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
Slide valve be side-by-side. The balanced slide valve was invented by the Scottish engineer Alexander Allan. It was not much used in the UK but, at one time, had great popularity in the United States. It gave some of the advantages of a piston valve to a slide valve by relieving the pressure on the back of the valve, thus reducing friction and wear. Slide valve The slide valve is a rectilinear valve used to control the admission of steam into, and emission of exhaust from, the cylinder of a steam engine. In the 19th century, most steam locomotives used slide valves