History of hearing aids
The development of transistors in 1948 by Bell Laboratories led to major improvements to the hearing aid. The transistor was invented by John Bardeen, Walter Brattain, and William Shockley. Transistors were created to replace vacuum tubes; they were small, required less battery power and had less distortion and heat than their predecessor. These vacuum tubes were typically hot and fragile, so the transistor was the ideal replacement.The 1952 Sonotone 1010 used a transistor stage along with vacuum tubes, to extend battery life. The size of these transistors led to developments in miniature, carbon microphones. These microphones could be mounted on various items, even eyeglasses. In 1951, Raytheon manufactured the transistor and was one of the first companies to mass-produce transistors to throughout America. Raytheon realized that their hearing aid only lasted short-term and began to sell the vacuum-tube hearing aids again along with transistor hearing aids.
Surface-barrier transistor
In 1956-57, Remington Rand St. Paul Univac-division of Sperry Rand Corporation, had designed and built a transistorized "test" computer for the United States Air Force, which was called "TRANSTEC". It was designed by Univac's St. Paul engineer Seymour Cray, and used the Philco's high-frequency surface-barrier transistors in its computer's circuitry design. This was Univac's first computer designed with transistors and was used to test transistor logic circuits and also its speed and reliability, compared to magnetic amplifier (MAGSTEC) and vacuum tube circuit computers. After Univac had demonstrated the TRANSTEC computer to the United States Air Force, it was awarded a contract to build a transistorized ground guidance (Athena) ICBM defense computer.