[sdiy] digital clock schematic

[Peter Swarbrick]

Tuj
what you are looking for is a phase-lock-loop frequency synthesiser. Very
commonly used in RF tuners for channel selection, there used to be a nice
pair of Motorola chips to do this very thing . You could program them with
BCD switches and Voila - programmable frequency !. The latest versions are
serial programmable only so you may need to get into PIC territory to
control  them.(or possibly just use a PIC directly ) Alternatively, you
could use the BBFOC (big board full of chips) method and design your own. I
did something like this many years ago to produce 0.1HZ resolution clocks to
drive Film camera motors, but over a much smaller range.
Best
Pete
----- Original Message -----
From: <tuj at fuse.net>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Friday, December 17, 2004 1:28 PM
Subject: [sdiy] digital clock schematic


> I'm looking for a schematic for a square-wave osc (TTL or similar) that
can be locked to various frequencies.  I want something were I can input the
desired frequency as a binary number and have the osc produce it to within 1
Hz.  Range needs to ideally be 1KHz to about 2MHz.
>
> I was thinking the way to do this would be to use a crystal osc at say
10MHz, then compute 10MHz/desired frequency to get the ratio, and use a
counter to count the oscillations, resetting when it matches the ratio
number.
>
> Am I on the right track?  Better ways to do this?  Thanks.
> -tuj
>
>


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