main-line telegraph relay
date: label: date made
content: 1880
name: label: maker
content: Western Electric
notes: label: Description
content: Telegraph relays amplified electrical signals in a telegraph line. Telegraph messages traveled as a series of electrical pulses through a wire from a transmitter to a receiver. Short pulses made a dot, slightly longer pulses a dash. The pulses faded in strength as they traveled through the wire, to the point where the incoming signal was too weak to directly operate a receiving sounder or register. A relay detected a weak signal and used a battery to strengthen the signal so that the receiver would operate.
label: Description
content: “Main line” relays like this Western Electric unit were one of the most common types of relay and, as seen in this piece, were typically made with a resistance of 150 ohms. As the name suggests, main line relays served on major intercity circuits several hundred miles long. Better known for their Bell System telephone equipment, Western Electric manufactured a wide range of electrical devices.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
label: See more items in
content: Communications
label: See more items in
content: Telegraph Relays & Repeaters
creditLine: label: Credit Line
content: from Western Union Corporation
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.331933
label: accession number
content: 294351
label: catalog number
content: 331933
label: collector/donor number
content: 04-23
objectType: label: Object Name
content: main-line relay
label: Object Name
content: telegraph relay
physicalDescription: label: Physical Description
content: wood (overall material)
label: Physical Description
content: brass (overall material)
label: Physical Description
content: steel (overall material)
label: Physical Description
content: iron (overall material)
label: Physical Description
content: plastic (overall material)
label: Measurements
content: overall: 4 1/8 in x 8 7/8 in x 4 7/8 in; 10.4775 cm x 22.5425 cm x 12.3825 cm