Transistor radio
A transistor radio is a small portable radio receiver that uses transistor-based circuitry. Following their development in 1954, made possible by the invention of the transistor in 1947, they became the most popular electronic communication device in history, with billions manufactured during the 1960s and 1970s. Their pocket size sparked a change in popular music listening habits, allowing people to listen to music anywhere they went. Beginning in the 1980s, however, cheap AM transistor radios were superseded by devices with higher audio quality such as portable CD players, personal audio players, boomboxes, and (eventually) smartphones, some of which contain radios themselves.
History of the transistor
The TR-55 was quite similar to the Regency TR-1 in many ways, being powered by the same sort of 22.5-volt battery, and was not much more practical. Note: according to the schematic, the TR-55 used a 6 volt supply. Very few were distributed outside Japan. It was not until 1957 that Sony produced their ground-breaking "TR-63" shirt pocket radio, a much more advanced design that ran on a standard 9-volt battery and could compete favorably with vacuum tube portables. The TR-63 was also the first transistor radio to use all miniature components. (The term "pocket" was a matter of some interpretation, as Sony allegedly had special shirts made with oversized pockets for their salesmen.)