Manhattan Electric pony 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.
So-called “pony” relays like this unit made by Manhattan Electric Supply Co., serviced private lines and shorter branch circuits. The resistance of a given pony relay varied depending on the length of the circuit. This 10 ohm pony relay would have been used on circuits up to about 7 miles in length.
Currently not on view
Object Name
telegraph receiver
telegraph relay
Manhattan Electric Supply Co.
Physical Description
wood (overall material)
metal (overall material)
brass (overall material)
cloth (overall material)
overall: 3 in x 6 1/2 in x 3 1/2 in; 7.62 cm x 16.51 cm x 8.89 cm
ID Number
collector/donor number
accession number
catalog number
See more items in
Work and Industry: Electricity
Telegraph Relays & Repeaters
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
from Oberlin College, Dept. of Physics, thru David L. Anderson
Additional Media

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