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 Beginning in the 1980s, however, cheap AM transistor radios were superseded by devices with higher audio quality such as portable CD players, personal audio players, boomboxes, and (eventually) smartphones, some of which contain radios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.
Invention of radio
By the summer of 1906, a machine producing 50 kilohertz was installed at the Brant Rock station, and in the fall of 1906, what was called an electric alternating dynamo was working regularly at 75 kilohertz, with an output of 0.5 kW. Fessenden used this for wireless telephoning to Plymouth, Massachusetts, a distance of approximately . In the following year machines were constructed having a frequency of 96 kilohertz and outputs of 1 kW and 2 kW. Fessenden believed that the damped wave-coherer system was essentially and fundamentally incapable of development into a practical system. He would employ a two-phase high frequency "alternator method" and the continuous production of waves with changing constants of sending circuit. Fessenden would also use duplex and multiplex commutator methods. On December 11, 1906, operation of the wireless transmission in conjunction with the wire lines took place. In July 1907 the range was considerably extended and speech was successfully transmitted between Brant Rock and Jamaica, on Long Island, a distance of nearly , in daylight and mostly over land, the mast at Jamaica being approximately high.