Bunnell duplex telegraph relay

Description
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.
This relay is a model from the early 20th century and was designed for duplex lines that could carry two messages simultaneously on the same wire. The unit bears an inspection stamp "N.Y.R.S. 9 24" indicating that it was serviced at Western Union's New York Repair Shop in September 1924.
Location
Currently not on view
Object Name
telegraph relay
duplex telegraph relay
date made
ca 1920
maker
J. H. Bunnell & Co.
J. H. Bunnell
Physical Description
wood (overall material)
brass (overall material)
steel (overall material)
iron (overall material)
plastic (overall material)
Measurements
overall: 4 in x 8 1/4 in x 4 3/4 in; 10.16 cm x 20.955 cm x 12.065 cm
ID Number
EM*331390
catalog number
331390
accession number
294351
collector/donor number
100-027
See more items in
Work and Industry: Electricity
Communications
Telegraph Relays & Repeaters
Data Source
National Museum of American History, Kenneth E. Behring Center

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