[D1] A reed switch using contact detail
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[D1] (from top) Single-pole reed switch, 4-pole reed switch and single-pole reed relay. Scale in centimeters.
Reed switch
Reed switch
[1] The reed switch is an electromechanical switch operated by an applied magnetic field. It was invented in 1922 by professor Valentin Kovalenkov at the Petrograd Electrotechnical University, and later evolved at Bell Telephone Laboratories in 1936 by Walter B. Ellwood into the reed relay. In its simplest and most common form, it consists of a pair of ferromagnetic flexible metal contacts in a hermetically sealed glass envelope.
[1]
[1] The usual symbol for a reed switch.
[1] The contacts are often normally open, closing when a magnetic field is present, or they may be normally closed and open when a magnetic field is applied. The switch may be actuated by an electromagnetic coil, making a reed relay, or by bringing a permanent magnet near it. When the magnetic field is removed, the contacts in the reed switch return to their original position. The "reed" is the metal part inside the reed switch envelope that is relatively thin and wide to make it flexible, resembling the reed of a musical instrument. The term "reed" may also include the external wire lead as well as the internal part.
A usual example of a reed switch application is to detect the opening of a door or windows, for a security alarm.[3]
Operation
Operation
[2] A reed switch consists of 2 flat ferromagnetic reeds sealed in an inert atmosphere in a glass capsule. In the presence of a magnetic field the reeds are attracted to each other and close to complete the magnetic and electric circuit. Our reed switches are manufactured to the highest standards ensuring long life and consistent performance. Reed Switches are available in a wide range of formats and contact ratings.
References
References
[1] Wikipedia
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