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

Reed Sensor

Reed sensors

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

Reed Sensor (Wikipedia)

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. The contacts are usually 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. It somewhat resembles part of some reed plants. The term "reed" may also include the external wire lead as well as the internal part.

(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 common example of a reed switch application is to detect the opening of a door or windows, for a security alarm.

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