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

[Bruce Griffiths]

Dave M wrote:
>
>> 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
>
>
>
>
All that will achieve is generating a pulse about 10us wide of 
indeterminate polarity.

Bruce