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
Scott Hudson (electrical engineer) Scott Hudson (electrical engineer) Raymond Scott Hudson (born 1959) is a professor of electrical engineering and computer science at Washington State University. Hudson was educated at Caltech, where he received his bachelor's degree in engineering and applied science in 1985, his master's degree in electrical engineering in 1986, and his PhD in electrical engineering in 1990. His research interests include radar imaging, optical signal processing, and radar astronomy. From August 19 to 22 of 1989, Hudson and Steven Ostro observed 4769 Castalia from the Arecibo Observatory, producing the first direct image of an asteroid. The main-belt asteroid 5723 Hudson, discovered