Clock Electronic 1A System

This was the last in-house design of the master clock system by British Telecom (Successor to the GPO and Post Office)
It produced all the pulses formerly done by the Clocks No.s 36, 46, 62A & 70A plus it had additional facilities including synchronising with the speaking clock (TIM) every 10 seconds, the programming of change over between winter and summer time up to 7 days in advance and quartz timer accuracy.

What they lacked in old world charm of polished wood, brass pendulums and living sound, they made up for with unparalleled accuracy and the ability to be left unattended for long periods of time.

Click here to download the system handbook including diagrams. (About 5.3Mb) This document was kindly provided by Brett Oliver.

This system is also mentioned in ISIS TXA/MEP/A071 twice yearly time change