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The Relay

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  P-371

2025-12-10

376

is an electromagnet of high resistance in series with the main line. Its function is to make and break contact in the local circuit which controls the sounder. It has nothing whatever to do with strengthening the current in the sounder, which gets its current from the local battery only. When a current from the main line passes through the relay, its armature is attracted, current from the local battery passes through the sounder circuit, the sounder armature is attracted and makes a loud click from which the message is read. The way in which this is done will be seen by referring to Fig.1. The relay is wound with a great many turns of fine wire, so that the small main current may be able to magnetize it.