Magnetic Reed Switch (Magnetic Reed Sensor) 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 ferrous 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.

It can be used to make a float sensor. A float sensor is a device used to detect the level of liquid within a tank. The switch may be used in a pump, an indicator, an alarm, or other devices. Magnetic float sensor is an electromagnetic ON/OFF switch. It helps to sense the level of water present in the overhead tank or sump. These sensors has a permanent magnet in the float. The Switch is present in the white stem of the sensor. As the float rises or falls with level of water in the tank, the switch gets activated by the magnet in the float, thereby the signal which is obtained from the sensors is used along with the water level controllers for controlling the motor pump.
Round Magnet - Outer Diameter - 17 mm, Inner Diameter -7.3mm, Height -2.3 mm

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