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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.
The idea of a mobile phone had been around since the 1920's when police radios were in use. Finally, in 1973 Dr. Martin Cooper of Motorola created a cell phone that was usable. It was sold to government projects/offices and in 1984 the first cell was sold to the general public.