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.

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. The contacts are usually normally open closing when a magnetic field is present or they may be. How to use magnetic sensor and reed switch in projects a magnetic field from an electromagnet or a permanent magnet will cause the reeds to attract each othe. 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.

The pcb tracks can be designed in such a way that a full tank gives high resistance and an empty tank gives low resistance or vice versa. 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. When the magnetic force line of the magnetic float acts on a certain position of the liquid level gauge the reed switch in that position is closed. Reed sensors can be used in many applications where contactless on off is required.

In its simplest and most common form it consists of a pair of ferromagnetic flexible metal contacts in a hermetically sealed glass envelope.