**Update**
The full build guide is now available here:
**End of update**
I made a few small changes to the V3 code;
https://github.com/gary909/Helios-Arduino-Synth-V3.1
https://github.com/gary909/Helios-Arduino-Synth-V3.1
V3.1 - Minor Updates
*Improved Filter Resonance (?). Apparently After setting resonance, you need to call setCuttoffFreq() to hear the change. Swapped in code.
*Increased note sustain from 10 seconds to 60 seconds
*OSC OUTPUT made louder on audio update>>9; // changed down from 10 to 9 because was louder
Still working on the LFO section, hopefully not too much longer...