This image is released under a CC BY-NC-SA 4.0 Licence
Buy this image as a print
License this image for commercial use at Science and Society Picture Library
SMG00237639 Science Museum Group © The Board of Trustees of the Science Museum
Wade Bequest collection of valves: experimental directly-heated triode radio valve by Marconi-Osram with pip top and B4-3 base with two hinged caps at each end of the anode.