On Sat, 15 Jun 2002, Edson Brusque (listas) wrote:

>Hello,
>
>    I'm looking for informations about using PLLs (Phase Locked Loops) at
>low to mid frequencies (from 20Hz to 50kHz).
>
>    I've googled the web, searched National's ANs and just can't find how to
>use a 4046 to detect a frequency like Peter L. Peres sugested in a reply to
>Dale Botkin about guitar tuners.

What is the problem ? Get a datasheet and use this connection:

(stop - I can't find my ancient CMOS applications book now). Here are
connections from a schematic I developed before:

3,4 5,8 gnd 150pF between 7 and 8 input on 14 (capacitive coupled) PLL
components between 13,9 and GND as in the data sheet (in my case R between
13 and 9 and C from 9 to GND) VCO tune and pad resistors to gnd from 11
and 12 resp. demod out from 10 from a r to gnd (~10k) if needed.

You want the VCO signal to go to the PIC, that is pins 3 and 4 in this
case. It is CMOS level oscillator output (suitable as input to a PIC).

The 4047 is user friendly and if you have a scope you will get it to work
very fast. My notes say you need 250mV (pk) in to work at 150kHz and 5V.

Definitely read a PLL cookbook. I am sure someone will recommend one on
the web.

Peter

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