OT: Digital Watch Recommendations?

From: Kent Borg <kentborg_at_borg.org>
Date: Tue Aug 6 08:34:00 2002

On Tue, Aug 06, 2002 at 12:21:12AM +0100, Tony Duell wrote:
> Can I conclude from this that the clock movement is relatively
> conventional, with (say) an anchor escapement.

I am afraid I know little about clocks. I know a fair amount about
time, but that is different.

> My next question may sound silly : Was it designed to keep good time?

I think so. The pendulum is adjustable and there is a notice saying
how many seconds each turn is worth. Also, the synchronization pulse
can pull the seconds forward of back, I'd say it is happy to adjust
within +/- 10 seconds. (Honestly, I can't remember now whether the
minute hand also zeros on the pulse--I think so.)

After I had it repaired I was ajusting it and for a while it was
running *perfectly*. Or at least better than a quartz watch. It was
as though I was sending sync pulses. It ran that way for well over a
week.

> There is one part of this mechanism I can't help telling you about. [...]

Interesting.

> Hnng on, what drives what here? Is it a convenional anchor escapement
> where the 'scape wheel is driven from the spring remontoir, controlled
> by the pendulum, or is it an electrically maintained pendulum with a pawl
> and ratchet wheel that drives the hands? I thought the former, but this
> part of the description worries me.

Now you are getting beyond my knowledge of the terminology. Sounds
like some of each, but I wonder whether that makes sense. "pawl and
ratchet wheel" sounds like a good description of what is there; the
wheel has kinda a sawtooth to it and this shovel-looking thing pulls
back, drops down to the next tooth, swings the other way shoving the
wheel a seconds-worth, then swings back again for another go. The
edge of this shovel (or possibly "prawl") is what got worn down. It
wasn't shoving the wheel quite far enough.

So what propels the pendulum? It occures to me that I don't know. I
know that the electricity is there to wind a spring. I'll have to see
if I can see inside. (I think I once removed the hands and face to
see all this, but I am reluctant to keep doing that and will look from
the side with a bright light.)

> I suspect you could have done the repairs yourself...

It looked to me like there was metal missing from where it once was
and again needed to be. Buying a new part seems unlikely, making a
new one seems difficult, and repairing the old one seems a bit magical
too. Is it really that easy?


Seeing another e-mail that there are a bunch of these in the 'tty
warehouse, I think you might want to visit NJ soon and get one.


-kb, the Kent who was thinking yesterday that he would also like one
of those digital clocks with the flipping metal numbers.



P.S. I have also thought it would be neat make a 120 V AC supply with
a precise time base (referenced back to the Naval Observatory I
suppose) for driving a nice big synchronous motor clock with a
beautiful, smooth, sweep second hand that would be right on the
button. Are synchronous motors willing to run without damage on the
stepped sin wave put out by cheap 12v-to-120v inverters? One of those
might make a good starting point.
Received on Tue Aug 06 2002 - 08:34:00 BST