UNITED KINGDOM - JULY 13: In 1948, William Shockley (1910-1989) invented the transistor, and in the 1950s, transistors began to replace thermionic valves in radio receivers, allowing much smaller, more affordable portable radios to be produced. Manufactured by the Dynatron company, the 'Nomad', is an early example of a portable transistor radio. Its main components are a variable capacitor, a transistor battery, 7 pnp transistors and 2 diodes, all of which are tightly packed inside the leatherette case. The variable capacitor makes the radio pick up signals of different frequency, which in turn allows the listener to hear a variety of stations. (Photo by SSPL/Getty Images)
