Bi-Stable / Latching Reed Sensors

A latching reed sensor is an extremely low power solution. These work very well in battery powered devices and other power critical applications. Latching or bi-stable sensors use magnetic biasing to open and close their contacts. The sensor contains one or more internal reed switches and/or permanent magnets. The internal permanent magnet moves the reed switch contacts closer together. But still the contacts remain in the open state. Because the magnet is only partially magnetized. While an external magnet opens and closes the switch by reversing the magnetic field. Hence the latching function. The contacts remain in their normally open or closed state until the magnetic field is changes yet again.