A
relay
A relay
Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts
An automotive-style miniature relay with the dust cover taken off
A relay is an electrically operated switch ...
is an electric switch operated by a signal in one circuit to control another circuit.
Relay may also refer to:
Historical
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Stage station
A stage station or relay station, also known as a staging post, a posting station, or a stage stop, is a place where exhausted horses could be replaced by fresh animals, since a long journey was much faster without delays when horses needed rest ...
, a place where exhausted horses being used for transport could be exchanged for fresh ones
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Cursus publicus
The ''cursus publicus'' (Latin: "the public way"; grc, δημόσιος δρόμος, ''dēmósios drómos'') was the state mandated and supervised courier and transportation service of the Roman Empire, later inherited by the Eastern Roma ...
, a courier service in the Roman Empire
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Relay league
A relay league is a chain of message forwarding stations in a system of optical telegraphs, radio telegraph stations, or riding couriers. Early 19th century methods of this type evolved into the electrical telegraph networks of the mid-to-late 19t ...
, a chain of message-forwarding stations
Computer networking
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BITNET Relay, a 1980s online chat system
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Mail relay, a server used for forwarding e-mail
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Open mail relay
An open mail relay is a Simple Mail Transfer Protocol (SMTP) server configured in such a way that it allows anyone on the Internet to send e-mail through it, not just mail destined to or originating from known users. This used to be the default con ...
, such a server that can be used by anyone
Other telecommunication
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Relay (satellite)
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Broadcast relay station
A broadcast relay station, also known as a satellite station, relay transmitter, broadcast translator (U.S.), re-broadcaster (Canada), repeater ( two-way radio) or complementary station (Mexico), is a broadcast transmitter which repeats (or tr ...
, a transmitter which repeats or transponds the signal of another
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Microwave radio relay
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Relay channel In information theory, a relay channel is a probability model of the communication between a sender
A sender was a special type of circuit in 20th-century electromechanical telephone exchanges which registered the telephone numbers dialed by the s ...
, in information theory, a communications probability modeling system
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Telecommunications Relay Service
A telecommunications relay service, also known as TRS, relay service, or IP-relay, or Web-based relay service, is an operator service that allows people who are deaf, hard of hearing, deafblind, or have a speech disorder to place calls to st ...
, a telephone accessibility service for the deaf
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Repeater
In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Som ...
, an electronic device that receives and retransmits a signal
Automobiles
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Citroën Relay, a marketing name for the Fiat Ducato van
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Saturn Relay, a 2005-2007 minivan
Other uses
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Relay (shop)
Relay is a chain of newspaper, magazine, book, and convenience stores, mostly based in train stations and airports. It is owned by Lagardère Travel Retail, a subsidiary of Lagardère Group.
Its heaviest concentration is in France, but it also ...
, a France-based chain of convenience stores
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Relay (company), a peer-to-peer political texting platform
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"Relay" (song), 1972, by The Who
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Relay bid
In contract bridge, a relay bid is a conventional bid that usually has little or no descriptive meaning but asks partner to describe some feature of his hand. A relay is often the cheapest bid available but need not be. Stayman and Blackwood ...
, in contract bridge
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Relay race
A relay race is a racing competition where members of a team take turns completing parts of racecourse or performing a certain action. Relay races take the form of professional races and amateur games. Relay races are common in running, oriente ...
, completed in parts by several participants of a team
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Relay neuron, in anatomy
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Relay box, a piece of postal infrastructure.
See also
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Retransmission (disambiguation)
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