Korg MS 20 f->Volt Converter

[Martin Czech]

> There are some good f/v converters. I traced out a old 360 Systems
> "Slavedriver" an early guitar to synth adapter. After the filtering to
> remove harmonics, the comparator to extract the zero-cross (square wave)
> information (same same) the Square wave (fundamental) was used with a ramp

SNIP

Yes, I think this is a better approach, given that the input is a perfect
square.  It should be possible to set up a dual ramp system which does
measurements in both parts of the wave.  To get a better square wave there
are clever peak detectors (cascaded), I have patents from Moog and Bode
about that somewhere.  The idea is that the largest positive peak and
the abs largest negative peak give better information about the period
then zero crossings do.  Just think of a fundamental with one harmonic,
the fundamental only beeing 10% of harmonic amplitude. *YOU* would figure
out the frequency by looking at the peaks, not at the crossings, right?

> with his "Etherwave" theremin, I don't know if it is on the web (I bought
> one).  If your interested I'll try to find the 360 Systems circuit. I had to
> trace it out by hand (with all chip numbers dusted off). Maybe some errors
> but I was able to identify all thr chips from their pinouts (4000 CMOS).
> Harry Bissell

Yes , the 360 circuit would be interesting.
Only if not too much work to dig it out.

Thanx

m.c.