Electron tube types of DC motor controls began to be developed in the 1920s but electronic controls didn’t seriously begin to displace the Ward Leonard system until thyristor controlled drives were developed in the late 1960s.
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Nixie tube, a gas-filled electron tube once in use as an alphanumeric display
He entered Tsinghua University in 1960, majoring in electron tube engineering at the Department of Radio Electronics, where he graduated in 1967.