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Sparks 14th May 2022 8:12 pm

School master and slave clocks
I attended secondary school in Leeds in the 1980s. Throughout the school and library complex (finally finished building in 1975), there were identical wall clocks. I think they had a white surround, brushed metal face and black numerals with black minute and hour hands and a red second hand. Occasionally, they worked and were accurate but mainly, they were stopped. Can anyone name a likely manufacturer or supplier ? The external buzzer announcing break and lunchtime was Gent and I think the fire alarms were too.


M0FYA Andy 14th May 2022 10:24 pm

Re: School master and slave clocks
Gents were a major manufacturer of master/slave clock systems, and equipped many schools. Their 'Pulsynetic' sytem was still being supplied into the 1970's, after which various electronic master clocks were introduced in place of the Pulsynetic 'time transmitter' for newly installed sytems.
There are various varieties of Pulsynetic system, the classic one being series-connected loops of slaves, impulsed every 30 seconds, but also 24v parallel systems. The later electronic masters more commonly used alternating polarity impulses every minute.
Slaves with a seconds hand could be impulsed every second, but some used a mains-powered synchronous motor to drive the seconds hand.

Its a complicated subject with numerous possibilities!


Sparks 15th May 2022 8:01 am

Re: School master and slave clocks
Thanks Andy. The last time I remember any of the clock hands moving was when the minute and hour hands started to tick by every second! That might have been some kind of reset or somebody trying to get them working. As I said, they didn't usually work at all.

lesmw0sec 15th May 2022 8:25 am

Re: School master and slave clocks
We had a smilar system at Winfrith (UKAEA) which synchroised the clocks. Another feature was a relay box in the labs, from which timed pulses from the master clock could be used for testing/experiments.

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