First working transistor, 1947.
© Science Museum / Science & Society Picture Library
Replica of the first working transistor invented in 1947 by John Bardeen, Walter Brattain and William Shockley at Bell Laboratories in the United States. They discovered that by placing two contacts close together on the surface of a crystal of germanium, through which an electric current was flowing, a device which acted as an amplifier was produced. It resembles the 'cat's whisker' detector of earlier radio sets. Transistors are semiconductors which operate as controlling devices in electric circuits. They superseded thermionic valves in fulfilling this purpose, as they operate at a lower voltage, are more compact and robust, and cheaper to make. Their increased miniaturisation has enabled faster procesing speeds in computers to be attained.