[sdiy] Upper frequency limit for VCO

[René Schmitz]

Hi Brian and all,

Brain Dekork wrote:
> Does anyone know what the upper frequency limit for the
> integrator-with-reset VCO is?  I want to divide it down to mix
> footages.

There are lots of variables involved. Cap size, reset time/discharge
circuitry and the speed of opamps/comparators... I just measured a VCO3
to hit 200kHz. But the waveshape is a triangle then (with some "ring"),
and the franco compensation does reduce the amplitude to about 1/2. Also
the stability up there isn't really great... The low end of that is
still way _below_ audio, about 15 minutes per cycle.

I have used integrator with reset type VCOs (albeit only in uncritical
situations, where tuning curve and stability are not important) up to
500kHz. An example of this is the clocking VCO for that three phase LFO
currently discussed in another thread.

Cheers,
  René


-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159




-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159