Thermionic valve, one of three original examples, by Sir John Ambrose Fleming, London, England, 1904. This valve uses a lamp with a flat rectangular aluminium filament, by Edison & Swan United Electric Company, London, England, 1889.
Original thermionic diode valve invented by Sir John Ambrose Fleming, made by the Edison & Swan United Electric Light Company, London, England, 1889.
This is one of the original valves used by Sir John Ambrose Fleming in his research during 1889 into the 'Edison Effect' - where an extra electrode connected to the positive end of the filament inside a carbon filament light bulb would create a small but measurable charge. After being stored in a cupboard for several years, the valves were once again put to use in 1904 during some experiments by Fleming, resulting in the invention of the two-electrode valve. A few years later American engineer Lee de Forest improved on Fleming’s valve to invent the audion, or triode, which could amplify as well as detect signals. A long and painful legal battle over patent rights for the thermionic valve followed between Fleming and de Forest.
- Electronic Components
- Object Number:
- thermionic emission
- Sir John Ambrose Fleming
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
Download manifest IIIF
Our records are constantly being enhanced and improved, but please note that we cannot guarantee the accuracy of any information shown on this website.