Miniature Bunnell main-line telegraph relay

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 miniature relay was made by the donor as a replica of a commercial main-line relay made J. H. Bunnell & Company. Ways made an operational set of miniature telegraph pieces that included this relay.
Currently not on view
Object Name
telegraph relay
date made
ca 1900
C. I. Ways
Physical Description
wood (overall material)
metal (overall material)
brass (overall material)
plastic (overall material)
overall: 1 3/4 in x 3 in x 2 in; 4.445 cm x 7.62 cm x 5.08 cm
ID Number
catalog number
accession number
See more items in
Work and Industry: Electricity
Telegraph Relays & Repeaters
Data Source
National Museum of American History, Kenneth E. Behring Center


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