Transistor radio (Inventions)

The invention: Miniature portable radio that used transistors and created a new mass market for electronic products.

The people behind the invention:

John Bardeen (1908-1991), an American physicist Walter H. Brattain (1902-1987), an American physicist William Shockley (1910-1989), an American physicist Akio Morita (1921-1999), a Japanese physicist and engineer Masaru Ibuka (1907-1997), a Japanese electrical engineer and industrialist

A Replacement for Vacuum Tubes

The invention of the first transistor by William Shockley, John Bardeen, and Walter H. Brattain of Bell Labs in 1947 was a scientific event of great importance. Its commercial importance at the time, however, was negligible. The commercial potential of the transistor lay in the possibility of using semiconductor materials to carry out the functions performed by vacuum tubes, the fragile and expensive tubes that were the electronic hearts of radios, sound amplifiers, and telephone systems. Transistors were smaller, more rugged, and less power-hungry than vacuum tubes. They did not suffer from overheating. They offered an alternative to the unreliability and short life of vacuum tubes.
Bell Labs had begun the semiconductor research project in an effort to find a better means of electronic amplification. This was needed to increase the strength of telephone signals over long distances. Therefore, the first commercial use of the transistor was sought in speech amplification, and the small size of the device made it a perfect component for hearing aids. Engineers from the Raytheon Company, the leading manufacturer of hearing aids, were invited to Bell Labs to view the new transistor and to help assess the commercial potential of the technology. The first transistorized consumer product, the hearing aid, was soon on the market. The early models built by Raytheon used three junction-type transistors and cost more than two hundred dollars. They were small enough to go directly into the ear or to be incorporated into eyeglasses.
The commercial application of semiconductors was aimed largely at replacing the control and amplification functions carried out by vacuum tubes. The perfect vehicle for this substitution was the radio set. Vacuum tubes were the most expensive part of a radio set and the most prone to break down. The early junction transistors operated best at low frequencies, and subsequently more research was needed to produce a commercial high-frequency transistor. Several of the licensees embarked on this quest, including the Radio Corporation of America (RCA), Texas Instruments, and the Tokyo Telecommunications Engineering Company of Japan.

Perfecting the Transistor

The Tokyo Telecommunications Engineering Company of Japan, formed in 1946, had produced a line of instruments and consumer products based on vacuum-tube technology. Its most successful product was a magnetic tape recorder. In 1952, one of the founders of the company, Masaru Ibuka, visited the United States to learn more about the use of tape recorders in schools and found out that Western Electric was preparing to license the transistor patent. With only the slightest understanding of the workings of semiconductors, Tokyo Telecommunications purchased a license in 1954 with the intention of using transistors in a radio set.
The first task facing the Japanese was to increase the frequency response of the transistor to make it suitable for radio use. Then a method of manufacturing transistors cheaply had to be found. At the time, junction transistors were made from slices of germanium crystal. Growing the crystal was not an exact science, nor was the process of “doping” it with impurities to form the different layers of conductivity that made semiconductors useful. The Japanese engineers found that the failure rate for high-frequency transistors was extremely high. The yield of good transistors from one batch ran as low as 5 percent, which made them extremely expensive and put the whole project in doubt. The effort to replace vacuum tubes with components made of semiconductors was motivated by cost rather than performance; if transistors proved to be more expensive, then it was not worth using them.
Engineers from Tokyo Telecommunications again came to the United States to search for information about the production of transistors. In 1954, the first high-frequency transistor was produced in Japan. The success of Texas Instruments in producing the components for the first transistorized radio (introduced by the Regency Company in 1954) spurred the Japanese to greater efforts. Much of their engineering and research work was directed at the manufacture and quality control of transistors. In 1955, they introduced their transistor radio, the TR-55, which carried the brand name “Sony.” The name was chosen because the executives of the company believed that the product would have an international appeal and therefore needed a brand name that could be recognized easily and remembered in many languages. In 1957, the name of the entire company was changed to Sony.


Although Sony’s transistor radios were successful in the marketplace, they were still relatively large and cumbersome. Ibuka saw a consumer market for a miniature radio and gave his engineers the task of designing a radio small enough to fit into a shirt pocket. The realization of this design—”Transistor Six”—was introduced in 1957. It was an immediate success. Sony sold the radios by the millions, and numerous imitations were also marketed under brand names such as “Somy” and “Sonny.” The product became an indispensable part of popular culture of the late 1950′s and 1960′s; its low cost enabled the masses to enjoy radio wherever there were broadcasts.
The pocket-sized radio was the first of a line of electronic consumer products that brought technology into personal contact with the user. Sony was convinced that miniaturization did more than make products more portable; it established a one-on-one relationship between people and machines. Sony produced the first all-transistor television in 1960. Two years later, it began to market a miniature television in the United States. The continual reduction in the size of Sony’s tape recorders reached a climax with the portable tape player introduced in the 1980′s. The Sony Walkman was a marketing triumph and a further reminder that Japanese companies led the way in the design and marketing of electronic products.

John Bardeen

The transistor reduced the size of electronic circuits and at the same time the amount of energy lost from them as heat. Super conduction gave rise to electronic circuits with practically no loss of energy at all. John Bardeen helped unlock the secrets of both.
Bardeen was born in 1908 in Madison, Wisconsin, where his mother was an artist and his father was a professor of anatomy at the University of Wisconsin. Bardeen attended the university, earning a bachelor’s degree in electrical engineering in 1928 and a master’s degree in geophysics in 1929. After working as a geophysicist, he entered Princeton University, studying with Eugene Wigner, the leading authority on solid-state physics, and received a doctorate in mathematics and physics in 1936.
Bardeen taught at Harvard University and the University of Minnesota until World War II, when he moved to the Naval Ordnance Laboratory. Finding academic salaries too low to support his family after the war, he accepted a position at Bell Telephone Laboratories. There, with Walter Brattain, he turned William Shockley’s theory of semiconductors into a practical device—the transfer resistor, or transistor.
He returned to academia as a professor at the University of Illinois and began to investigate a long-standing mystery in physics, superconductivity, with a postdoctoral associate, Leon Cooper, and a graduate student, J. Robert Schrieffer. In 1956 Cooper made a key discovery—superconducting electrons travel in pairs. And while Bardeen was in Stockholm, Sweden, collecting a share of the 1956 Nobel Prize in Physics for his work on transistors, Schrieffer worked out a mathematical analysis of the phenomenon. The theory that the three men published since became known as BCS theory from the first letters of their last names, and as well as explain superconductors, it pointed toward a great deal of technology and additional basic research.
The team won the 1972 Nobel Prize in Physics for BCS theory, making Bardeen the only person to ever win two Nobel Prizes for physics. He retired in 1975 and died sixteen years later.
See also Compact disc; FM radio; Radio; Radio crystal sets; Television; Transistor; Walkman cassette player.

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