Foote Pierson "pony" telegraph relay

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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.
So-called “pony” relays like this unit made by Foote, Pierson & Co., serviced private lines and shorter branch circuits. The resistance of a given pony relay varied depending on the length of the circuit. This 20 ohm pony relay would have been used on circuits up to about 15 miles in length.
Location
Currently not on view
date made
ca 1900
maker
Foote, Pierson & Co.
Physical Description
wood (overall material)
cast iron (overall material)
brass (overall material)
Measurements
overall: 2 1/2 in x 6 1/2 in x 3 1/2 in; 6.35 cm x 16.51 cm x 8.89 cm
ID Number
EM.222132
catalog number
222132
accession number
41949
Credit Line
from Foote Pierson & Co.
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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