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

Dave M dgminala at mediacombb.net
Fri Jul 22 03:38:03 UTC 2011


> Hello,
>
> I have a PRS10 rubidium which gives a 1pps output.  The output is a
> 10 us positive pulse.
>
> I need to convert that to a 50:50 duty cycle pulse.  Still 1pps.
>
> I'm hoping for a simple circuit rather than having to use a pic.
>
> I don't mind a bit of propagation delay, but I need to preserve the
> low jitter on the rising edge, and hopefully also the falling edge.
>
> Any ideas out there
>
> Regards
>
> Steve


The simplest way that I can think of is to feed both inputs of an XOR gate 
with your 1pps signal to double it to 2pps, then feed the XOR output into a 
flipflop to get back to 1pps with 50% duty cycle.  You might have to delay 
the 1pps into one of the XOR inputs with a small RC to reliably trigger the 
flipflop.  Use 74HC or AC gates and the jitter should be tolerable.

Cheers,
David
dgminala at mediacombb dot net






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