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This is a list of vacuum tubes or thermionic valves, and low-pressure gas-filled tubes, or discharge tubes. Before the advent of semiconductor devices, thousands of tube types were used in consumer electronics.
The earliest vacuum tubes evolved from incandescent light bulbs, containing a filament sealed in an evacuated glass envelope. When hot, the filament in a vacuum tube (a cathode) releases electrons into the vacuum, a process called thermionic emission. This can produce a controllable unidirectional current though the vacuum known as the Edison ...
image - Picture of the vacuum tube; caption - Caption for the picture; classification - Mandatory Field exampled include: cold cathode regulator, diode dual diode, triode, dissimilar triode, tetrode, beam tetrode, pentode etc. service - Common application of the tube examples include, Class A amplifier, AF modulator, RF amplifier
It is easily machined and has good corrosion resistance. It is unsuitable for bakeable vacuum envelopes due to its tendency to oxidize and create scales. Copper rings are used in demountable seals. Normal copper is unsuitable for high vacuum as it is difficult to outgas completely. Copper is insensitive to hydrogen and impermeable to hydrogen ...
Most post-war European thermionic valve (vacuum tube) manufacturers have used the Mullard–Philips tube designation naming scheme. Special quality variants may have the letter "S" appended, or the device description letters may be swapped with the numerals (e.g. an E82CC is a special quality version of an ECC82)
In Europe, the principal method of numbering vacuum tubes ("thermionic valves") was the nomenclature used by the Philips company and its subsidiaries Mullard in the UK, Valvo (de, it) in Germany, Radiotechnique (Miniwatt-Dario brand) in France, and Amperex in the United States, from 1934 on.
The Radio Electronics Television Manufacturers' Association was formed in 1953, as a result of mergers with other trade standards organisations, such as the RMA.It was principally responsible for the standardised nomenclature for American vacuum tubes - however the standard itself had already been in use for a long time before 1953; for example, the 6L6 was introduced in July 1936.
The second character was a letter broadly identifying the class of tube: A-- Single element (ballast, barretter) B-- Two-element device such as: Diode; Transmit/receive tube (TR cell), cold-cathode water vapor discharge tube for use in radar systems, shorts the receiver input to protect it while the transmitter operates