[Elecraft] On zero beating

[Francis Belliveau]

On: Friday, January 18, 2002 11:03 AM
"Dan Barker" <dbarker@visioncomm.net>
wrote:
...
Years ago I built a box with 5 LED's and PLL (741's - DTML decoders, if
memory serves)detectors driving them tuned for for 700, 750, 800, 850 and
900 Hz drive.
...
Five PLL chips to drive five LED's seems like a lot of circuitry to me.  I'm
no EE but I thought that the PLL chips put out a voltage that was supposed
to be proportional to how far out-of-tune the input frequency was.  This
voltage would normally be used to control a VCO such that the PLL kept the
VCO on frequency.  Couldn't one use a PLL to drive a bargraph display making
the entire circuit take about 3 chips total?

Am I way off base?

Fran, KA4FRH
K2 s/n 314