Vacuum tube - Knowledge

1809: 1854:(who conceived Colossus) wrote that most radio equipment was "carted round, dumped around, switched on and off and generally mishandled. But I'd introduced valves into telephone equipment in large numbers before the war and I knew that if you never moved them and never switched them on and off they would go on forever". Colossus was "that reliable, extremely reliable". On its first day at BP a problem with a known answer was set. To the amazement of BP (Station X), after running for four hours with each run taking half an hour the answer was the same every time (the Robinson did not always give the same answer). Colossus I used about 1600 valves, and Colossus II about 2400 valves (some sources say 1500 (Mk I) and 2500 (Mk II); the Robinson used about a hundred valves; some sources say fewer). 1386:. This 1920s device has three triodes in a single glass envelope together with all the fixed capacitors and resistors required to make a complete radio receiver. As the Loewe set had only one tube socket, it was able to substantially undercut the competition, since, in Germany, state tax was levied by the number of sockets. However, reliability was compromised, and production costs for the tube were much greater. In a sense, these were akin to integrated circuits. In the United States, Cleartron briefly produced the "Multivalve" triple triode for use in the Emerson Baby Grand receiver. This Emerson set also has a single tube socket, but because it uses a four-pin base, the additional element connections are made on a "mezzanine" platform at the top of the tube base. 2501:"Special quality" versions of standard tubes were often made, designed for improved performance in some respect, such as a longer life cathode, low noise construction, mechanical ruggedness via ruggedized filaments, low microphony, for applications where the tube will spend much of its time cut off, etc. The only way to know the particular features of a special quality part is by reading the datasheet. Names may reflect the standard name (12AU7==>12AU7A, its equivalent ECC82==>E82CC, etc.), or be absolutely anything (standard and special-quality equivalents of the same tube include 12AU7, ECC82, B329, CV491, E2163, E812CC, M8136, CV4003, 6067, VX7058, 5814A and 12AU7A). 2119:, also extended to transistors, uses a letter, followed by one or more further letters, and a number. The type designator specifies the heater voltage or current (one letter), the functions of all sections of the tube (one letter per section), the socket type (first digit), and the particular tube (remaining digits). For example, the ECC83 (equivalent to the 12AX7) is a 6.3V (E) double triode (CC) with a miniature base (8). In this system special-quality tubes (e.g., for long-life computer use) are indicated by moving the number immediately after the first letter: the E83CC is a special-quality equivalent of the ECC83, the E55L a power pentode with no consumer equivalent. 661:: the voltage applied to the control grid affects the current between the cathode and the plate. When held negative with respect to the cathode, the control grid creates an electric field that repels electrons emitted by the cathode, thus reducing or even stopping the current between cathode and anode. As long as the control grid is negative relative to the cathode, essentially no current flows into it, yet a change of several volts on the control grid is sufficient to make a large difference in the plate current, possibly changing the output by hundreds of volts (depending on the circuit). The solid-state device which operates most like the pentode tube is the 2528: 2471:, may be incorporated in the equipment's heater supply or a ramp-up circuit may be employed to allow the heater or filaments to reach operating temperature more gradually than if powered-up in a step-function. Low-cost radios had tubes with heaters connected in series, with a total voltage equal to that of the line (mains). Some receivers made before World War II had series-string heaters with total voltage less than that of the mains. Some had a resistance wire running the length of the power cord to drop the voltage to the tubes. Others had series resistors made like regular tubes; they were called ballast tubes. 1248: 1244:, eliminating the need for neutralizing circuitry at medium wave broadcast frequencies. The screen grid also largely reduces the influence of the plate voltage on the space charge near the cathode, permitting the tetrode to produce greater voltage gain than the triode in amplifier circuits. While the amplification factors of typical triodes commonly range from below ten to around 100, tetrode amplification factors of 500 are common. Consequently, higher voltage gains from a single tube amplification stage became possible, reducing the number of tubes required. Screen grid tubes were marketed by late 1927. 951: 2311: 1556: 1713:

the cathode circuit to be separated from the heater circuit. The filament, no longer electrically connected to the tube's electrodes, became simply known as a "heater", and could as well be powered by AC without any introduction of hum. In the 1930s, indirectly heated cathode tubes became widespread in equipment using AC power. Directly heated cathode tubes continued to be widely used in battery-powered equipment as their filaments required considerably less power than the heaters required with indirectly heated cathodes.

1661: 2128: 1869: 48: 1762:, "discovered that, so long as valves were switched on and left on, they could operate reliably for very long periods, especially if their 'heaters' were run on a reduced current". In 1934 Flowers built a successful experimental installation using over 3,000 tubes in small independent modules; when a tube failed, it was possible to switch off one module and keep the others going, thereby reducing the risk of another tube failure being caused; this installation was accepted by the 2786: 580:, will attract those electrons if it is at a more positive voltage. The result is a net flow of electrons from the filament to plate. However, electrons cannot flow in the reverse direction because the plate is not heated and does not emit electrons. The filament has a dual function: it emits electrons when heated; and, together with the plate, it creates an electric field due to the potential difference between them. Such a tube with only two electrodes is termed a 298: 1617: 494: 2436: 1917:

cutoff with the heater on accelerates cathode poisoning and the output current of the tube will be greatly reduced when switched into conduction mode. The 7AK7 tubes improved the cathode poisoning problem, but that alone was insufficient to achieve the required reliability. Further measures included switching off the heater voltage when the tubes were not required to conduct for extended periods, turning on and off the heater voltage with a slow ramp to avoid

471: 154: 2611:, comes from helium infiltration. The effect appears as impaired or absent functioning, and as a diffuse glow along the electron stream inside the tube. This effect cannot be rectified (short of re-evacuation and resealing), and is responsible for working examples of such tubes becoming rarer and rarer. Unused ("New Old Stock") tubes can also exhibit inert gas infiltration, so there is no long-term guarantee of these tube types surviving into the future. 933:(or simply "grid") was lowered from the cathode's voltage to somewhat more negative voltages, the amount of current from the filament to the plate would be reduced. The negative electrostatic field created by the grid in the vicinity of the cathode would inhibit the passage of emitted electrons and reduce the current to the plate. With the voltage of the grid less than that of the cathode, no direct current could pass from the cathode to the grid. 142: 2649:

vacuum tubes were more efficient than solid-state circuits at RF power levels above approximately 20 kilowatts, this is no longer the case, especially in medium wave (AM broadcast) service where solid-state transmitters at nearly all power levels have measurably higher efficiency. FM broadcast transmitters with solid-state power amplifiers up to approximately 15 kW also show better overall power efficiency than tube-based power amplifiers.

1973: 3472: 3150: 868: 2729:(being a highly reactive metal) is effective against many atmospheric gases but has no (or very limited) chemical reactivity to inert gases such as helium. One progressive type of failure, especially with physically large envelopes such as those used by camera tubes and cathode-ray tubes, comes from helium infiltration. The exact mechanism is not clear: the metal-to-glass lead-in seals are one possible infiltration site. 780: 2252:

but was only permitted to conduct when the igniter in contact with the mercury had enough current to vaporize the mercury and complete the circuit. Because this was used in resistance welding there were two Ignatrons for the two phases of an AC circuit. Because of the mercury at the bottom of the tube they were extremely difficult to ship. These tubes were eventually replaced by SCRs (Silicon Controlled Rectifiers).

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on the inside of the glass envelope, leaving a silver-colored metallic patch that continues to absorb small amounts of gas that may leak into the tube during its working life. Great care is taken with the valve design to ensure this material is not deposited on any of the working electrodes. If a tube develops a serious leak in the envelope, this deposit turns a white color as it reacts with atmospheric

1774:, with over 17,000 tubes, had a tube failure (which took 15 minutes to locate) on average every two days. The quality of the tubes was a factor, and the diversion of skilled people during the Second World War lowered the general quality of tubes. During the war Colossus was instrumental in breaking German codes. After the war, development continued with tube-based computers including, military computers 3072: 1734: 883: 1325: 1207: 525:, although ceramic and metal envelopes (atop insulating bases) have been used. The electrodes are attached to leads which pass through the envelope via an airtight seal. Most vacuum tubes have a limited lifetime, due to the filament or heater burning out or 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 2037: 5354: 1584: 838:) when the plate was at a positive voltage with respect to the cathode. Electrons could not pass in the reverse direction because the plate was not heated and not capable of thermionic emission of electrons. Fleming filed a patent for these tubes, assigned to the Marconi company, in the UK in November 1904 and this patent was issued in September 1905. Later known as the 2045: 1464: 2592:. Early gettered tubes used phosphorus-based getters, and these tubes are easily identifiable, as the phosphorus leaves a characteristic orange or rainbow deposit on the glass. The use of phosphorus was short-lived and was quickly replaced by the superior barium getters. Unlike the barium getters, the phosphorus did not absorb any further gases once it had fired. 891: 730:, that became well known. Although Edison was aware of the unidirectional property of current flow between the filament and the anode, his interest (and patent) concentrated on the sensitivity of the anode current to the current through the filament (and thus filament temperature). It was years later that 1371:(at a high voltage). Many designs use such a screen grid as an additional anode to provide feedback for the oscillator function, whose current adds to that of the incoming radio frequency signal. The pentagrid converter thus became widely used in AM receivers, including the miniature tube version of the " 2958:

was marketed, but did not last.) However, eventually, Philips of the Netherlands developed the EFP60 tube that had a satisfactory lifetime and was used in at least one product, a laboratory pulse generator. By that time, however, transistors were rapidly improving, making such developments superfluous.

