What is relay?

  • (noun): Electrical device such that current flowing through it in one circuit can switch on and off a current in a second circuit.
    Synonyms: electrical relay
    See also — Additional definitions below


A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another. Relays were used extensively in telephone exchanges and early computers to perform logical operations.

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Some articles on relay:

Relay - History
... The relay was invented in 1835 by American scientist Joseph Henry in order to improve his version of the electrical telegraph, developed earlier in 1831 ... It is claimed that the English inventor Edward Davy "certainly invented the electric relay" in his electric telegraph c.1835 ... A simple device, which we now call a relay, was included in the original 1840 telegraph patent of Samuel Morse ...
DWTV - Shortwave Relay Stations - Relay Stations Leasing Transmitter Time To DW
... DW leases time on the following relay stations Novosibirsk, Russia Irkutsk, Russia Alma Ata, Kazakhstan Skelton, United Kingdom Woofferton, United Kingdom Kranji, Singapore (BBC ...
Davian Clarke - Achievements
... Venue Position Event Notes Representing Jamaica 1996 Summer Olympics Atlanta, Georgia 3rd 4x400m relay 1997 World Championships Athens, Greece 3rd 4x400m ...
Dwight Thomas
... for Jamaica Olympic Games Gold 2008 Beijing 4×100 m relay World Championships Gold 2009 Berlin 4×100 m relay Pan American Games Bronze 1999 Winnipeg 4×100 m relay CAC Junior Championships (U20) Gold 1998 George ...

More definitions of "relay":

  • (verb): Pass along.
    Example: "Please relay the news to the villagers"
  • (noun): The act of relaying something.
  • (verb): Control or operate by relay.