Hi there,
Finally got to built 3 units of my VCO design. I had the front panel and PCBs made at JLCPCB.
All project and Gerber files are available here: GitHub - DeMarco/DMH-VCO-40106: VCO module based on the CD40106 Hex Inverter chip
I like the philosophy of using general purpose, readily available components only, so I’m drawing heavily from the circuits teached by Moritz Klein in his YT channel. This VCO is built around a CD40106 chip and a pair of BC558/548 as linear-to-exponential CV converter. I’ve put together a lot more extra features, like a Sync input and trimpots to adjust the range and centering of the Fine Tune knob (inspired by LMNC). But of course the most prominent addition is the tuner, another LMNC idea I stole. I never got around to learning Arduino, but I have experience with programming PIC and AVR microcontrollers in pure C with the help from the datasheet, and I wanted to challenge myself to come up with a simple tuner design of my own. Main difference is that I wanted to use 5 LEDs to display the note accuracy, and a separate LED to signal sharp (#) notes. I also have a switch to turn the tuner off in case I don’t want to be bothered by the flickering lights. Unfortunately I learned the internal RC oscillator of the microcontroller I used (ATtiny4313) is of course not extremely precise, so there will always be a tiny offset if I compare the central frequency with the one measured by a tuner in Ableton, for example. I have ideas to make it better, but I’ll focus on something else for now.
Here’s a demo. The LFO signal on VCO #2 comes from a Behringer Neutron offscreen.