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lower-powered tubes. The result was that heaters that warmed up faster also temporarily had higher resistance, because of their positive temperature coefficient. This disproportionate resistance caused them to temporarily operate with heater voltages well above their ratings, and shortened their life.

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made a high-performance wideband oscilloscope CRT with a channel electron multiplier plate behind the phosphor layer. This plate was a bundled array of a huge number of short individual c.e.m. tubes that accepted a low-current beam and intensified it to provide a display of practical brightness. (The

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included in the circuit. Tubes intended for series-string operation of the heaters across the supply have a specified controlled warm-up time to avoid excess voltage on some heaters as others warm up. Directly heated filament-type cathodes as used in battery-operated tubes or some rectifiers may fail

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A catastrophic failure is one that suddenly makes the vacuum tube unusable. A crack in the glass envelope will allow air into the tube and destroy it. Cracks may result from stress in the glass, bent pins or impacts; tube sockets must allow for thermal expansion, to prevent stress in the glass at the

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external cavity klystron in the visual circuit of its transmitter; this is the highest documented service life for this type of tube. It has been said that transmitters with vacuum tubes are better able to survive lightning strikes than transistor transmitters do. While it was commonly believed that

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The Ignatron tube was used in resistance welding equipment in the early 1970s. The Ignatron had a cathode, anode and an igniter. The tube base was filled with mercury and the tube was used as a very high current switch. A large current potential was placed between the anode and cathode of the tube

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is a double triode (two sets of three electrodes plus heater) with a 12.6V heater (which, as it happens, can also be connected to run from 6.3V). The "AX" designates this tube's characteristics. Similar, but not identical, tubes are the 12AD7, 12AE7...12AT7, 12AU7, 12AV7, 12AW7 (rare), 12AY7, and the

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comprise a number, followed by one or two letters, and a number. The first number is the (rounded) heater voltage; the letters designate a particular tube but say nothing about its structure; and the final number is the total number of electrodes (without distinguishing between, say, a tube with many

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pentode of 1948 (these replaced the 7AD7, which was supposed to be better quality than the standard 6AG7 but proved too unreliable). Computers were the first tube devices to run tubes at cutoff (enough negative grid voltage to make them cease conduction) for quite-extended periods of time. Running in

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electrons to the anode when the anode potential is less than that of the screen grid. Formation of beams also reduces screen grid current. In some cylindrically symmetrical beam power tubes, the cathode is formed of narrow strips of emitting material that are aligned with the apertures of the control

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designed for radio frequency use. The tube plugs in to a socket that creates an air-tight seal around the outer periphery. A blower and duct work in the chassis force air through the tube's fins to carry away heat. This type of tube is sometimes referred to as a "doorknob" tube, owing to its shape

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brought the Audion for demonstration to AT&T's engineering department. Dr. Harold D. Arnold of AT&T recognized that the blue glow was caused by ionized gas. Arnold recommended that AT&T purchase the patent, and AT&T followed his recommendation. Arnold developed high-vacuum tubes which

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to evolve any remaining gas from the metal parts. The tube is then sealed and the getter trough or pan, for flash getters, is heated to a high temperature, again by radio frequency induction heating, which causes the getter material to vaporize and react with any residual gas. The vapor is deposited

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In many cases, manufacturers and the military gave tubes designations that said nothing about their purpose (e.g., 1614). In the early days some manufacturers used proprietary names which might convey some information, but only about their products; the KT66 and KT88 were "kinkless tetrodes". Later,

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The internal elements of tubes have always been connected to external circuitry via pins at their base which plug into a socket. Subminiature tubes were produced using wire leads rather than sockets, however, these were restricted to rather specialized applications. In addition to the connections at

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Beam power tubes offer the advantages of a longer load line, less screen current, higher transconductance and lower third harmonic distortion than comparable power pentodes. Beam power tubes can be connected as triodes for improved audio tonal quality but in triode mode deliver significantly reduced

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grid since it is also at a positive voltage, robbing them from the plate current and reducing the amplification of the tube. Since secondary electrons can outnumber the primary electrons over a certain range of plate voltages, the plate current can decrease with increasing plate voltage. This is the

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One variant called a "channel electron multiplier" does not use individual dynodes but consists of a curved tube, such as a helix, coated on the inside with material with good secondary emission. One type had a funnel of sorts to capture the secondary electrons. The continuous dynode was resistive,

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For decades, electron-tube designers tried to augment amplifying tubes with electron multipliers in order to increase gain, but these suffered from short life because the material used for the dynodes "poisoned" the tube's hot cathode. (For instance, the interesting RCA 1630 secondary-emission tube

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into the signal. Leakage current due to internal contamination may also inject noise. Some of these effects make tubes unsuitable for small-signal audio use, although unobjectionable for other purposes. Selecting the best of a batch of nominally identical tubes for critical applications can produce

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is used to absorb gases evolved during tube operation but has only a limited ability to combine with gas. Control of the envelope temperature prevents some types of gassing. A tube with an unusually high level of internal gas may exhibit a visible blue glow when plate voltage is applied. The getter

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As a cost reduction measure, especially in high-volume consumer receivers, all the tube heaters could be connected in series across the AC supply using heaters requiring the same current and with a similar warm-up time. In one such design, a tap on the tube heater string supplied the 6 volts needed

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construction and typically came in 22.5-, 45-, 67.5-, 90-, 120- or 135-volt versions. After the use of B-batteries was phased out and rectified line-power was employed to produce the high voltage needed by tubes' plates, the term "B+" persisted in the US when referring to the high voltage source.

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High-power tubes such as transmitting tubes have packages designed more to enhance heat transfer. In some tubes, the metal envelope is also the anode. The 4CX1000A is an external anode tube of this sort. Air is blown through an array of fins attached to the anode, thus cooling it. Power tubes using

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A considerable amount of heat is produced when tubes operate, from both the filament (heater) and the stream of electrons bombarding the plate. In power amplifiers, this source of heat is greater than cathode heating. A few types of tube permit operation with the anodes at a dull red heat; in other

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to a dull red heat (around 700 °C), which in turn reduced thermal distortion of the tube structure and allowed closer spacing of tube elements. This in turn improved tube gain, since the gain of a triode is inversely proportional to the spacing between grid and cathode. Bare tungsten filaments

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batteries, giving nominal heater voltages of 2 V, 4 V or 6 V. In portable radios, dry batteries were sometimes used with 1.5 or 1 V heaters. Reducing filament consumption improved the life span of batteries. By 1955 towards the end of the tube era, tubes using only 50 mA down to as little as 10 mA

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A superior solution, and one which allowed each cathode to "float" at a different voltage, was that of the indirectly heated cathode: a cylinder of oxide-coated nickel acted as an electron-emitting cathode and was electrically isolated from the filament inside it. Indirectly heated cathodes enable

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was developed whereby the RF transformer connected to the plate (anode) would include an additional winding in the opposite phase. This winding would be connected back to the grid through a small capacitor, and when properly adjusted would cancel the Miller capacitance. This technique was employed

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However C batteries continued to be included in some equipment even when the "A" and "B" batteries had been replaced by power from the AC mains. That was possible because there was essentially no current draw on these batteries; they could thus last for many years (often longer than all the tubes)

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and used it to settle the question of thermionic emission and conduction in a vacuum. Consequently, General Electric started producing hard vacuum triodes (which were branded Pliotrons) in 1915. Langmuir patented the hard vacuum triode, but de Forest and AT&T successfully asserted priority and

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which performs poorly as an insulator in humid conditions. Other reasons for using a top cap include improving stability by reducing grid-to-anode capacitance, improved high-frequency performance, keeping a very high plate voltage away from lower voltages, and accommodating one more electrode than

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between tube elements can destroy the tube. An arc can be caused by applying voltage to the anode (plate) before the cathode has come up to operating temperature, or by drawing excess current through a rectifier, which damages the emission coating. Arcs can also be initiated by any loose material

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base. In 1938 a technique was developed to use an all-glass construction with the pins fused in the glass base of the envelope. This allowed the design of a much smaller tube profile, known as the miniature tube, having seven or nine pins. Making tubes smaller reduced the voltage where they could

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resemble hard vacuum tubes and fit in sockets designed for vacuum tubes. Their distinctive orange, red, or purple glow during operation indicates the presence of gas; electrons flowing in a vacuum do not produce light within that region. These types may still be referred to as "electron tubes" as

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from the plate. In any tube, electrons strike the plate with sufficient energy to cause the emission of electrons from its surface. In a triode this secondary emission of electrons is not important since they are simply re-captured by the plate. But in a tetrode they can be captured by the screen

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When triodes were first used in radio transmitters and receivers, it was found that tuned amplification stages had a tendency to oscillate unless their gain was very limited. This was due to the parasitic capacitance between the plate (the amplifier's output) and the control grid (the amplifier's

