Merchant, F. W. (Francis Walter), 1855-1937, Chant, Clarence Augustus, 1865-1956 · Toronto : Copp Clark · leaf 221
THE TELEGRAPH RELAY 213 … Fig. 25-1 —Telegraph relay. 254. The Telegraph Relay. The relay is an instrumentfor closing automatically a local circuit in an office, whenthe current in the main circuit,on account of the great resistanceof the line, is too weak to workthe sounder. It is a key workedby an electromagnet instead…
Physics
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