again would not re-energize the relay. Button Β would need to
be pushed again to re-energize the relay.
Bell
and call systems
These systems and variations of them are widely used in hotels and
hospitals. Diagram 77 shows a basic system.
When a remote push button is operated, its associated relay is
energized and an indicator flag drops into a window in the indicator
board. As the bell is in series with al ...
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