Reed Switch Level Sensor Circuit

A reed switch is a sensor that closes the circuit in the presence of a magnetic field.

Reed switch level sensor circuit.

The contacts are usually normally open closing when a magnetic field is present or they may be. Magnetic float level sensor is composed of a reed switch a precision resistor and a single chip microcomputer circuit. The reed switch is an electrical switch operated by an applied magnetic field it was invented at bell telephone laboratories in 1936 by walter b. Reed switches and reed sensors are used along with resistors or special reed sensors with integrated resistor to give out a potentiometric feed back across two outputs as a foamed magnetic float moves along the pcb s length.

Some fluid level sensors in clothes washing machines and dishwashers use floating magnets that bob up past reed switches to switch off the valves when enough water is inside. Reed sensors can be used in many applications where contactless on off is required. However reed switches can be fragile to use directly hence this module can make it easier to handle and mount the sensor in various applications. In its simplest and most common form it consists of a pair of ferromagnetic flexible metal contacts in a hermetically sealed glass envelope.

Reed switches are sometimes also fitted to the spinning arms of dishwashers to detect when they jam and in the thermal cut offs in electric showers to stop the water.