Repeater for Farmer duplex telegraph

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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.
This repeater was made by Charles Williams, Jr. of Boston and used in experiments by Moses Farmer. Our records indicate that this repeater was used as evidence in suit against Western Union Telegraph Company by Farmer.
Currently not on view
date made
ca 1878
Charles Williams, Jr.
Physical Description
brass (overall material)
wood (overall material)
steel (overall material)
plastic (overall material)
overall: 4 1/2 in x 9 3/4 in x 6 7/8 in; 11.43 cm x 24.765 cm x 17.4625 cm
ID Number
catalog number
accession number
Credit Line
from Sarah J. Farmer
See more items in
Work and Industry: Electricity
Telegraph Relays & Repeaters
Data Source
National Museum of American History


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