A dictionary of electrical words, terms and phrases (1898)
Houston, Edwin J. (Edwin James), 1847-1914 · New York, The W. J. Johnston company · leaf 185
of a bell or other alarm, or, it may givea silent indication. Drop, Annunciator, Automatic A drop for an annunciator, which on the closingof a circuit, falls and holds the circuit closeduntil the drop is raised. Drop, Annunciator, Gravity —A drop for an annunciator, acted on by gravitywhen released… … The automatic drop is especially applicable toburglar alarms. On the opening of a door orshutter, the closing of the circuit moves thearmature of an elec-tro - magnet, and,by the falling of adrop, closes the cir-cuit and holds itclosed until me-chanically openedby the replacing ofthe drop.…
Electricity · Electrical engineering
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