Editing Triode (section)

{{Short description|Single-grid amplifying vacuum tube having three active electrodes}}
{{About|the electronic vacuum tube|the Eastern Orthodox structure of hymns|Triodion}}
{{Infobox electronic component
| name              = Triode
| image             = Triody var.jpg
| caption           = Examples of low power triodes from 1918 ''(left)'' to miniature tubes of the 1960s ''(right)''
| type              = Active
| working_principle = [[Thermionic emission]]
| inventor          = [[Lee de Forest]]
| invention_Year    = 1908
| pins              = [[Plate electrode|Plate]], [[Control grid|grid]], and [[Hot cathode|cathode]]
| symbol            = [[File:Triode schematic with filament and cathode.svg|80px]]
}}

{{multiple image
| align = right
| direction = horizontal
| header   =
| image1   = Dubulttriode darbiibaa.jpg
| caption1 = [[ECC83]], a dual triode used in 1960-era audio equipment, showing the orange glow of the hot cathode.
| width1   = 132
| image2   = 3CX1500A7.jpg
| caption2 = 3CX1500A7, a modern 1.5&nbsp;kW power triode used in radio trans&shy;mitters. The cylindrical structure is a heat sink atta&shy;ched to the plate, through which air is blown during operation.
| width2   = 181
}}

A '''triode''' is an electronic [[amplifier|amplifying]] [[vacuum tube]] (or ''thermionic valve'' in [[British English]]) consisting of three [[electrode]]s inside an evacuated glass envelope: a heated [[Electrical filament|filament]] or [[cathode]], a [[control grid|grid]], and a [[Plate electrode|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 helped make amplified [[radio technology]] and long-distance [[telephony]] possible. <ref name="Nebeker" /> Triodes were widely used in [[consumer electronics]] devices such as radios and televisions until the 1970s, when [[transistor]]s replaced them. Today, their main remaining use is in high-power [[Radio frequency|RF]] amplifiers in [[Transmitter|radio transmitters]] and industrial RF heating devices. In recent years there has been a resurgence in demand for low power triodes due to renewed interest in tube-type audio systems by audiophiles who prefer{{vague|date=October 2021}} the sound of tube-based electronics.{{Citation needed|date=December 2021}}