[time-nuts] How did they distribute time in the old days?

Tom Van Baak tvb at LeapSecond.com
Thu Oct 15 10:32:55 EDT 2015

Nick Sayer writes:
> The WU standard time service goes back further than the turn of the 20th century. It started in 1870.

See also: http://leapsecond.com/history/usno.htm

> I’ve always wanted to get my hands on one of those clocks and come up with a circuit to recreate
> the synchronization signal for it, probably with a Raspberry Pi running ntpd and a big ol’ MOSFET.
> The problem is that at this point, those clocks are quite expensive once they’re reconditioned.

You will find lots of these auto-setting self-winding clocks on eBay. Some are very reasonably priced.

There's a bunch of clock guys out there who play with these and you'll find circuits and information with a google search for words like self-winding clock company or SWCC or Western Union USNO and so on. Start with:


Mitch's (www.telechron.com) and Ken's (www.kensclockclinic.com) sites are superb.
Also, for a screen full of irresistible SWCC photos, try this:

> My understanding (perhaps incorrect) was that the sync pulse was once daily and, as you said,
> would cause the hands to “snap” to 12. The trailing edge of the pulse was synchronized and would
> release the clock to operate normally.
> That they had something as accurate and widespread as it was so early is astonishing.

Oh, Padawan, that's just the tip of the iceberg when it comes to the deep and fascinating history of precise timekeeping.


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