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Most vacuum tubes have a limited lifetime, due mainly to the filament burning out or the cathode coating becoming depleted, gradually reducing performance, with other failure modes, so they are made as replaceable units; the electrode leads connect to pins on the tube's base which plug into a tube socket making tubes, a frequent cause of ...
A glowing plate in a vacuum tube circuit indicates that the tube is drawing excessive current. This causes the anode ("plate") to overheat and radiate a visible red or orange glow. In consumer electronics, this is universally indicative that the tube is experiencing an overload condition, though the reasons for the overload may vary.
Research has also identified a particular failure mode for tin whiskers in vacuum (such as in space), where in high-power components a short-circuiting tin whisker is ionized into a plasma that is capable of conducting hundreds of amperes of current, massively increasing the damaging effect of the short circuit. [12]
In this type, the filament is not the cathode but rather heats a separate cathode consisting of a sheet metal cylinder surrounding the filament, and the cylinder emits electrons. Indirectly heated cathodes are used in most low power vacuum tubes. For example, in most vacuum tubes the cathode is a nickel tube, coated with metal oxides.
Schematic symbol used in circuit diagrams for a vacuum tube, showing control grid. The control grid is an electrode used in amplifying thermionic valves (vacuum tubes) such as the triode, tetrode and pentode, used to control the flow of electrons from the cathode to the anode (plate) electrode. The control grid usually consists of a cylindrical ...
For the catastrophic failure of other pressure vessels used to contain gas, liquids, or reactants under pressure, the term explosion is more commonly used, or other specialised terms such as BLEVE may apply to particular situations. Decompression can occur due to structural failure of the pressure vessel, or failure of the compression system ...
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The suppressor grid and pentode tube were invented in 1926 by Gilles Holst and Bernard D. H. Tellegen at Phillips Electronics. [1] [2] In a vacuum tube, electrons emitted by the heated cathode are attracted to the positively-charged plate and pass through the grids to the plate. When they strike the plate they knock other electrons out of the ...