[time-nuts] Low cost synchronization, kitchen appliances
Tom Van Baak
tvb at leapsecond.com
Sun Aug 21 10:03:56 EDT 2005
> > For some countries will 60 Hz or 50 Hz no longer be maintained on 24 h
basis, so it may be
> > a bad idea to depend on it.
> I keep hearing, on this group, that the powerline is no longer sync'd to
utc, and evidence for
> that fact being a lack of motorized wall clocks. Well, clocks that sync
to the powerline are in
> universal abundance in the US. Virtually every clock on kitchen
appliances is sync'd this way.
> The clocks on VCR's may be reset from time to time by a tv station, but
the timing signal is
> still the powerline. Basically, any appliance, or device that plugs into
the powerline is likely to
> use the powerline for its timing function.
Correct, my measurements clearly show that
mains power is steered to UTC. See:
If there's anyone from the power industry on the
list I'd be interested to hear first-person technical
details of how phase is synchronized, both short-
But I'm not sure I agree with your claim about
kitchen appliances. It seems to me almost every
kitchen, electronic, wall-clock, and entertainment
appliance being sold these days uses quartz-based
clocks, regardless if they are mains, wall-wart, or
battery powered. I'm not sure how to confirm the
accuracy of this hunch, though.
I suspect there are several factors in the trend
away from mains-clocks to quartz-clocks:
1) Digital or analog quartz movements are dirt
cheap (so it's a cost saving measure).
2) If the product is intended for sale in Japan
(where both 50 Hz and 60 Hz mains co-exist).
3) If the product is intended for sale world-wide
(there is a healthy mix of 50 vs. 60 Hz and 120
vs. 240 V across the planet).
4) The explosion in the use of switching power
supplies in home electronics (which are immune
to local voltage / frequency conventions).
5) The explosion in the use of microprocessor
based control of appliances (where the CPU(s)
are driven by an n MHz XO and date/time/display
functions are managed in firmware).
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