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to solid-state models, often due to the way they tend to distort when overdriven. Any amplifier can only accurately amplify a signal to a certain volume; past this limit, the amplifier will begin to distort the signal. Different circuits will distort the signal in different ways; some guitarists

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hardness and proper selection of construction materials are the major influences on tube lifetime. Depending on the material, temperature and construction, the surface material of the cathode may also diffuse onto other elements. The resistive heaters that heat the cathodes may break in a manner

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voltage. Since no current flows through a tube's grid connection, these batteries had no current drain and lasted the longest, usually limited by their own shelf life. The supply from the grid bias battery was rarely, if ever, disconnected when the radio was otherwise switched off. Even after AC

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operating point in the linear region. This was called the idle condition, and the plate current at this point the "idle current". The controlling voltage was superimposed onto the bias voltage, resulting in a linear variation of plate current in response to positive and negative variation of the

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De Forest's original device was made with conventional vacuum technology. The vacuum was not a "hard vacuum" but rather left a very small amount of residual gas. The physics behind the device's operation was also not settled. The residual gas would cause a blue glow (visible ionization) when the

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Cathode depletion is the loss of emission after thousands of hours of normal use. Sometimes emission can be restored for a time by raising heater voltage, either for a short time or a permanent increase of a few percent. Cathode depletion was uncommon in signal tubes but was a frequent cause of

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The heater's failure mode is typically a stress-related fracture of the tungsten wire or at a weld point and generally occurs after accruing many thermal (power on-off) cycles. Tungsten wire has a very low resistance when at room temperature. A negative temperature coefficient device, such as a

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refers to internal vibrations of tube elements which modulate the tube's signal in an undesirable way; sound or vibration pick-up may affect the signals, or even cause uncontrolled howling if a feedback path (with greater than unity gain) develops between a microphonic tube and, for example, a

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Advances using subminiature tubes included the Jaincomp series of machines produced by the Jacobs Instrument Company of Bethesda, Maryland. Models such as its Jaincomp-B employed just 300 such tubes in a desktop-sized unit that offered performance to rival many of the then room-sized machines.

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Early tubes used the filament as the cathode; this is called a "directly heated" tube. Most modern tubes are "indirectly heated" by a "heater" element inside a metal tube that is the cathode. The heater is electrically isolated from the surrounding cathode and simply serves to heat the cathode

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and became generally favored over the simple tetrode. Pentodes are made in two classes: those with the suppressor grid wired internally to the cathode (e.g. EL84/6BQ5) and those with the suppressor grid wired to a separate pin for user access (e.g. 803, 837). An alternative solution for power

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The non-linear operating characteristic of the triode caused early tube audio amplifiers to exhibit harmonic distortion at low volumes. Plotting plate current as a function of applied grid voltage, it was seen that there was a range of grid voltages for which the transfer characteristics were

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Following World War II, tubes intended to be used in series heater strings were redesigned to all have the same ("controlled") warm-up time. Earlier designs had quite-different thermal time constants. The audio output stage, for instance, had a larger cathode and warmed up more slowly than

3318:. This space charge cloud supplies the electrons that create the current flow from the cathode to the anode. As electrons are drawn to the anode during the operation of the circuit, new electrons will boil off the cathode to replenish the space charge. The space charge is an example of an 1689:

led to the development of high-vacuum tubes. After World War I, specialized manufacturers using more economical construction methods were set up to fill the growing demand for broadcast receivers. Bare tungsten filaments operated at a temperature of around 2200 °C. The development of

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Except for diodes, additional electrodes are positioned between the cathode and the plate (anode). These electrodes are referred to as grids as they are not solid electrodes but sparse elements through which electrons can pass on their way to the plate. The vacuum tube is then known as a

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which used an external magnetic deflection coil and was intended for use as an amplifier in telephony equipment. This von Lieben magnetic deflection tube was not a successful amplifier, however, because of the power used by the deflection coil. Von Lieben would later make refinements to

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In a water-cooled tube, the anode voltage appears directly on the cooling water surface, thus requiring the water to be an electrical insulator to prevent high voltage leakage through the cooling water to the radiator system. Water as usually supplied has ions that conduct electricity;

2673:. An electric heater is inserted into the cathode sleeve and insulated from it electrically by a coating of aluminum oxide. This complex construction causes barium and strontium atoms to diffuse to the surface of the cathode and emit electrons when heated to about 780 degrees Celsius. 3346:

electrons driven off the heated cathode are strongly attracted by the positive anode. The control grid(s) in a tube mediate this current flow by combining the small AC signal current with the grid's slightly negative value. When the signal sine (AC) wave is applied to the grid, it

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causing more electrons to be released from that dynode. Those electrons are accelerated toward another dynode at a higher voltage, releasing more secondary electrons; as many as 15 such stages provide a huge amplification. Despite great advances in solid-state photodetectors (e.g.

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In military applications, a high-power vacuum tube can generate a 10–100 megawatt signal that can burn out an unprotected receiver's frontend. Such devices are considered non-nuclear electromagnetic weapons; they were introduced in the late 1990s by both the U.S. and Russia.

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of tubes were limiting factors. "The common wisdom was that valves—which, like light bulbs, contained a hot glowing filament—could never be used satisfactorily in large numbers, for they were unreliable, and in a large installation too many would fail in too short a time".

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coating. This "cathode interface" is a high-resistance layer (with some parallel capacitance) which greatly reduces the cathode current when the tube is switched into conduction mode. Elimination of silicon from the heater wire alloy (and more frequent replacement of the

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The filaments require constant and often considerable power, even when amplifying signals at the microwatt level. Power is also dissipated when the electrons from the cathode slam into the anode (plate) and heat it; this can occur even in an idle amplifier due to the

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to the surface to replace them. Such thoriated tungsten cathodes usually deliver lifetimes in the tens of thousands of hours. The end-of-life scenario for a thoriated-tungsten filament is when the carbonized layer has mostly been converted back into another form of

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sufficiently for thermionic emission of electrons. The electrical isolation allows all the tubes' heaters to be supplied from a common circuit (which can be AC without inducing hum) while allowing the cathodes in different tubes to operate at different voltages.

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is a special-purpose tube filled with low-pressure gas or mercury vapor. Like vacuum tubes, it contains a hot cathode and an anode, but also a control electrode which behaves somewhat like the grid of a triode. When the control electrode starts conduction, the

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necessary to ensure linearity and low distortion. In a power amplifier, this heating can be considerable and can destroy the tube if driven beyond its safe limits. Since the tube contains a vacuum, the anodes in most small and medium power tubes are cooled by

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safely operate, and also reduced the power dissipation of the filament. Miniature tubes became predominant in consumer applications such as radio receivers and hi-fi amplifiers. However, the larger older styles continued to be used especially as higher-power

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When a cathode is heated and reaches an operating temperature around 1,050 K (780 °C; 1,430 °F), free electrons are driven from its surface. These free electrons form a cloud in the empty space between the cathode and the anode, known as the

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have also been used. A first version of the 6L6 used a metal envelope sealed with glass beads, while a glass disk fused to the metal was used in later versions. Metal and ceramic are used almost exclusively for power tubes above 2 kW dissipation. The

2508:'s main Northern Ireland transmitter at Lisnagarvey. The valve was in service from 1935 until 1961 and had a recorded life of 232,592 hours. The BBC maintained meticulous records of their valves' lives with periodic returns to their central valve stores. 2491:) and glasses had been developed for light bulbs that expanded and contracted in similar amounts, as temperature changed. These made it easy to construct an insulating envelope of glass, while passing connection wires through the glass to the electrodes. 1648:. The nuvistor was developed to compete with the early transistors and operated at higher frequencies than those early transistors could. The small size supported especially high-frequency operation; nuvistors were used in aircraft radio transceivers, 1164:, avoiding the need for a separate negative power supply. For cathode biasing, a relatively low-value resistor is connected between the cathode and ground. This makes the cathode positive with respect to the grid, which is at ground potential for DC. 2547:

between the tube electrodes and cause overheating of the electrodes, producing more gas, damaging the tube and possibly other components due to excess current. To avoid these effects, the residual pressure within the tube must be low enough that the

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To meet the reliability requirements of the 1951 US digital computer Whirlwind, "special-quality" tubes with extended life, and a long-lasting cathode in particular, were produced. The problem of short lifetime was traced largely to evaporation of

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Commercial packaging for vacuum tubes used in the latter half of the 20th century including boxes for individual tubes (bottom right), sleeves for rows of the boxes (left), and bags that smaller tubes would be put in by a store upon purchase (top

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because it passed current in only one direction. The cathode was a carbon lamp filament, heated by passing current through it, that produced thermionic emission of electrons. Electrons that had been emitted from the cathode were attracted to the

2627:. An extremely thin (molecular) layer of thorium atoms forms on the outside of the wire's carbonized layer and, when heated, serve as an efficient source of electrons. The thorium slowly evaporates from the wire surface, while new thorium atoms 2011:

The anode is often treated to make its surface emit more infrared energy. High-power amplifier tubes are designed with external anodes that can be cooled by convection, forced air or circulating water. The water-cooled 80 kg, 1.25 MW

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for the dial light. By deriving the high voltage from a half-wave rectifier directly connected to the AC mains, the heavy and costly power transformer was eliminated. This also allowed such receivers to operate on direct current, a so-called

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introduced mains-frequency (50 or 60 Hz) hum into audio stages. The invention of the "equipotential cathode" reduced this problem, with the filaments being powered by a balanced AC power transformer winding having a grounded center tap.

