A key development in radio’s adaptation to television occurred with the invention of the transistor by Bell Laboratories in 1947. Transistors were small electrical devices that, like vacuum tubes, could receive and amplify radio signals. However, they used less power and produced less heat than vacuum tubes, and they were more durable and less expensive. Best of all, they were tiny. Transistors, which also revolutionized hearing aids, constituted the first step in replacing bulky and delicate tubes, leading eventually to today’s integrated circuits.

Texas Instruments marketed the first transistor radio in 1953 for about $40. Using even smaller transistors, Sony introduced the pocket radio in 1957. But it wasn’t until the 1960s that transistor radios became cheaper than conventional tube and battery radios. For a while, the term transistor became a synonym for a small, portable radio.

The development of transistors let radio go where television could not—to the beach, to the office, into bedrooms and bathrooms, and into nearly all new cars. (Before the transistor, car radios were a luxury item.) By the 1960s, most radio listening took place outside the home.