Amplifier by their physical placement in the signal chain; a preamplifier may precede other signal processing stages, for example. The first practical electrical device which could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Today most amplifiers use transistors. The first practical device that could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Vacuum tubes were used in almost all amplifiers until the 1960s–1970s when the transistor, invented in 1947, replaced them. Today, most amplifiers
John P. Costas (engineer) properties for the problem. Costas was made a fellow of the Institute of Electrical and Electronics Engineers (IEEE) in 1965 for "contributions to communications theory and techniques." Among Costas' most notable publications are the following, John P. Costas (engineer) John Peter Costas (1923 in Wabash, Indiana – 2008) was an American electrical engineer. Costas invented, among other things, the Costas loop and Costas arrays. Costas studied at Purdue University as an undergraduate. During World War II, he was involved in radar engineering, serving in the U.S. Navy as a radar officer. He was a graduate student at Massachusetts Institute of