
One of Fleming's first thermionic diode valves, 1889
1889
1889
1889
1896
1897-1898
1890-1900
1830 (original); 1967 (model)
1839 (original); circa 1988 (replica)
1801-1840 (original); 1901 (model)
1775-1799 (original); 1900-1907 (model)
1897
1888
1901
circa 1900
1900
1899
1890
1898-1900
1901
1886-1887
1900
1895
1896
circa 1897
1955; 1830
1890 - 1900
before 1889
before 1889
1895-1899
1889
1898-1899
1894
1895-1900
1900
1899
1890-1896
1890-1894
1890-1894
1890-1894
1898
1890-1900
1891-1900
1890-1899
circa 1900
1901
1898
1901
1896
About 1890
1890
1896