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
Gary Birch (electrical engineer) Gary Birch (electrical engineer) Dr. Gary Birch, is a Canadian Paralympian, an expert in Brain-Computer Interface (BCI) technology and Executive Director of the Neil Squire Society. In 1975, Dr. Birch was involved in an automobile accident which resulted in injuries to the C6 and C7 area of his spine making him a low-level quadriplegic. He was one of the original players of Murderball (wheelchair rugby), and won several medals in the 1980 Summer Paralympics in the Netherlands. In 2008, he was appointed an Officer of the Order of Canada. He continues to champion accessibility through his Research and Development work