Triode Triode A triode is an electronic amplifying vacuum tube (or "thermionic valve" in British English) consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode). Developed from Lee De Forest's 1906 Audion, a partial vacuum tube that added a grid electrode to the thermionic diode (Fleming valve), the triode was the first practical electronic amplifier and the ancestor of other types of vacuum tubes such as the tetrode and pentode. Its invention founded the electronics age, making possible amplified radio technology and long-distance telephony. Triodes were widely used in consumer
Bjork–Shiley valve Bjork–Shiley valve The Björk–Shiley valve is a mechanical prosthetic heart valve. The valve was co-invented by American engineer Donald Shiley and Swedish heart surgeon Viking Björk. Beginning in 1971, it has been used to replace aortic valves and mitral valves. It was the first successful tilting-disc valve. It was manufactured first by Shiley Laboratories, then later by Pfizer after that company purchased Shiley. One model of the Bjork–Shiley valve became the subject of a famous lawsuit and recall after it was shown to malfunction. The Björk–Shiley valve consists of a single carbon-coated disc in a metal housing. The disc is