[time-nuts] How to get 32.768KHz from 10MHz.

Magnus Danielson magnus at rubidium.dyndns.org
Sat Aug 2 12:44:57 EDT 2008

Max Skop wrote:
> How does one get a 32.768KHz signal from our 10MHz reference.
> There does not appear to be a nice divide ratio to do this.
> With a locked 32.768KHz signal one could lock the oscillator of  any of the cheap (low cost) LCD clocks that are available with nice big digits, temperature sensors and calendars, etc.
> Any suggestions on how to do it??

I would consider locking a 8,192 MHz crystal to the 10 MHz. The 
comparator frequency of 16 kHz using a division of 625 from the 10 MHz 
and a 512 from the 8,192 MHz oscillator. The 32,768 kHz output can be 
generated by first dividing by 125 and then a division by 2 for propper 
50% pulse ratio.

Not too complex and the comparator frequency is high enought for a nice 
filter should be able to do it. I would use a SR flip-flop for phase 
detector. For this kind of work they work very well IMHO.


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