Reed switch
A reed switch is an electrical switch that changes its position via magnetism. It is turned on by bringing a magnet near to the switch. Once the magnet is pulled away from the switch, the reed switch will go back to its original position. If the magnet is an electromagnet, it is a reed relay. The reed switch was invented at Bell Telephone Laboratories in 1936 by W. B. Ellwood.
Reed Switch Media
(from top) Single-pole reed switch, four-pole reed switch and single-pole reed relay. Scale in centimeters.
Reed switch, contact detail.
Commonly-used circuit symbol
Operation of the reed switch
A reed relay from a TXE-3 telephone exchange
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