Fast analog sw. as VC resistor

John Speth johns at
Tue Jan 7 01:06:47 CET 1997

Mark - 

Thanks for doing the bench work for your experiment.  I'm closely following
this thread and I wonder if maybe in your first trial you are debugging too
much circuit.  By this I mean don't use any comparator in the test circuit,
but rather use your function generator to produce a calibrated and
predictable duty cycle.  I wonder if maybe you are using your comparator
control voltage as a true indication of duty cycle instead of actually
measuring the duty cycle directly.  What I'm suggesting is that maybe the
CV to PW convert is the culprit and not the switched resistor.  I would
think it would be pretty hard to accurately measure duty cycle with
anything but a really good measurement o-scope (but maybe you are?)

Anyway I think the theory is right on, you just gotta tame the beast.

John Speth (johns at
Object Engeering, Inc.
Vancouver, WA

More information about the Synth-diy mailing list