Here’s a pair of them freshly built:
Basically, the way it works, is that this is a sawtooth core VCO. The main sawtooth output then goes through a singular version of the saw-animator circuit that I mentioned above (Hutchins / Ludwig). This basically shifts the phase of the sawtooth.
There are then two of each subsequent wave shaper. One off the non-shifted saw, and one off the shifted saw.
So Saw>Triangle>Sine for phased and non-phased.
The tricky part is removing the rectification glitches in the shaped waveforms off of the phased sawtooth. That took me the longest time to figure out, and is one of the main improvements of my VCO over other ones that I’ve seen before. Also, getting the phase modulation to smoothly go through zero via CV was a bit tricky. These are the reason the boards are so large, and use so many parts. There’s a lot of brute forcing going on to get everything just right. There is one final stage, which sums the phased and non-phased sine waves together. This can be done externally for the other wave shapes as well, but the goal of this VCO was to make DX style tones, so I spared the parts for the other waves.
Anyway, that’s more or less it.
I typically use Burr Brown op amps, but these were built to test different (and less expensive) types for another project, to see if the cost could be brought down a little bit without sacrificing the quality of the output. We shall see.