Archive of the former Yahoo!Groups mailing list: MOTM
Subject: VCO Triangle/Sine glitches
From: "Paul Schreiber" <synth1@...
After 4-5 hours of basic research, I have ∗minimized∗ the glitch on the top
of the triangle wave (which of course shows up on the sine as well).
This glitch is an artifact of the full-wave rectifier action due to:
a) finite switching times of the diodes
b) diode capacitance
c) finite switching time of the comparator that discharges the main
DC offsets in the sawtooth are trimmed out by using a 'scope.
Now, the glitch itself is 1-2uS wide. That's right, ∗microseconds∗. You can
see it on a 'scope.
You can't hear it, or hear another problem when the VCO is used as a LFO.
The width of
the glitch is constant up to about 12Khz.
Also, if you pass the triangle through a LPF, it goes away.
So, I just thought I'd toss this out beforehand.
If it makes you feel better, the glitch is about 1/2 the one on a Moog
modular. And, our triangle
symmetry is 10X better above 4Khz than Moog's.
"Basic research is what I'm doing when I don't know what I'm doing." W.Von