[time-nuts] 50:50 duty from a PRS10

Magnus Danielson magnus at rubidium.dyndns.org
Thu Jul 21 18:32:31 UTC 2011


On 07/21/2011 07:48 PM, Chris Albertson wrote:
> How close to 50% duty cycle do you need.  is 0.50 good enough or do
> you need 0.500000000 ?  If all you need is 15% accuracy a 555 timer
> set up to make a 0.5 second pulse would work but if you need better,
> then maybe a phase lock loop with a much higher than 1Hz oscillator
> and then you divide that down to 2Hz and the 2Hz triggers a flip flop.

Take the 10 MHz and divide down to PPS rate, synchronise with the PPS if 
it is important. Otherwise you can go mid-ways to only divide down a 
little, then use that to synchronise the output of the 555 and then 
synchronise it in a second DFF with the 10 MHz. There are many ways to 
hold state, a capacitor is one such way.

Cheers,
Magnus




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