Bistable Reed Switches
A bistable reed switch, also known as a latching reed switch, uses magnetic fields to open and close electrical contacts. The switch can be in a normally open (N.O.) or normally closed (N.C.) state.
How it works
- A partially magnetized permanent magnet brings the switch contacts closer together, but they remain open.
- A second magnet with an aiding field closes the contacts.
- The contacts remain closed until the second magnet is brought close again, but with a reversed magnetic field.
Why it's useful
- Bistable reed switches are low-cost, passive sensors that don't require a power source.
- They're ideal for battery-powered devices and other power-critical applications.
- They're commonly used to confirm that a target is in the correct location.
How it's made
- Bistable reed switches contain one or more internal reed switches and permanent magnets.
- The reeds are ferromagnetic, usually made from an iron-based alloy like nickel and iron.
- The reeds are housed in a hermetically sealed glass bubble or envelope.