Bunnell box telegraph relay
name: label: maker
content: J. H. Bunnell & 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: Box relays like this unit made by J. H. Bunnell & Co., were special relays most often used by linemen or station operators for testing purposes or where a local battery was not available. The covering box acted as a resonator that amplified the sound of the relay’s light-weight armature, making the signal audible without a sounder. The relay includes a built-in telegraph key and a mark indicating that it was used by the B & O Railroad.
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.294351.011
label: accession number
content: 294351
label: catalog number
content: 294351.011
objectType: label: Object Name
content: box relay
label: Object Name
content: telegraph relay
physicalDescription: label: Physical Description
content: wood (overall material)
label: Physical Description
content: metal (overall material)
label: Physical Description
content: plastic (overall material)
label: Physical Description
content: brass (overall material)
label: Measurements
content: overall: 4 in x 11 5/8 in x 5 1/4 in; 10.16 cm x 29.5275 cm x 13.335 cm