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 tran ...
, a transmitter which repeats or transponds the signal of another
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Microwave radio relay
Microwave transmission is the transmission of information by electromagnetic waves with wavelengths in the microwave frequency range of 300MHz to 300GHz(1 m - 1 mm wavelength) of the electromagnetic spectrum. Microwave signals are normally lim ...
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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. Some ...
, 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
The Saturn Relay is a minivan that was made by General Motors. It was introduced for the 2005 model year, and was built alongside badge engineered variants, the Buick Terraza, the Chevrolet Uplander, and the Pontiac Montana SV6 in Doraville, Ge ...
, 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 Race track, racecourse or performing a certain action. Relay races take the form of professional races and amateur games. Relay races are common in runni ...
, 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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