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To avoid the warm-up delay, "instant on" television receivers passed a small heating current through their tubes even when the set was nominally off. At switch on, full heating current was provided and the set would play almost immediately.

1157:, for which the letter denotes its size and shape). The C battery's positive terminal was connected to the cathode of the tubes (or "ground" in most circuits) and whose negative terminal supplied this bias voltage to the grids of the tubes. 1988:

The requirements for heat removal can significantly change the appearance of high-power vacuum tubes. High power audio amplifiers and rectifiers required larger envelopes to dissipate heat. Transmitting tubes could be much larger still.

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Gas and ions within the tube contribute to grid current which can disturb operation of a vacuum-tube circuit. Another effect of overheating is the slow deposit of metallic vapors on internal spacers, resulting in inter-element leakage.

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of an electron is much longer than the size of the tube (so an electron is unlikely to strike a residual atom and very few ionized atoms will be present). Commercial vacuum tubes are evacuated at manufacture to about 0.000001 mmHg

853:, the Fleming valve offered advantage, particularly in shipboard use, over the difficulty of adjustment of the crystal detector and the susceptibility of the crystal detector to being dislodged from adjustment by vibration or bumping. 2335:, eliminating the need for a third power supply voltage; this became practical with tubes using indirect heating of the cathode along with the development of resistor/capacitor coupling which replaced earlier interstage transformers. 1959:

air-defense computer system. By the late 1950s, it was routine for special-quality small-signal tubes to last for hundreds of thousands of hours if operated conservatively. This increased reliability also made mid-cable amplifiers in

2003:

Tubes which generate relatively little heat, such as the 1.4-volt filament directly heated tubes designed for use in battery-powered equipment, often have shiny metal anodes. 1T4, 1R5 and 1A7 are examples. Gas-filled tubes such as

3009:

produced by giant solar flares. This property kept them in use for certain military applications long after more practical and less expensive solid-state technology was available for the same applications, as for example with the

936:

Thus a change of voltage applied to the grid, requiring very little power input to the grid, could make a change in the plate current and could lead to a much larger voltage change at the plate; the result was voltage and power

3713:

The electronics age may be said to have been ushered in with the invention of the vacuum diode valve in 1902 by the Briton John Fleming (himself coining the word 'electronics'), the immediate application being in the field of

5804: 1393:). Constraints due to the number of external pins (leads) often forced the functions to share some of those external connections such as their cathode connections (in addition to the heater connection). The RCA Type 55 is a 1695:

remain in use in small transmitting tubes but are brittle and tend to fracture if handled roughly—e.g. in the postal services. These tubes are best suited to stationary equipment where impact and vibration is not present.

2835:

and industrial heating. Traveling-wave tubes (TWTs) are very good amplifiers and are even used in some communications satellites. High-powered klystron amplifier tubes can provide hundreds of kilowatts in the UHF range.

1703:

The desire to power electronic equipment using AC mains power faced a difficulty with respect to the powering of the tubes' filaments, as these were also the cathode of each tube. Powering the filaments directly from a

657:, etc., depending on the number of grids. A triode has three electrodes: the anode, cathode, and one grid, and so on. The first grid, known as the control grid, (and sometimes other grids) transforms the diode into a 529:. Tubes were a frequent cause of failure in electronic equipment, and consumers were expected to be able to replace tubes themselves. In addition to the base terminals, some tubes had an electrode terminating at a 1635:

Sub-miniature tubes with a size roughly that of half a cigarette were used in consumer applications as hearing-aid amplifiers. These tubes did not have pins plugging into a socket but were soldered in place. The

2482:

in the air reacts chemically with the hot filament or cathode, quickly ruining it. Designers developed tube designs that sealed reliably. This was why most tubes were constructed of glass. Metal alloys (such as

2089:

The generic name " valve" used in the UK derives from the unidirectional current flow allowed by the earliest device, the thermionic diode emitting electrons from a heated filament, by analogy with a non-return

1225:

in 1919. He showed that the addition of an electrostatic shield between the control grid and the plate could solve the problem. This design was refined by Hull and Williams. The added grid became known as the

1298:

of the pentode was usually connected to the cathode and its negative voltage relative to the anode repelled secondary electrons so that they would be collected by the anode instead of the screen grid. The term

981:

process in Berlin, Germany. Tigerstedt's innovation was to make the electrodes concentric cylinders with the cathode at the centre, thus greatly increasing the collection of emitted electrons at the anode.

1251:

The useful region of operation of the screen grid tube (tetrode) as an amplifier is limited to anode potentials in the straight portions of the characteristic curves greater than the screen grid potential.

2027:

The screen grid may also generate considerable heat. Limits to screen grid dissipation, in addition to plate dissipation, are listed for power devices. If these are exceeded then tube failure is likely.

2450:" by gas molecules from other elements in the tube, which reduce its ability to emit electrons. Trapped gases or slow gas leaks can also damage the cathode or cause plate (anode) current runaway due to 713:, such tubes were only used in scientific research or as novelties. The groundwork laid by these scientists and inventors, however, was critical to the development of subsequent vacuum tube technology. 2094:

in a water pipe. The US names "vacuum tube", "electron tube", and "thermionic tube" all simply describe a tubular envelope which has been evacuated ("vacuum"), has a heater and controls electron flow.

3388:

Every tube has a unique set of such characteristic curves. The curves graphically relate the changes to the instantaneous plate current driven by a much smaller change in the grid-to-cathode voltage (

2595:

Getters act by chemically combining with residual or infiltrating gases, but are unable to counteract (non-reactive) inert gases. A known problem, mostly affecting valves with large envelopes such as

2048:

Triode tube type GS-9B; designed for use at radio frequencies up to 2000 MHz and rated for 300 watts anode power dissipation. The finned heat sink provides conduction of heat from anode to air stream.

641:

in klystrons) at ground potential to facilitate cooling, particularly with water, without high-voltage insulation. These tubes instead operate with high negative voltages on the filament and cathode.

627:

through the glass envelope. In some special high power applications, the anode forms part of the vacuum envelope to conduct heat to an external heat sink, usually cooled by a blower, or water-jacket.

4916: 2736:

Tubes on standby for long periods, with heater voltage applied, may develop high cathode interface resistance and display poor emission characteristics. This effect occurred especially in pulse and

1059:) is defined as the change in the plate(anode)/cathode current divided by the corresponding change in the grid to cathode voltage, with a constant plate(anode) to cathode voltage. Typical values of 802:

as scientific advisor in 1899. Fleming had been engaged as scientific advisor to Edison Telephone (1879), as scientific advisor at Edison Electric Light (1882), and was also technical consultant to

2171:, after which the control electrode can no longer stop the current; the tube "latches" into conduction. Removing anode (plate) voltage lets the gas de-ionize, restoring its non-conductive state. 1375:". Octodes, such as the 7A8, were rarely used in the United States, but much more common in Europe, particularly in battery operated radios where the lower power consumption was an advantage. 251:

devices, which are smaller, safer, cooler, and more efficient, reliable, durable, and economical than thermionic tubes. Beginning in the mid-1960s, thermionic tubes were being replaced by the

2994:

devices in most amplifying, switching, and rectifying applications, there are certain exceptions. In addition to the special functions noted above, tubes still have some niche applications.

2804:

Most small signal vacuum tube devices have been superseded by semiconductors, but some vacuum tube electronic devices are still in common use. The magnetron is the type of tube used in all

2854:(CRT) is a vacuum tube used particularly for display purposes. Although there are still many televisions and computer monitors using cathode-ray tubes, they are rapidly being replaced by 2687:

pins. Stress may accumulate if a metal shield or other object presses on the tube envelope and causes differential heating of the glass. Glass may also be damaged by high-voltage arcing.

2215:

equipment may use a focused cathode and a rotating anode to dissipate the large amounts of heat thereby generated. These are housed in an oil-filled aluminum housing to provide cooling.

2408:

Where the mains voltage was in the 100–120 V range, this limited voltage proved suitable only for low-power receivers. Television receivers either required a transformer or could use a

1716:

Tubes designed for high gain audio applications may have twisted heater wires to cancel out stray electric fields, fields that could induce objectionable hum into the program material.

3636: 2710:

inside the tube, or by excess screen voltage. An arc inside the tube allows gas to evolve from the tube materials, and may deposit conductive material on internal insulating spacers.

2331:

power supplies became commonplace, some radio sets continued to be built with C batteries, as they would almost never need replacing. However more modern circuits were designed using

2186:; some can switch thousands of amperes. Thyratrons containing hydrogen have a very consistent time delay between their turn-on pulse and full conduction; they behave much like modern 1131: 5800: 1272:

which can itself cause instability. Another undesirable consequence of secondary emission is that screen current is increased, which may cause the screen to exceed its power rating.

2703:

if the filament sags, causing internal arcing. Excess heater-to-cathode voltage in indirectly heated cathodes can break down the insulation between elements and destroy the heater.

