AW: PLL pitch tracker
HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de
Fri Feb 16 21:10:00 CET 1996
>So the next logical step was to try a phase-locked loop, and use the
> VCO loop control voltage as the recovered frequency voltage output. I
> realized that if an exponential VCO is used in the PLL, then the
> voltage output would be 1 octave per volt, since the loop filter will
> put out whatever it has to so that the VCO is phase-locked to the
> external signal input. So I built a simple exponential VCO based
> around the guts of the EN tri-square VCO (input summer, matched PNP
> pair, 3080 integrator, 3140 buffer, 3080 comparator). Then I built a
> wide-band phase comparator with a 74LS00, followed by a loop filter.
> The output of the loop filter controls the VCO frequency.
> The capture range of this PLL is from about 10 hertz to about 5
> kilohertz, which should be perfect for musical use. The loop filter is
> highly damped and extremely fast-responding, with hardly any jitter.
> An additional op-amp is used for a little extra filtering and to
> buffer the voltage output for driving external pitch sources.
Now this is a circuit I would love to see in details! Would You mind to
post a uuencoded GIF or a FAX of that in my direction, Gene ?
More information about the Synth-diy