[time-nuts] [Summary] HP 115CR Clock Powerup / Documentation

Bill Hawkins bill.iaxs at pobox.com
Fri Dec 23 22:29:22 EST 2016

Got a 113BR clock many years ago because it looked like the clock in the
Smithsonian. Used a 103 precision OCXO for the source.

It is noisy. That's part of why it has a heavy metal case. I expect that
a rebuilt stepping motor might have been quieter. I kept it in a larger
wooden box lined with R19 fiberglass insulation. I used an insulated
wooden front door held by magnetic catches to close the box, had to
remove the door to see it.

The manual reset is a feature. If the clock stops for any reason, it
stays stopped. If it restarted by itself it would authoritatively show
you the wrong time. A battery and float charger are required if you want
to see how much it varies in a year.

If all you want is a technically attractive clock, talk to a watchmaker
about driving it with a synchronous clock motor. Or do your own 10 Hz
stepping motor (or whatever gear ratio is easy).

Best of luck
Bill Hawkins

-----Original Message-----
* Divider circuits need to be manually started using internal switches
[snip] Similarly the motor must be manually started.

"These clocks are not a lot of fun to live with.  They sing along quite
loudly at 1KHz."

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