3342:. Due to the high voltage placed on the anode, a relatively small anode current can represent a considerable increase in energy over the value of the original signal voltage. The 2808:. In spite of the advancing state of the art in power semiconductor technology, the vacuum tube still has reliability and cost advantages for high-frequency RF power generation. 2024:, a good insulator, is required. Such systems usually have a built-in water-conductance monitor which will shut down the high-tension supply if the conductance becomes too high. 193:. It contains only a heated electron-emitting cathode and an anode. Electrons can flow in only one direction through the device—from the cathode to the anode. Adding one or more 2690:

Tube heaters may also fail without warning, especially if exposed to over voltage or as a result of manufacturing defects. Tube heaters do not normally fail by evaporation like

1844:). Colossus was able to break in a matter of hours messages that had previously taken several weeks; it was also much more reliable. Colossus was the first use of vacuum tubes 2073:

between the grid and the plate leads. Tube caps were also used for the plate (anode) connection, particularly in transmitting tubes and tubes using a very high plate voltage.

1669:

The earliest vacuum tubes strongly resembled incandescent light bulbs and were made by lamp manufacturers, who had the equipment needed to manufacture glass envelopes and the

1420:

The introduction of the miniature tube base (see below) which can have 9 pins, more than previously available, allowed other multi-section tubes to be introduced, such as the

533:. The principal reason for doing this was to avoid leakage resistance through the tube base, particularly for the high impedance grid input. The bases were commonly made with 5471:

Blank, M.; Borchard, P.; Cauffman, S.; Felch, K.; Rosay, M.; Tometich, L. (1 June 2013). "Experimental demonstration of a 527 GHZ gyrotron for dynamic nuclear polarization".

4496:

is the amount the signal at the control grid is increased in amplitude after passing through the tube, which is also referred to as the Greek letter μ (mu) or voltage gain (V

2942:), the single-photon detection capability of photomultiplier tubes makes this vacuum tube device excel in certain applications. Such a tube can also be used for detection of 1012:' and later the English type 'R' which were in widespread use by the allied military by 1916. Historically, vacuum levels in production vacuum tubes typically ranged from 10 2498:

is universally a sign of an overloaded tube. However, some large transmitting tubes are designed to operate with their anodes at red, orange, or in rare cases, white heat.

2077:

this cooling scheme are available up to 150 kW dissipation. Above that level, water or water-vapor cooling are used. The highest-power tube currently available is the

4440: 2756:

Vacuum tubes may develop defects in operation that make an individual tube unsuitable in a given device, although it may perform satisfactorily in another application.

2997:

In general, vacuum tubes are much less susceptible than corresponding solid-state components to transient overvoltages, such as mains voltage surges or lightning, the

2763:

loudspeaker. Leakage current between AC heaters and the cathode may couple into the circuit, or electrons emitted directly from the ends of the heater may also inject

2099: 3246:

In the early years of the 21st century there has been renewed interest in vacuum tubes, this time with the electron emitter formed on a flat silicon substrate, as in

2866:), although traditional analog scopes (dependent upon CRTs) continue to be produced, are economical, and preferred by many technicians. At one time many radios used " 2081:

4CM2500KG, a forced water-cooled power tetrode capable of dissipating 2.5 megawatts. By comparison, the largest power transistor can only dissipate about 1 kilowatt.

7524: 818:, but the magnetic detector only provided an audio frequency signal to a telephone receiver. A reliable detector that could drive a printing instrument was needed. 947:) for such a three-electrode version of his original Audion for use as an electronic amplifier in radio communications. This eventually became known as the triode. 1068:

for a small-signal vacuum tube are 1 to 10 millisiemens. It is one of the three 'constants' of a vacuum tube, the other two being its gain μ and plate resistance

2724:

Overheating of internal parts, such as control grids or mica spacer insulators, can result in trapped gas escaping into the tube; this can reduce performance. A

2274:

provided the voltages required by tubes in early radio sets. Three different voltages were generally required, using three different batteries designated as the

2636:

and emission begins to drop off rapidly; a complete loss of thorium has never been found to be a factor in the end-of-life in a tube with this type of emitter.

1905:) allowed the production of tubes that were reliable enough for the Whirlwind project. High-purity nickel tubing and cathode coatings free of materials such as 1378:

To further reduce the cost and complexity of radio equipment, two separate structures (triode and pentode for instance) can be combined in the bulb of a single

5663: 5349:, Fitzgerald, William V., "Power supply stabilization circuit with separate AC/DC negative feedback paths", published 1995-10-31, assigned to 3837: 2415:

Transformer-less power supplies required safety precautions in their design to limit the shock hazard to users, such as electrically insulated cabinets and an

4923: 1808: 1435:

electrodes which deflected the current towards either of two anodes. They were sometimes known as the 'sheet beam' tubes and used in some color TV sets for

2966:

consists of an array of single stage electron multipliers over an image plane; several of these can then be stacked. This can be used, for instance, as an

1255:

However, the useful region of operation of the screen grid tube as an amplifier was limited to plate voltages greater than the screen grid voltage, due to

6024: 2698:

when the heater is first energized causes stress in the heater and can be avoided by slowly warming the heaters, gradually increasing current with a NTC

1424:/ECF82 triode-pentode, quite popular in television receivers. The desire to include even more functions in one envelope resulted in the General Electric 1492:

grid, reducing control grid current. This design helps to overcome some of the practical barriers to designing high-power, high-efficiency power tubes.

278:, and amplifiers for electric musical instruments such as guitars (for desired effects, such as "overdriving" them to achieve a certain sound or tone). 3808: 2423:

was a power cord ending in the special socket used by the safety interlock; servicers could then power the device with the hazardous voltages exposed.

970:

were tested in the summer of 1913 on AT&T's long-distance network. The high-vacuum tubes could operate at high plate voltages without a blue glow.

236:

for computing, it was the invention of the thermionic vacuum tube that made these technologies widespread and practical, and created the discipline of

4326: 2608: 5959: 1188:

radio during the 1920s. However, neutralization required careful adjustment and proved unsatisfactory when used over a wide range of frequencies.

898:

In the 19th century, telegraph and telephone engineers had recognized the need to extend the distance that signals could be transmitted. In 1906,

6109: 5426: 1431:

Some otherwise conventional tubes do not fall into standard categories; the 6AR8, 6JH8 and 6ME8 have several common grids, followed by a pair of

200:

These devices became a key component of electronic circuits for the first half of the twentieth century. They were crucial to the development of

5007: 4874:. Proceedings of Symposium on Improved Quality Electronic Components. Vol. 1. Radio-Television Manufacturers Association. pp. 222–233. 4354: 4782: 3400:

The V-I characteristic depends upon the size and material of the plate and cathode. Express the ratio between voltage plate and plate current.

2098:

consumer tubes were given names that conveyed some information, with the same name often used generically by several manufacturers. In the US,

4466: 2168: 1413:

is a dual "high mu" (high voltage gain) triode in a miniature enclosure, and became widely used in audio signal amplifiers, instruments, and

130:, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the 5917:

Philips Technical Library. Books published in the UK in the 1940s and 1950s by Cleaver Hume Press on design and application of vacuum tubes.

4169: 2419:

tying the power cord to the cabinet back, so the line cord was necessarily disconnected if the user or service person opened the cabinet. A

4001: 3083: 1389:

By 1940 multisection tubes had become commonplace. There were constraints, however, due to patents and other licensing considerations (see

1240:

to ground with a capacitor of low impedance at the frequencies to be amplified. This arrangement substantially decouples the plate and the

5391: 7159: 2543:

when struck by an electron and can adversely affect the cathode, reducing emission. Larger amounts of residual gas can create a visible

2008:

may also use a shiny metal anode since the gas present inside the tube allows for heat convection from the anode to the glass enclosure.

5070: 2895:

effect, due to the high voltage, is used for bunching the electrons. Gyrotrons can generate very high powers (hundreds of kilowatts).,

6002: 5777: 2771:

Tube pins can develop non-conducting or high resistance surface films due to heat or dirt. Pins can be cleaned to restore conductance.

2576:

being the most common. For glass tubes, while the tube envelope is being evacuated, the internal parts except the getter are heated by

4392: 4259: 6983: 5443: 4818:. Symposium on Commercially Available General-Purpose Electronic Digital Computers of Moderate Price. The Pentagon, Washington, D.C. 1405:

in early AC powered radios. These sets often include the 53 Dual Triode Audio Output. Another early type of multi-section tube, the

4086: 2954:

tube widely used in television studios prior to the development of modern CCD arrays also used multistage electron multiplication.

2494:

When a vacuum tube is overloaded or operated past its design dissipation, its anode (plate) may glow red. In consumer equipment, a

1766:(who operated telephone exchanges). Flowers was also a pioneer of using tubes as very fast (compared to electromechanical devices) 4371: 1719:

Heaters may be energized with either alternating current (AC) or direct current (DC). DC is often used where low hum is required.

6624: 5331: 4309: 3595: 3292:

As of 2014, NASA's Ames Research Center was reported to be working on vacuum-channel transistors produced using CMOS techniques.

