FREQUENCIES Home
Wireless (pre-1920) Radios
Marconi Wireless (pre-1920) Sets
Tubes & Valves
Crystal Set Radios
Antique Radios (1920s)
Antique Radios (1930-1960s)
Antique Radio Advertising
Radio Speakers & Microphones
Articles on Antique Radio I Have Written
Wanted Radios
Tubes for sale
Tube Amplifiers
Defeating Depression book by Howard Stone
Interview of Howard Stone on Tube Talk Classic Radio Show
Early Books and Literature on Radio, Tubes, & Electricity
Contact
Me
|
| Fleming Valve, American Marconi company | Pictured are three Fleming valves made by the American Marconi company. The Fleming Valve was the first commercial application of the Edison Effect (The flow of electrons through space by a heated element) used as a vacuum tube rectifier and detector. J.A. Fleming in developed the tube in 1904. The Fleming Valve is by most accounts the grandfather of the modern vacuum tube. It functions as a rectifier when a positive charge is applied. Electrons emitted from the filament pass through the vacuum of the tube and are accumulated at the metal plate (or anode). It is hard to estimate how many of these Fleming valves are still in existence. One knowledgable authority suggested that there were about 60 in the US, about 30 in the U.K. and about 20 or so elsewhere. Pictured are three different Fleming Valves. You see two different shapes of glass enclosures. The valve on the left has one plate and the other two have two plates. I assume that the single plate is an earlier version of the valve. The valve on the right has an intact carbon filament. |
|