On 1/22/12 7:12 AM, [email protected] wrote:
There is always a lot of discussion about various timebases for clocks on
this group. One I have never seen discussed is using a high quality watch
or clock movement. I have some real neat antique pocketwatches. I thought
it would be real neat to set up a pocket watch movement where you can see
all the works (It would have to be in a dust proof enclosure.)in
operation. I thought you could pick off the oscillations of the balance
wheel using a fiber optic through beam photoeye on one of the photoeyes
made for detecting tiny objects. I see these in my industrial maintenance
work from time to time. The watch could be set up with a electic winding
mechanism. With the photoeye output (Usually 9-24 volt sourcing or
sinking depending on the photoeye.) all you would need is some divider
circuits to produce your timebase signal for a clock. Nixie, numitron etc.
See WIkipedia Balance Wheel. A good 17-23 jewel watch movement sitting in
one position a constant temperature can be very accurate.
Tim
When I bought a Bulova Accutron tuning-fork watch in 1990, I wanted to
see just how accurate it was. So I bought an HP5245L Nixie-tube
frequency counter from the local surplus shop, built a 300 Hz bandpass
filter, and connected a microphone placed against the back of the watch
to the counter through the filter.
It worked quite well.
Wit ha bit of scaling and divide-by trickery, one could convert that
arrangement into a Nixie clock with tuning-fork accuracy instead of the
ovenized quartz crystal built into the HP counter.
Why one would want to is another question.
--
David Forbes, Tucson AZ
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