Double-current telegraph key, 1830-1900

Double-current telegraph key Double-current telegraph key Double-current telegraph key Double-current telegraph key

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Creative Commons LicenseThis image is released under a CC BY-SA 4.0 Licence

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License this image for commercial use at Science and Society Picture Library

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Creative Commons LicenseThis image is released under a CC BY-SA 4.0 Licence

Buy this image as a print 

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License this image for commercial use at Science and Society Picture Library

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Creative Commons LicenseThis image is released under a CC BY-SA 4.0 Licence

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Double-current telegraph key
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Double-current telegraph key
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Double-current telegraph key
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Double-current telegraph key
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Double-current telegraph key, probably made and used by the Post Office, British, 1830-1900.

With a single-current telegraph key the position of the relay is restored to the normal position when current ceases by a magnetic bias or by a spring in tension. In other words, signal currents only flow in the line when the key is depressed. In the double-current system a current in the reverse direction is used to restore the relay to the spacing side. This example is similar to those used with the Bright's bell, or acoustic telegraph.

Details

Category:
Telecommunications
Object Number:
1953-111
Materials:
wood (unidentified), metal (unknown), copper (alloy) and mother-of-pearl
Measurements:
overall: 60 mm x 130 mm x 230 mm, .86 kg
type:
telegraph
credit:
Donated by the Institution of Electrical Engineers