contained instrument not really put into a modular system, so ¯\(ツ)/¯ It would be pretty trivial to make this into an actual patchable module down the road.
This was my first real analog synth project that actually made it out of the schematic and into my hand, so that was incredibly rewarding. Very cool seeing something you sketched out on the breadboard…
make its way into the real world…
Quick and dirty demo vid is here, pardon the bad audio and horizontal framing. I’m planning on doing a real demo vid soon, I’ll update the post with it once its done.
