Jim,
If your Western Union clock is similar to the type used in broadcasting,
you might want a setting pulse that starts at 59:59 and ends at 00:00 . The
reason is that at 59:59 the magnet pulls the second hand to the 12 o'clock
position and releases it on the hour. The one-second difference might seem
trivial, but it's actually about three words for an announcer beginning a
network broadcast.
When Western Union got out of the clock business in the late 1970s
(following a technician strike where the master clocks were ignored and service
deteriorated) the company I worked for purchased the clock installation from
Western Union (for $75 per clock as I remember) and we installed a digital
master system. The Western Union clocks were all connected in series and
driven as a constant-current teletype type loop. We had wire-wrap logic
panels associated with the digital master time system. Signals for the W. U.
clocks, for alerting control rooms before newscasts, starting recordings,
etc., were implemented by simply adding chips, DIP relays, 14/16-pin boards
with components such as timing capacitors, and wire-wraping the underside
pins. I/O was implemented with those 14 and 16-pin DIP connectors on one
end of ribbon cables -- the other ends being terminated on barrier strips on
rack wall panels.
Bruce
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