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
Vienna valve trombone Vienna valve trombone Vienna valve trombones use Vienna Valves which were one of the earliest valve systems used in wind instruments. These valves were first publicly reported in 1815 and valved trombones were first introduced in the late 1830s. The Vienna valve was invented in Leipzig in 1821 by Sattler, predating the Perinet valve and rotary valve used in France and Germany (and in all French horns). The Vienna Valves (or Double Valves) have two short parallel pistons connected at the bottom by a bar that is moved by a long rod or linkage connected to the spring-loaded finger plate.