[time-nuts] NTP Clock suggestions?

Brooke Clarke brooke at pacific.net
Thu May 30 14:10:32 EDT 2013

Hi Chuck:

The Western Union Self Winding Clock Co. clocks that were used in radio stations had second hands, unlike the prior 
clocks that were used in banks, railroad stations, etc. that only had hour and minute hands.

See figures 4 and 6 at the top of the page:

I suspect that the accuracy was less than one second.  The electromagnet was applied at hh:59:59 and released at hh+1:00:00.

Have Fun,

Brooke Clarke

Chuck Forsberg WA7KGX N2469R wrote:
> One station I worked for in the 60s had a Western Union clock that was synchronized hourly.
> If you watched it you could see the hands twitch at the top of the hour.
> On 05/28/2013 05:04 PM, Al Wolfe wrote:
>>     I actually built a contraption like this back in the 1970's. As chief engineer at a couple of automated radio 
>> stations, I was tasked with keeping the network-joiner clocks accurate. It sounded really sloppy to have dead air or 
>> to up-cut the network. These clocks were 60 htz synchronous motors that ran cam switches. Real PITA to adjust. 
>> Unfortunately, the utility power drifted up and down frequency wise, a few seconds a week. Long term was pretty good, 
>> though.
>>    I built a 10 mhz crystal oscillator and divided it down to 50 htz. with a string of 7490 decade dividers. Then 
>> built a 600 htz VCO out of a pair of 7400 NAND gates biased linearly. Divided the 600 by 12 with a 7492 and PLLed the 
>> 50 htz results with the precision 50 htz to control the 600 htz. Then divided the 600 by 10 in another 7490 to get 60 
>> htz. Low passed this 60 htz square wave so it kind of looked like a sine wave and drove a small PA amplifier (pair of 
>> 6L6's I think.) This drove a 6.3 V filament transformer backwards to supply the 120 VAC to power the synchronous 
>> clock motors as well as some wall clocks.
>>    A kluge but it worked great. Every one was happy, the owner, the GM, the PD, and me because they got off my back 
>> about sloppy timing with the net joiner. About once a month or so I would fire up the old SP600 in the rack and check 
>> zero beat  of the 10 mhz timebase against WWV with Lissijous figures on an oscilloscope. (Used the VFO of the SP600 
>> do drive a cathode follower into a mixer so the the scope was looking at the low IF frequency. Zero beat was very 
>> obvious and the stability of the receive was not an issue.)
>>    This thing ran fine for at least ten years. The stations changed formats so they didn't need it any more. Probably 
>> wound up in a dumpster.
>> Al,  retired  (A.K.A. K9SI)
>>> albertson.chris at gmail.com said:
>>>> OK, the LOWEST cost option I can think of for driving an analog clock with
>>>> millisecond accuracy.   Buy a normal AC powered clock that uses a
>>>> synchronous AC motor that runs off the 60Hz AC power, not a battery powered
>>>> clock.  Then have your NTP disciplined computer generate a 60Hz audio sine
>>>> wave.  Amplify the sine wave to 12 volts then use a small 12:120 volt
>>>> transformer to step up to 120VAC.  ...
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.

More information about the time-nuts mailing list