Selection of valves, 1889-1906.
3 4 c m
40cm
actual image size: 32cm x 26cm

Selection of valves, 1889-1906.

© Science Museum / Science & Society Picture Library

Description

Six valves, including the original thermionic valve of 1889 (back right), made by Sir John Ambrose Fleming (1849-1945) for experiments on an effect seen in early electric lamps. The source of current is a heated negative electrode, the cathode. Current flows through the vacuum to the positive electrode, the anode. In 1899 Fleming became a technical adviser to the Marconi Company, helping design the Poldhu transmitter in Cornwall, used in Guglielmo Marconi's (1874-1937) 1901 transatlantic transmisions. Fleming later developed these valves as sensitive detectors of radio signals. Two of the other valves are: the audion valve of 1906 invented by Lee De Forest (front second from left); a large transmitting triode (back left).
 

Image Ref.

10325835
 

buy a print

Select size
 
Select finish
 
How many prints?
 
£20.00
 

buy a framed print

buy a canvas

buy a framed canvas