[time-nuts] World's most accurate PC clock!

Rick Karlquist richard at karlquist.com
Sun Jul 3 13:25:18 EDT 2005

Slightly OT:  Does anyone know if there is an "atomic clock"
(the WWVB driven type) that interfaces to a PC via USB or
something, such that the PC time is regularly updated?
This would solve my PC time problem.  (I need this to work
w/o internet access).

Rick Karlquist

Poul-Henning Kamp said:
> In message < at>, "W. D."
> writes
> :
>>Is there a 'HowTo' for this somewhere?  How many pins are=20
>>connected and to where?  Where do you mount the chip?  Any
>>batteries involved?
> This is a little bit beyond "HOWTO" stuff.
> You need to find a suitable PLL chip.  ICST is a major manufacturer
> of these.  Most of them have anti-DYI pin-spacing though.
> Then you need to locate the Xtal on your motherboard which drives
> the clocks.  Again, a good place to start is to look for a PLL
> chip from ICST.  Usually there is a 14.318MHz xtal right next
> to that, but some botherboards use different frequencies these
> days and generate the 14.318MHz by PLL instead.
> You can then either remove the existing xtal and feed your signal
> to the right of the two holes (experiment or read datasheet for
> the on-board PLL chip) or you can try override it while it remains
> on the motherboard by feeding your signal into it.  Overriding
> gives jitter and most modern motherboards don't like that.
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by
> incompetence.
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