will have to go DCO

It is going to be very difficult to get a decent and stable frequency out of the prototype. I even tried removing the MCP42100 (which is obviously not created for this purpose, will use it later again in the filter), which only resulted in a little more stability. Still drifting around 3 hz when tuning at 440hz. Not acceptable for me, so I’ll go the DCO road. Inspired by the Roland Juno 106:

source: Electric druid