Reed Relays and
Electronics India Limited
Manufacturer of Reed Switches, Reed Sensors and Reed-based products
Reed Relays and Electronics India Limited Incorporated in 1971
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Reed Sensor

A reed sensor is a device built using a reed switch with additional functionality or features, for example, to withstand higher shock, easier PCB mounting, additional intelligent circuitry, biased contact states, etc.

Reed Sensor (Wikipedia)
Reed relay and reed switches
Showing the contacts clearly
Commonly used circuit symbol
Operation of the reed switch

The reed switch (sometimes also known as Herkon) is an electrical switch operated by an applied magnetic field. It was invented at Bell Telephone Laboratories in 1936 by W. B. Ellwood. It consists of a pair of contacts on ferromagnetic metal reeds in a hermetically sealed glass envelope. The contacts may be normally open, closing when a magnetic field is present, or normally closed and opening when a magnetic field is applied. The switch may be actuated by a coil, making a reed relay, or 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.

An example of a reed switch's application is to detect the opening of a door, when used as a proximity switch for a burglar alarm.

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