reed relay

One or more reed switches inside a coil is a reed relay.

Millions of reed relays were used in telephone exchanges in the 1970s and 80s.

Mercury-wetted reed relays are sometimes used, especially in high-speed counting circuits.

A few million reed relays were used from the 1930s to the 1960s for memory functions in Bell System electromechanical telephone exchanges.

A relay, usually a reed relay, has its contacts coated with a small quantity of mercury.

This gives the low bounce advantage of mercury, although the current capacity is still limited to broadly that of the original reed relay.

They would then run this compass along outside of the reed relays and when a relay was operated the needle would move back to North.

There is therefore a 5x5 switching matrix of reed relays, which constituted the A-switch.

A reed relay is another example of the attraction principle.

A reed relay is a reed switch enclosed in a solenoid.