Edison Swan thermionic triode valve
1932
Marconi Wireless Telegraph thermionic triode valve
1918
Triotron thermionic triode valve
1935
Metropolitan-Vickers Cosmos thermionic triode valve
1925
Ediswan thermionic triode valve
1928
Marconi Osram triode valve
circa 1920
Marconi thermionic triode valve
1927
Marconi Osram thermionic triode valve
1925
Marconi thermionic triode valve
1923
Cleartron thermionic triode valve
1927
Neutron thermionic triode valve
1930
Thermionic triode valve
circa 1920s-1930s
Mullard Triode Valve MZ05-60
Mullard thermionic triode valve
1928
Marconi Osram thermionic triode valve
1923
Marconi thermionic triode valve
1923
Marconi Osram thermionic triode valve
1935
Wade Bequest: ORA triode radio valve
Metropolitan-Vickers Cosmos thermionic triode valve
1923
Marconi Osram thermionic triode valve
1927
British Thomson-Houston thermionic triode valve
1924
Thermionic triode valve
Edison Swan thermionic triode valve
1930
Metropolitan-Vickers Cosmos thermionic triode valve
1925
Cossor triode valve
circa 1930
Moorhead thermionic triode valve
1922
Wade Bequest: DER triode radio valve
Marconi Osram thermionic triode valve
1925
Metropolitan-Vickers thermionic triode valve
1925
Marconi Osram thermionic triode valve
1925
Marconi-Osram LS3 triode, BBC-marked
Mullard ORA triode
Thermionic triode valve
Thermionic triode valve
Wade Bequest: DER triode radio valve
Amrex thermionic triode valve
circa 1923
Marconi Osram thermionic triode valve
1925
Fellows thermionic triode valve
1923
Marconi thermionic triode valve
1940
Marconi thermionic triode valve
1923
Marconi Osram thermionic triode valve
1923
Marconi triode valve
1930
Thermionic triode valve
Triode valve
Triode valve
Triode valve
1931
Duval triode valve
1928
Wade Bequest: DE6b triode radio valve with green tint
Wade Bequest: DE6 triode radio valve with blue tint
