Reed Switches

A reed switch is an electrical switch operated by an applied magnetic field. The basic reed switch is comprised of two ferromagnetic nickel-iron wires and a hermetically sealed glass capsule. The two wires are formed into 'reeds' by flattening one end. The reeds are aligned with a small overlap and then sealed in a glass capsule. The reed switch is activated by an electromagnetic coil or by bringing a magnet close to the reed switch. Magnetism attracts the reeds. Once the magnet is pulled away from the switch, the reed switch returns to its original position. No power is needed to activate the reed switch. Reed switch types include Normally Open (Form A), Normally Closed (Form B) and Change Over (Form C). Form A is a Single Pole, Single Throw, Normally Open Switch (SPST NO). Form B is a Single Pole, Single Throw, Normally Closed Switch (SPST NC). Form C is a Single Pole, Double Throw, Change Over Switch (SPDT CO). A reed switch is an integral part of a reed sensor. Typical applications can be found in refrigerators/freezers, dish washers, washing machines, rice cookers, coffee makers, vacuum cleaners and vending machines.