Bunnell duplex 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 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.

Date Made: ca 1920

Maker: J. H. Bunnell & Co.J. H. Bunnell

Location: Currently not on view

See more items in: Work and Industry: Electricity, Communications, Telegraph Relays & Repeaters


Exhibition Location:

Credit Line: from Western Union Corporation

Data Source: National Museum of American History

Id Number: EM.331390Catalog Number: 331390Accession Number: 294351Collector/Donor Number: 100-027

Object Name: telegraph relayduplex telegraph relay

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

Guid: http://n2t.net/ark:/65665/ng49ca746ac-c500-704b-e053-15f76fa0b4fa

Record Id: nmah_1365334

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.