AW: PLL pitch tracker

Haible_Juergen#Tel2743 HJ2743 at
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 ?



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