Tom Van Baak wrote:
Phase lock the crystal to the 50/60 Hz powerline? The signal seems
to be ubiquitous.
Not sure if this would work to the level you need.
See:
http://www.leapsecond.com/pages/mains/
/tvb
Tom,
I'm not sure if it is true, but I understand in the UK there are
50*24*3600=4,320,000 cycles of the mains between midnight and midnight.
So whilst a clock set right at 2pm in the afternoon might not be right
at 2pm tommorow, one set correct at midnight will always be right at
midnight.
That was my understanding, but it might be an urban myth, with no basis
at all.
Given that there are very few electric clocks around now in the UK, I
doubt keeping exactly 4,320,000 cycles between midnight and midnight is
that important to the electricity companies now.
I wish they could keep the voltage a bit more stable though - I have
measured as low as 183V here, when its supposed to be 230V. Some houses
near a friend of mine managed to get 415V instead of 240V (as it was
then), when some idiot repaired a cable but managed to hook up two
phases rather than a phase and neutral. Quite a few TV's and videos did
not like 415V too much!
--
David Kirkby,
G8WRB
Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/
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