2740:, where tubes had no plate current flowing for extended times. Tubes designed specifically for this mode of operation were made. 5644:"... geomagnetic storms, on occasion, can induce more powerful pulses than the E3 pulse from even megaton type nuclear weapons." 2903:, are highly relativistic vacuum tubes driven by high-energy particle accelerators. Thus, these are sorts of cathode-ray tubes. 1290:

The dynatron region of the screen grid tube was eliminated by adding a grid between the screen grid and the plate to create the

425:

Vacuum tubes may have other components and functions than those described above, and are described elsewhere. These include as

1409:, is a "dual triode" which performs the functions of two triode tubes while taking up half as much space and costing less. The 803: 2174:

Some thyratrons can carry large currents for their physical size. One example is the miniature type 2D21, often seen in 1950s

1217:

To combat the stability problems of the triode as a radio frequency amplifier due to grid-to-plate capacitance, the physicist

5886: 5488: 5064: 4764: 4752: 4486: 4423: 4108: 3706: 1933: 1841: 6073: 2827:, combine magnetic and electrostatic effects. These are efficient (usually narrow-band) RF generators and still find use in 2748:. Usable life of this expensive component was sometimes extended by fitting a boost transformer to increase heater voltage. 7442: 6541: 3509: 2412:

circuit. Where 230 V nominal mains voltage was used, television receivers as well could dispense with a power transformer.

2116: 5829: 5637: 3780: 3214: 2539:

vacuum, from X-ray terminology) to avoid the consequences of generating positive ions within the tube. Residual gas atoms

761:, such tubes were instrumental in long-distance telephony (such as the first coast-to-coast telephone line in the US) and 665:(JFET), although vacuum tubes typically operate at over a hundred volts, unlike most semiconductors in most applications. 6322: 6102: 3139: 2069:

the base of the tube, many early triodes connected the grid using a metal cap at the top of the tube; this reduces stray

4667: 4444: 4150: 4071: 3186: 2290:

or LT (low-tension) battery provided the filament voltage. Tube heaters were designed for single, double or triple-cell

5874: 5455: 4899: 4208: 3763: 3738: 3620: 3589: 1749:

Vacuum tubes used as switches made electronic computing possible for the first time, but the cost and relatively short

4027: 3930: 2401:. Many different US consumer AM radio manufacturers of the era used a virtually identical circuit, given the nickname 2236:, rather than thermionic emission, to generate and amplify electrical signals. Nuclear medicine imaging equipment and 6305: 6201: 5933:, RC15, RC26 (1947, 1968) Issued every two years, contains details of the technical specs of the tubes that RCA sold. 5864: 5580: 5274: 4692: 4249:

J.Jenkins and W.H.Jarvis, "Basic Principles of Electronics, Volume 1 Thermionics", Pergamon Press (1966), Ch.1.10 p.9

3862: 3831: 3233: 1956: 1652:

television tuners, and some HiFi FM radio tuners (Sansui 500A) until replaced by high-frequency capable transistors.

17: 3987: 3262:). With these devices, electrons are field-emitted from a large number of closely spaced individual emission sites. 6445: 6172: 5922: 4554: 4056: 3682: 3613:

Fundamental Amplifier Techniques with Electron Tubes: Theory and Practice with Design Methods for Self Construction

3193: 1439: 886:

Triodes as they evolved over some 45 years of tube manufacture, from the RE16 in 1918 to a 1960s era miniature tube

662: 213: 5086: 2929:

whose sensitivity is greatly increased through the use of electron multiplication. This works on the principle of

2201:, which is used for rapid high-voltage switching. Krytrons are used to initiate the detonations used to set off a 341:, and so forth, which have multiple additional functions made possible by the additional controllable electrodes. 7152: 6493: 6292: 4040: 2194:

due to their functional similarity to thyratrons. Hydrogen thyratrons have long been used in radar transmitters.

5320: 5308: 5296: 5249: 5184: 4615: 4133: 2977:

electron optics of the wideband electron gun could not provide enough current to directly excite the phosphor.)

2891:

or vacuum masers, used to generate high-power millimeter band waves, are magnetic vacuum tubes in which a small

2211:

are used in medical imaging among other uses. X-ray tubes used for continuous-duty operation in fluoroscopy and

821:

As a result of experiments conducted on Edison effect bulbs, Fleming developed a vacuum tube that he termed the

7509: 7437: 6095: 5216: 4632: 3669: 3171: 2504:

The longest recorded valve life was earned by a Mazda AC/P pentode valve (serial No. 4418) in operation at the

1961: 1534:

vacuum tubes, though are always filled with gas at less than sea-level atmospheric pressure. Types such as the

197:

within the tube allows the current between the cathode and anode to be controlled by the voltage on the grids.

4987: 1089: 449:(which rely on electron flow through a vacuum where electron emission from the cathode depends on energy from 3886: 3504: 3200: 2939: 2237: 1728: 929:(anode), he discovered the ability of the resulting device to amplify signals. As the voltage applied to the 721: 5801:"The vacuum tube strikes back: NASA's tiny 460GHz vacuum transistor that could one day replace silicon FETs" 5743: 2446:

One reliability problem of tubes with oxide cathodes is the possibility that the cathode may slowly become "

6524: 6276: 5350: 3167: 2187: 2107:

electrodes, or two sets of electrodes in a single envelope—a double triode, for example). For example, the

1770:. Later work confirmed that tube unreliability was not as serious an issue as generally believed; the 1946 1559:

Miniature tube (right) compared to the older octal style. Not including pins, the larger tube, a 5U4GB, is

6059: 5721: 790:

At the end of the 19th century, radio or wireless technology was in an early stage of development and the

7519: 7514: 7504: 6328: 6265: 5625:

Broad, William J. "Nuclear Pulse (I): Awakening to the Chaos Factor", Science. 29 May 1981 212: 1009–1012

2863: 1044: 414: 286: 285:

are similar devices, but containing a gas, typically at low pressure, which exploit phenomena related to

6021: 3413:

AC plate resistance of the plate—resistance of the path between anode and cathode of alternating current

3182: 1275:

The otherwise undesirable negative resistance region of the plate characteristic was exploited with the

1236:. The screen grid is operated at a positive voltage significantly less than the plate voltage and it is 724:, it was Thomas Edison's apparently independent discovery of the phenomenon in 1883, referred to as the 7145: 6988: 6535: 2875: 1443: 917:

is credited with inventing the triode tube in 1907 while experimenting to improve his original (diode)

5423: 5346: 3041:

provide amplification at power levels unattainable using current semiconductor devices. The household

2713:

Tube rectifiers have limited current capability and exceeding ratings will eventually destroy a tube.

2527: 2361:

Battery replacement was a major operating cost for early radio receiver users. The development of the

2182:. A cold-cathode version of the thyratron, which uses a pool of mercury for its cathode, is called an 1902: 765:, and introduced a far superior and versatile technology for use in radio transmitters and receivers. 7452: 6742: 6456: 6299: 6184: 5000: 3945:

Guarnieri, M. (2012). "The age of vacuum tubes: Early devices and the rise of radio communications".

3534: 3098:

prefer the distortion characteristics of vacuum tubes. Most popular vintage models use vacuum tubes.

2212: 1390: 958: 434: 4790: 2947: 386: 7499: 7301: 6751: 6609: 6461: 6317: 4478: 3410:

DC plate resistance of the plate—resistance of the path between anode and cathode of direct current

3086:, performance when overdriven, and ability to replicate prior-era tube-based recording are prized: 2933:, whereby a single electron emitted by the photocathode strikes a special sort of anode known as a 1336: 1283:

to oscillate. The dynatron oscillator operated on the same principle of negative resistance as the

954: 4200: 1247: 6762: 6482: 6281: 5840:

Basic theory and application of Electron tubes Department of the army and air force, AGO 2244-Jan

4165: 3255: 3160: 3130:

technology soon took the place of CRTs in these devices. By 2010, most CRT production had ended.

2991: 2691: 2416: 1213:

symbol. From top to bottom: plate (anode), screen grid, control grid, cathode, heater (filament).

1153:. Many early radio sets had a third battery called the "C battery" (unrelated to the present-day 542: 429:, which create a beam of electrons for display purposes (such as the television picture tube, in 248: 4569: 4076:. Annapolis, MD: United States Naval Institute. p. 124 fig. 84; pp. 131, 132. Retrieved Nov 2021 4005: 3896: 2307:

Most of the rest of the English speaking world refers to this supply as just HT (high tension).

2138:

Some special-purpose tubes are constructed with particular gases in the envelope. For instance,

1360: 1356: 7432: 6931: 6498: 6363: 6339: 3823:

Innovation and the Communications Revolution: From the Victorian Pioneers to Broadband Internet

3524: 3286: 3124: 3049:

tube to efficiently generate hundreds of watts of microwave power. Solid-state devices such as

2885:

is a type of cathode-ray tube that generates X-rays when high voltage electrons hit the anode.

2386: 2139: 2131: 2103: 1996:

from the anode (plate) as infrared radiation, and by convection of air over the tube envelope.

