There are two sensor choices, reed and Hall-effect switches. They have many similarities but also significant differences, explains Martin Reizner. Demand for reed switches has risen significantly in ...

The reed relay was invented in 1936 by Bell Telephone Laboratories. Since that time, it has gradually evolved from very large, relatively crude parts to the small, ultra-reliable parts we have today.

Reed relays contain a reed switch, a coil for creating a magnetic field, an optional diode for handling back EMF from the coil, and an encapsulating package with connection terminals. In many ways, a ...