One of Fleming's first thermionic diode valves, 1889

Made:
1889 in London
inventor:
John Ambrose Fleming
One of Fleming's first thermionic diode valves, 1889 (thermionic valve) One of Fleming's first thermionic diode valves, 1889 (thermionic valve) One of Fleming's first thermionic diode valves, 1889 (thermionic valve) Original thermionic diode valve invented by Sir John Ambrose Original thermionic diode valve invented by Sir John Ambrose Original thermionic diode valve invented by Sir John Ambrose

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Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Original thermionic diode valve invented by Sir John Ambrose
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Original thermionic diode valve invented by Sir John Ambrose
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Original thermionic diode valve invented by Sir John Ambrose
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Thermionic valve, one of three original examples, by Sir John Ambrose Fleming, London, England, 1904. This valve uses a lamp with a flat concertina wire 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.

Details

Category:
Electronic Components
Object Number:
1925-814/3
Materials:
glass, metal (unknown), wood (unidentified) and textile
Measurements:
overall: 225 mm x 70 mm diameter
type:
thermionic valve
credit:
Sir John Ambrose Fleming