1535: 1398: 1304: 810:, a device that extracts information from a modulated radio frequency. Marconi had developed a 706: 5054: 4813: 2874:

to indicate signal strength or input level in a tape recorder. A modern indicator device, the

1836:(BP) during World War II to substantially speed up the task of breaking the German high level 594:) will convert alternating current (AC) to pulsating DC. Diodes can therefore be used in a DC 7494: 7331: 7000: 6952: 6773: 6589: 6504: 6435: 6271: 6037:—1972 AES paper on audible differences in sound quality between vacuum tubes and transistors. 4760: 3821: 3351:

on this negative value, driving it both positive and negative as the AC signal wave changes.

3250:

technology. This subject is now called vacuum nanoelectronics. The most common design uses a

2998: 2398: 2343: 2291: 2271: 2266: 2241: 1691: 993: 950: 762: 229: 146: 5988: 5769: 5232: 5135: 4470: 4192: 3852: 3338:

applied to the control grid, while the resulting amplified signal appears at the anode as a

2962:

and its ends were connected to enough voltage to create repeated cascades of electrons. The

2310: 1507:, and use a pentode graphic symbol instead of a graphic symbol showing beam forming plates. 1279:

circuit to produce a simple oscillator only requiring connection of the plate to a resonant

7468: 7447: 7427: 7366: 7306: 7232: 7074: 6818: 6713: 6487: 6380: 6234: 6195: 6126: 6118: 5686: 5595: 5525: 4388: 3529: 3498: 3026: 3017:

Vacuum tubes are practical alternatives to solid-state devices in generating high power at

2922: 2912: 2892: 2858:

whose quality has greatly improved even as their prices drop. This is also true of digital

2721:

Degenerative failures are those caused by the slow deterioration of performance over time.

2588:. Large transmitting and specialized tubes often use more exotic getter materials, such as 2229: 2225: 1993: 1922: 1889: 1863: 1779: 1750: 1649: 1432: 799: 783: 758: 731: 624: 538:

allowed by the base. There was even an occasional design that had two top cap connections.

446: 244: 190: 166: 127: 894:

Triode symbol. From top to bottom: plate (anode), control grid, cathode, heater (filament)

379: 8: 7391: 7280: 7182: 6794: 6702: 6594: 6430: 6407: 5926:, 1953 (4th Edition). Contains chapters on the design and application of receiving tubes. 5120: 4471: 4193: 3331: 3259: 3207: 3038: 2896: 2816: 2641: 2531:

Dead vacuum fluorescent display (Air has leaked in and the getter spot has become white.)

1829: 1763: 1394: 1348: 1329: 1276: 1269: 1139:

To use this range, a negative bias voltage had to be applied to the grid to position the

717: 603: 563: 549: 546: 534: 514: 454: 430: 375: 233: 103: 6082: 5936:

Shiers, George, "The First Electron Tube", Scientific American, March 1969, p. 104.

5690: 5599: 5529: 4274:

Guarnieri, M. (2012). "The age of vacuum tubes: the conquest of analog communications".

3890: 2568:

To prevent gases from compromising the tube's vacuum, modern tubes are constructed with

2354:"Cheater cord" redirects here. For the three-prong to two-prong mains plug adapter, see 814:, which was less responsive to natural sources of radio frequency interference than the 566:. This can produce a controllable unidirectional current though the vacuum known as the 392:

by application (receiving, transmitting, amplifying or switching, rectification, mixing)

274:, and high end audio amplifiers, which many audio enthusiasts prefer for their "warmer" 7099: 6959: 6667: 6634: 6450: 6334: 6312: 5941: 5702: 5556: 5513: 5494: 5168: 4718: 4585: 4368: 4291: 3962: 3477: 3247: 3053:

are promising replacements, but are very expensive and in early stages of development.

3030: 3022: 2963: 2943: 2930: 2855: 2362: 2245: 2233: 1488: 1256: 1218: 522: 55:

vacuum tubes, mostly miniature style, some with top cap connections for higher voltages

30:

This article is about the electronic device. For experiments in an evacuated pipe, see

5677:

Keeports, David (9 February 2017). "The warm, rich sound of valve guitar amplifiers".

5152: 3576: 2478:

Another important reliability problem is caused by air leakage into the tube. Usually

1925:

the tubes during offline maintenance periods to bring on early failure of weak units.

1428:

which has 12 pins. A typical example, the 6AG11, contains two triodes and two diodes.

1160:

Later circuits, after tubes were made with heaters isolated from their cathodes, used

7401: 7386: 7094: 7015: 6906: 6858: 6687: 6614: 6576: 6045: 5947: 5882: 5860: 5561: 5543: 5484: 5451: 5212: 5190: 5060: 4949: 4895: 4748: 4688: 4482: 4419: 4204: 3935:. London, UK: Marshall, Morgan & Scott, Ltd. pp. 136 - 143. Retrieved Nov. 2021. 3868: 3858: 3827: 3759: 3734: 3702: 3665: 3616: 3585: 3006: 3002: 2967: 2951: 2580: 2460: 2447: 2402: 2370: 2366: 1813: 1803: 1759: 1705: 1674: 1544: 1372: 1013: 899: 811: 795: 739: 619: 330: 6054: 5706: 5655: 5498: 4722: 4511: 4295: 3966: 2463:

filaments, but rarely do, since they operate at much lower temperatures than lamps.

1555: 7351: 7291: 6810: 6757: 6584: 6223: 5955: 5694: 5603: 5551: 5533: 5476: 5038: 4974: 4710: 4539: 4525: 4283: 3954: 3792: 3436:—Instrument for converting alternating electric currents into continuous currents ( 3358:(see example above,) which visually display how the output current from the anode ( 3120: 3112: 2851: 2845: 2745: 2633: 2596: 1976:

The anode (plate) of this transmitting triode has been designed to dissipate up to

1945: 1767: 1446: 1414: 1340: 1237: 1032: 989: 977:

significantly improved on the original triode design in 1914, while working on his

966: 903: 850: 807: 735: 634: 426: 418: 302: 256: 225: 76: 6619: 6050: 5608: 5029:, J. L. Heilbron, Oxford University Press 2003, 9780195112290, "valve, thermionic" 4600: 4101: 3660:

John Algeo, "Types of English heteronyms", p. 23 in, Edgar Werner Schneider (ed),

2796:

Vacuum tubes can be tested outside of their circuitry using a vacuum tube tester.

1660: 7529: 7212: 7207: 7087: 7020: 6873: 6604: 6514: 6358: 6077: 6070: 5641: 5430: 5368: 5090: 4768: 4705:

Guarnieri, M. (2012). "The age of Vacuum Tubes: Merging with Digital Computing".

4671: 4375: 4225: 3549: 3123:

at the start of the 21st century. However, rapid advances and falling prices of

3094: 3090:

equipment, musical instrument amplifiers, and devices used in recording studios.

3076: 3050: 3018: 2737: 2670: 2662: 2577: 2409: 2021: 1783: 1686: 1519: 1480: 1344: 1295: 1047:, in which the controlling signal is a current and the output is also a current. 985: 974: 926: 828: 791: 698: 349: 282: 221: 6245: 6015: 5480: 4649: 4058:

Instrument for Converting Alternating Electric Currents into Continuous Currents

3422:

Size of electrostatic field is the size between two or more plates in the tube.

3285:

communication. As of 2012, they were being studied for possible applications in

2373:, reduced operating costs and contributed to the growing popularity of radio. A 1479:(or "beam power tube") forms the electron stream from the cathode into multiple 513:

in a vacuum inside an airtight envelope. Most tubes have glass envelopes with a

7371: 7346: 7062: 6843: 6833: 6599: 6402: 5698: 5634: 5392:"Remember when TVs weighed 200 pounds? A look back at TV trends over the years" 3801: 3518: 3319: 3042: 3033:. This is particularly true at microwave frequencies where such devices as the 2867: 2832: 2805: 2695: 2549: 2544: 2390: 2202: 2127: 1833: 1817: 1682: 1523: 1140: 1001: 997: 410: 162: 135: 35: 5538: 5410: 1909:

and aluminum that can reduce emissivity also contribute to long cathode life.

1868: 846:

radio frequency current as the detector component of radio receiver circuits.

7488: 7411: 7406: 7296: 7217: 7187: 7124: 6947: 6863: 6682: 6509: 6477: 5547: 4714: 4664: 4287: 3958: 3911: 3452: 3444: 3437: 3432: 2666: 2495: 1918: 1851: 1837: 1825: 1755: 1173: 978: 943: 914: 872: 839: 746: 726: 694: 693:. The many scientists and inventors who experimented with such tubes include 686: 678: 568: 260: 186: 5992:; Van Valkenburgh, Nooger & Neville Inc.; John F. Rider Publisher; 1955. 5984:, Ziff Publishing, 1943, (reprint 1994 Prompt Publications), pp. 30–83. 4955: 4674:, Radio Constructor (See particularly the section "Glass Base Construction") 3872: 3796: 1840:. Colossus replaced an earlier machine based on relay and switch logic (the 794:

was engaged in development and construction of radio communication systems.

47: 7376: 7270: 7202: 7197: 7005: 6993: 6881: 6848: 6677: 6662: 6229: 5565: 5209:

Vacuum Technology Transactions: Proceedings of the Sixth National Symposium

5083: 3315: 3251: 2871: 2859: 2785: 2758: 2706: 2658: 2374: 2355: 2332: 2000:

is not possible inside most tubes since the anode is surrounded by vacuum.

