Triode were invented, Philipp Lenard used the principle of grid control while conducting photoelectric experiments in 1902. The first vacuum tube used in radio was the thermionic diode or Fleming valve, invented by John Ambrose Fleming in 1904 as a detector for radio receivers. It was an evacuated glass bulb containing two electrodes, a heated filament and a plate (anode). Triodes came about in 1906 when American engineer Lee De Forest and Austrian physicist Robert von Lieben independently patented tubes that added a third electrode, a grid, between the filament and plate to control current. Von Lieben's partially-evacuated three-element tube, patented
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