[time-nuts] Power supply for Thunderbolt

Bruce Griffiths bruce.griffiths at xtra.co.nz
Tue Aug 5 20:46:44 EDT 2008


Bob Q wrote:
> I had a similar problem with my home-brew design.  I found a "blip" with 1 
> second  period on the output of the error amplifier.  I couldn't eliminate 
> it with extra power supply filtering.  The high gain of the error amplifier 
> picked up a very small voltage that developed on "ground".  I solved it by 
> supplying the phase detector and error amplifier with a separate 5 V supply. 
> I tied the ground pin of the new 5 V regulator very close to the phase 
> detector ground pin.
> Bob Q.
>
>   
Bob

That involves an internal modification to the Thunderbolt which isnt 
really necessary as the problem is known to vanish when the power supply 
is quiet enough.
For performance with other power supplies see:
http://www.leapsecond.com/pages/tbolt/noise.htm

The only real question are:
Is possible to filter the given power supply sufficiently well.
Which power supply rails need to be filtered?

Bruce



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