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.
Les Hoffman
The invention of the transistor in 1948 must have had an effect on Leslie Hoffman. In the early 1950s, he took a major interest in solar cells, also called photovoltaic cells. When Bell Labs introduced the solar cell to the world in 1951 it was only a curiosity. It had a very poor light-to-electricity conversion efficiency of 2 percent, and was very fragile and expensive to fabricate. Several manufacturers, including Hoffman, managed to improve the efficiency to 4.5 percent by 1954, but photovoltaic cells were still impractical.
Hoffman made great strides in making the solar cell a practical and useful source of renewable energy. From 1957 to 1960, he improved its efficiency from 4.5 to 14 percent and lowered the production cost to make it a marketable item. One of Hoffman's great achievements was the first satellite to be powered by solar cells, the Vanguard 1, launched in 1958. The solar arrays or panels are Hoffman photovoltaic cells. In 1959 H. Leslie Hoffman received the David Packard Medal of Achievement for innovation. In 1959 he was one of the board of directors for the Electronic Industries Association (EIA).