Morse key with send-receive switch, made by the General Post Office, British, 1900-1920.
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. The 'send-receive' switch is necessary to disconnect the key from line while signals are being received, otherwise a spacing current flows along the line, preventing signals from being sent from the other end.
- Science Museum, Information Age Gallery: Cable
- Object Number:
- brass (copper, glass, plastic (unidentified), steel (metal), wood (unidentified), zinc alloy)
- component - object
- Donated by the Institution of Electrical Engineers
- Permanent collection
Cite this page
We encourage the use and reuse of our collection data.
Data in the title, made, maker and details fields are released under Creative Commons Zero
Descriptions and all other text content are licensed under a Creative Commons Attribution 4.0 licence
Download catalogue entry as json
Our records are constantly being enhanced and improved, but please note that we cannot guarantee the accuracy of any information shown on this website.