On November 16, 2004 the age of electronics celebrated its 100th birthday. One century earlier, British engineer John Ambrose Fleming patented the first electronic gadget: a thermionic diode, or vacuum tube, that converted an alternating current into a direct current. The device was inspired by Thomas Edison’s discovery in the 1880s of the Edison Effect, which causes current to flow between two heated electrodes in an evacuated tube. Building on this work, Fleming converted a lightbulb into a simple on-off switch, a fundamental component of an electric circuit. His creation remained the basis for nearly every electrical appliance until the invention of the transistor in the late 1940s.
Not surprisingly, the Web is full of sites about Fleming and the history of electronics.
The Institute of Electrical and Electronics Engineers (IEEE) offers pages on Fleming’s history (www.ieee-virtual-museum.org/collection/tech.php?taid=&id=2345819&lid=1) and on the development of electron tubes (www.ieee.org/organizations/history_center/fleming.html).
More about Fleming and other greats in the history of radio and electronics can be found at www.radio-electronics.com (click on the Radio History link in the left column).
The electrical engineering department at the University of Maryland offers a useful “thumbnail history of electronics” (www.ee.umd.edu/~taylor/Electrons.htm).
Sites at About.com describe the history of vacuum tubes (inventors.about.com/library/inventors/blvacuumtubes.htm) and how they work (stereos.about.com/cs/gtamplifiers/a/tube_amps.htm).