Arduino-VDCO VS HAGIWO-Arduino-VDCO

for Arduino look into any of the hagiwo stuff. The additive VCO sounds incredible. Or take it a step further and try the luislutz branch: https://github.com/luislutz/Arduino-VDCO. Also anything from Eddy Bergman's site - I've built at least 8 of his projects and they've all worked from the get-go.

second this recommendation. The luislutz branch looks promising as well https://github.com/luislutz/Arduino-VDCO

The luislutz remix of this is nice too, since it combines the additive, chord and FM voices as a switchable modes in a single module. I forked it with some tweaks and a cramped stripboard layout.

I've seen this arrangement in some other projects (eg this) but I'm a bit worried that whatever modulation source I plug into the CV jack will get a brief 5v just before the TN disconnects. Should I be worried?

I'm having a lot of trouble with the output stage. I've copied various designs based on a TL072 or MCP6232 but it's very very quiet still. Tonight I'll try rebuilding the output stage based on this design. Wish me luck!

DIY: - The case! Just a plywood box. I got the wood cut to size at my local home center store and glued it together at home. I use wooden batons instead of metal rails, and just screw the modules to the wood. PSU is a budget unit from SF Innovations. - Hagiwo VCO/LFO (made the mistake of building his first version, should have done the revised version) Very handy - a nice pure sine, tri or square LFO - can go to high audio range, but only goes from 0 to 5v. - Hagiwo Additive VCO - sounds beautiful! Love it. But if I were to do it again, I'd build this variation instead, which runs not just the Additive VCO code but also the Chord VCO and FM VCO, all in one unit. There are two difficulties with Hagiwo builds - the instructions are in Japanese (use Google Translate) and he generally only gives circuit diagrams so it's up to you to transfer that to whatever perf board you plan to use. That's the hardest part for me. - Eddy Bergman Mixer Attenuator, Simple Dual LFO and Noise Module. Mr Bergman has loads of modules to build, and provides circuit diagrams and veroboard layouts that are easy to follow. Some of the boards are a bit big for Eurorack so allow plenty of depthin your case (>12cm at least). The Noise Module is great, especially the 'grainy noise' which can sound like anything from intermittent vinyl record pops through Geiger counter to heavy radio static. - CuSi attenuverter - very useful indeed for taming modulation, etc - Some passive mults, and FX send/receive

- Hagiwo Additive VCO - sounds beautiful! Love it. But if I were you, I'd build this variation instead, which runs not just the Additive VCO code but also the Chord VCO and FM VCO, all in one unit. There are two difficulties with Hagiwo builds - the instructions are in Japanese (use Google Translate) and he generally only gives circuit diagrams so it's up to you to transfer that to whatever perf board you plan to use. That's the hardest part for me.

The luislutz remix of this is nice too, since it combines the additive, chord and FM voices as a switchable modes in a single module. I forked it with some tweaks and a cramped stripboard layout.