Redding telegraph relay
date: label: date made
content: 1885
name: label: maker
content: Jerome Redding & Co.
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: This 1880s relay made by Jerome Redding & Co. of Boston features an unusual adjusting mechanism for the armature spring. Relays required adjustment to compensate for changing conditions on the line. Older designs used adjusting screws and springs to change the position of the coils and the sensitivity of the armature–a tricky task since the recommended armature action was about 1/32" (less than 1mm). The spring adjustment post on this relay is set on a sliding rail on the base and the entire post moves back and worth as needed.
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
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content: Telegraph Relays & Repeaters
creditLine: label: Credit Line
content: from Tufts University, Departments of Electrical Engineering and Physics
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.328044
label: catalog number
content: 328044
label: accession number
content: 270107
objectType: label: Object Name
content: relay
label: Object Name
content: telegraph relay
physicalDescription: label: Physical Description
content: brass (overall material)
label: Physical Description
content: wood (overall material)
label: Physical Description
content: plastic (overall material)
label: Physical Description
content: steel (overall material)
label: Measurements
content: overall: 4 in x 9 in x 4 1/4 in; 10.16 cm x 22.86 cm x 10.795 cm