Here is the output from pin 7 of the IG00153, with the scope set to 0.5mS/div and 0.5V/div:
Notice there is in fact a definite one-shot pulse that leads the ramp. This pulse is about 0.45V amplitude and 30 microseconds in width.
Another look at the waveform, at 1mS/div:
Here is the one-shot pulse viewed at 10uS/div, where it can be seen that the pulse is abvout 30uS wide. This matches up with the external RC time constant that is t=(R)(C) = (24.5K)(1200pF) = (24500)(1.2E-08) = 2.97E-05 or about 30uS:
Lastly, the sawtooth after being inverted in the IG00158 WSC chip:
So, it is apparent the one-shot pulse is a factor in the final waveform/sound of the CS VCO.
Update: CS VCO built as module from standard parts completed.
Here are a couple of images of the 1U module:
The 1U module has frequency, vibrato (FM) level and initial pulse width controls, plus a to-be-added fine tune control. CV inputs are 1V/Oct pitch, FM CV IN and PW CV IN. Outputs are sawtooth, pulse and sine.
While this version is scaled for 1V/Oct operation, it is a simple matter to make it do V/Hz (linear) response with a different front-end current control circuit. Well, I say simple but the method to still obtain exponential vibrato with V/Hz pitch tracking is a little tricky. Thanks as usual to JH for the solution to that one.
Scope images of my VCO:
The sawtooth at 6Vp-p:
The 30 microsecond reset pulse:
The not-quite calibrated sine:
VCO octave test
Mid-range test of sawtooth
VCO raw sawtooth timbre
comparison -- guess which is the CS VCO ;)
More later.