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A classic Emerson transistor radio, circa 1958. A transistor radio is a small portable radio receiver that uses transistor-based circuitry.Previous portable radios used vacuum tubes, which were bulky, fragile, had a limited lifetime, consumed excessive power and required large heavy batteries.
Until the mid- to late-1920s, all radios except crystal sets were powered by vacuum tube batteries which were expensive, needed frequent charging, and leaked battery acid, reducing the wife approval factor in the home. A very successful August 1925 Philco consumer product, called the "Socket Power Battery Eliminator", was a rectifier unit which ...
A 22.5 volt battery provides power, since the only way to get adequate radio frequency performance out of early transistors was to run them close to their collector-to-emitter breakdown voltage. The current drain from this battery is only 4 mA, [ 7 ] allowing 20 to 30 hours of operation, in comparison to only several hours for the portable ...
Sarkis Acopian invented the first solar-powered radio in 1957. An experimental model, developed by General Electric, weighed just 10 ounces and was capable of working without light and recharging. It contained seven solar cells, four transistors and a small battery.
It was designed by G.D. Reynolds of Murphy Radio. Both AC and battery-operated versions were made. [7] [8] [9] Walkman – The original Walkman, released in 1979, was a portable cassette player. The Walkman brand was later extended to serve most of Sony's portable audio devices as well as related media devices, including radio receivers.
In present Freeplay radios and other products, clockwork mechanisms storing energy in a mainspring have now been replaced by small batteries charged by cheaper hand-crank generators. [9] Freeplay Energy produces a variety of consumer devices in addition to radios, including flashlights, lanterns, mobile phone chargers, and foot-powered generators.
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