Transistor radio
From Tardis Wiki, the free Doctor Who reference
A transistor radio was a device which used a transistor to pick up and play radio signals.
During the Thousand Year War on Skaro, the Fourth Doctor observed that the discovery of a soldier with a uniform partly made of animal skins with a combat jacket made of "modern synthetic fibre" was like finding the remains of a Stone Age man with a transistor radio. (TV: Genesis of the Daleks)
Susan Foreman possessed a transistor radio, which she used to play music. (TV: An Unearthly Child, PROSE: Doctor Who and an Unearthly Child, AUDIO: Hunters of Earth)
Trenix had an encrypted microparticle multibank communicator which he disguised as a transistor radio. Whilst Ann Kelso was fooled, the Fourth Doctor was not. (AUDIO: The Sinestran Kill)
