Hi: The Western Union clocks made by the Self Winding Clock Co. have a provision for hourly synchronization of the hour, minute and second hands using a pulse. Since there were many thousands of these in service they are constantly on eBay. See: http://www.prc68.com/I/SWCC.shtml#Sync http://www.prc68.com/I/SWCC2.shtml#SC
When they were used in government buildings, banks, jewelry stores, etc. the line voltage was 120 VDC and the current was adjusted to 250 ma with a variable resistor. Note that the time constant of an LR circuit is proportional to L/R so raising the voltage allows adding resistance speeding up the circuit. This is mandatory in teletype circuits and makes a big improvement in the operation of the synchronizing circuit for a clock or operation of a slave clock. Since it's only one pulse per hour I've started looking into using a free power supply that runs on a single AA cell. The problem with these is that the voltage is about 300 VDC, but that may be OK if current limited to 250 ma (abut 1200 Ohms). See: http://www.prc68.com/I/LED.shtml#SUCFBO -- Have Fun, Brooke Clarke http://www.prc68.com _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
