Bunnell telegraph repeater patent model
date: label: date made
content: 1867
name: label: maker
content: J. H. Bunnell & Co.
notes: label: Description
content: Telegraph repeaters 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, limiting the distance a message could travel. Repeaters remedied that problem by detecting a weak signal and using a local power source to re-energize and re-transmit the signal down the line.
label: Description
content: This model was submitted to the U.S. Patent Office by inventor Jesse Bunnell of New York City along with his patent application. On 26 January 1868, he received patent #73774 for his "Improvement in Telegraph-Repeaters." In their 1877 review of telegraph equipment, Charles Davis and Frank Rae reported that in Bunnell's repeater, “the arrangement of the main circuits ... is exactly like that of an ordinary button repeater.” However, instead of a person operating the lever to engage the repeater, the switching was made automatic thru the use of “two governor magnets.” The governor magnets were wound with a much finer wire than that used in the sounders so the resistance, and hence the magnetic field, differed between the two and enabled the automatic switching to operate.
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
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.251258
label: catalog number
content: 251258
label: accession number
content: 48865
label: patent number
content: 73774
objectType: label: Object Name
content: telegraph set
label: Object Name
content: telegraph relay
label: Object Name
content: telegraph repeater
label: Object Type
content: Patent Model
label: Other Terms
content: telegraph relay; Telegraphy
physicalDescription: label: Physical Description
content: brass (overall material)
label: Physical Description
content: wood (overall material)
label: Physical Description
content: cloth (overall material)
label: Physical Description
content: steel (overall material)
label: Physical Description
content: copper (overall material)
label: Measurements
content: overall: 3 1/4 in x 12 in x 11 7/8 in; 8.255 cm x 30.48 cm x 30.1625 cm