1893: 1640:" (named due to its shape) was also very small, as was the metal-cased RCA 1527: 1484: 1476: 1467: 1458: 1402: 1364: 1309: 1284: 1241: 1161: 930: 702: 690: 685:

The 19th century saw increasing research with evacuated tubes, such as the

595: 552:

in an evacuated glass envelope. When hot, the filament in a vacuum tube (a

396: 194: 5951: 5266: 4152:

The Thermionic Valve and its Developments in Radiotelegraphy and Telephony

3981: 2985: 2065:

was a modern receiving tube using a very small metal and ceramic package.

367:

by power rating (small-signal, audio power, high-power radio transmitting)

7473: 7381: 7192: 7047: 6789: 6629: 6412: 6374: 3662:

Englishes Around the World: General studies, British Isles, North America

3544: 3486: 3457: 2820: 2790: 2780: 2439: 2378: 2070: 1937: 1873: 1670: 1616: 1436: 1228: 1009: 611: 599: 526: 406: 402:

specialized functions (light or radiation detectors, video imaging tubes)

371: 309:

One classification of thermionic vacuum tubes is by the number of active

297: 237: 111: 107: 6087: 4102:"Robert von Lieben — Patent Nr 179807 Dated November 19, 1906" 2435: 1303:

means the tube has five electrodes. The pentode was invented in 1926 by

153: 7396: 7326: 7316: 7311: 7255: 7119: 7109: 7042: 6916: 6886: 6853: 6828: 6823: 6800: 6672: 6652: 6530: 6392: 6369: 6255: 6157: 6152: 6147: 6028: 3539: 3514: 3174: in this section. Unsourced material may be challenged and removed. 3127: 3116: 3087: 3082:

Tube amplifiers remain commercially viable in three niches where their

3066: 2882: 2699: 2600: 2540: 2468: 2451: 2323: 2315: 2208: 2159: 1997: 1637: 1425: 1280: 1185: 710: 673: 438: 310: 275: 252: 228:. Although some applications had used earlier technologies such as the 205: 52: 39: 6031:. Fleming discovers the thermionic (or oscillation) valve, or 'diode'. 5473:

2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)

1547:

vapor to achieve a lower forward voltage drop than high-vacuum tubes.

965:

plate voltage was high (above about 60 volts). In 1912, de Forest and

493: 281:

Not all electronic circuit valves or electron tubes are vacuum tubes.

266:

Thermionic tubes are still employed in some applications, such as the

141: 7361: 7356: 7336: 7082: 6926: 6921: 6911: 6838: 6718: 6552: 6547: 6472: 6397: 3282: 3270: 3266: 3046: 2973: 2926: 2812: 2764: 2694:

filaments since they operate at much lower temperature. The surge of

2628: 2589: 2382: 2339: 2338:

The "C battery" for bias is a designation having no relation to the "

2314:

Three-battery array powering a vacuum-tube circuit (highlighting the

2299: 2287: 2191: 2163: 2143: 2134:

in operation. Low-pressure gas within tube glows due to current flow.

2005: 1972: 1605: 1539: 1383: 1154: 1149: 938: 843: 590: 585: 510: 470: 442: 361: 326: 318: 271: 267: 217: 123: 119: 115: 84: 31: 7137: 4195:

Radio Engineering for Wireless Communication and Sensor Applications

3895:. London and Glasgow: William Collins, Sons, & Company. p. 3149: 2302:

or the HT (high-tension) supply or battery. These were generally of

1786:(one of the first commercially available electronic computers), and 177:) that would be included in series with the C and B voltage sources. 7341: 7321: 7260: 7104: 7052: 7032: 7010: 6896: 6891: 6779: 6768: 6697: 6467: 6034: 3699:

The Penguin Encyclopedia of Modern Warfare: 1850 to the present day

3554: 3471: 3325: 3034: 2888: 2824: 2620: 2604: 2303: 2183: 2062: 1906: 1885: 1787: 1641: 1621: 1600: 1086:. The Van der Bijl equation defines their relationship as follows: 867: 630: 559: 174: 170: 3330:

All tubes with one or more control grids are controlled by an AC (

2298:

The high voltage applied to the anode (plate) was provided by the

1952:

calculators, and was designated as a general-purpose triode tube.

1857: 1035:

devices, in which the controlling signal applied to the grid is a

7275: 7265: 6964: 6901: 6723: 6708: 6562: 6519: 6167: 3687:. New York: W. W. Norton & Co. Inc. p. 58. Retrieved Oct 2021 2657:

Cathodes in small "receiving" tubes are coated with a mixture of

2637: 2624: 2516: 2488: 2198: 2175: 2057: 2052:

Most modern tubes have glass envelopes, but metal, fused quartz (

1949: 1881: 1812:

Vacuum tubes seen on end in a recreation of the World War II-era

1645: 1608:, in higher-power audio output stages and as transmitting tubes. 1368: 1291: 1210: 1201: 1197: 1039:, and the resulting amplified signal appearing at the anode is a 922: 815: 779: 654: 650: 588:. Since current can only pass in one direction, such a diode (or 554: 530: 480: 338: 334: 88: 5194: 4745:

Colossus: The Secrets of Bletchley Park's Codebreaking Computers

4743:

Copeland, B. Jack (2006). "Chapter 5: Machine against Machine".

4155:. London, UK: The Wireless Press Ltd. p. 115. Retrieved Oct 2021 3367:) can be affected by a small input voltage applied on the grid ( 1888:

alloy to make the heater wire easier to draw. The silicon forms

1824:

Colossus I and its successor Colossus II (Mk2) were designed by

1543:

they do perform electronic functions. High-power rectifiers use

7286: 7250: 7245: 7222: 7037: 6728: 6692: 6657: 6217: 6189: 6162: 6137: 5173:, San Carlos, CA: CPI, EIMAC Div., p. 68. Retrieved 25 Oct 2021 5125:

New York: General Electric Review. p. 174. Retrieved Nov. 2021

4073:

Manual of Wireless Telegraphy for the use of Naval Electricians

3781:"Triode amplifiers in the frequency range 100 Mc/s to 420 Mc/s" 3492: 3300: 3011: 2934: 2916: 2725: 2585: 2573: 2569: 2520: 2484: 2479: 2455: 2151: 2053: 1955:

The tubes developed for Whirlwind were later used in the giant

1932:, also labeled as E180CC. This, according to a memorandom from 1678: 1655: 1352: 918: 908: 875: 862: 849:

While offering no advantage over the electrical sensitivity of

754: 750: 646: 499: 450: 399:

and low-noise audio amplification, rugged or military versions)

322: 158: 80: 6065: 4957:

Technical Manual TT-5 | Transmitting Tubes to 4 KW Plate Input

4559:, New York: McGraw-Hill, pp. 164 - 179. Retrieved 10 June 2021 4091:. London: The Wireless Press, Ltd. p. 74. Retrieved Nov. 2021. 3071: 1733: 1599:

Early tubes used a metal or glass envelope atop an insulating

1363:

have been used for this purpose. The additional grids include

1332:

contains five grids between the cathode and the plate (anode).

7114: 7025: 6784: 6557: 6350: 6212: 6207: 3495:—a solid-state, plug-compatible, replacement for vacuum tubes 3278: 3274: 3133: 2900: 2828: 2645: 2205:; krytrons are heavily controlled at an international level. 2179: 2147: 2108: 2091: 2078: 1775: 1771: 1738: 1568: 1410: 882: 834: 774: 581: 573: 518: 484: 476: 314: 209: 201: 182: 149:, the hot cathodes emitting their distinctive red-orange glow 131: 3697:

Macksey, Kenneth; Woodhouse, William (1991). "Electronics".

3289:

technology, but there were significant production problems.

2228:

is an extremely sensitive detector of light, which uses the

1351:

tube. Various alternatives such as using a combination of a

502:: voltage applied to the grid controls plate (anode) current 385:

by characteristic curves design (e.g., sharp- versus remote-

7057: 6440: 6386: 6287: 6240: 6178: 5820:, Merlin Blencowe, Wem Publishing (2012), 978-0-9561545-2-1 5084:

National Valve Museum: audio double triodes ECC81, 2, and 3

4783:"A lost interview with ENIAC co-inventor J. Presper Eckert" 2155: 2013: 1929: 1913: 1898: 1892:

at the interface between the nickel sleeve and the cathode

1421: 1406: 1031:

The triode and its derivatives (tetrodes and pentodes) are

1021: 921:. By placing an additional electrode between the filament ( 5656:"The cool sound of tubes—vacuum tube musical applications" 5511: 5470: 5189:, Indianapolis, Indiana, USA: Howard W. Sams, p. 23, 4846: 4834: 3756:

Electronics: A General Introduction for the Non-Specialist

2036: 1677:'s mercury displacement pump, which left behind a partial 1324: 1206: 1050:

For vacuum tubes, transconductance or mutual conductance (

6040: 4962: 4822: 4639:, New York: RCA Institutes Technical Press, pp. 101 - 108 2505: 2385:(which may themselves be vacuum tubes), and large filter 1941: 1690:

oxide-coated filaments in the mid-1920s reduced filament

1583: 1487:

region between the anode and screen grid to return anode

890: 842:, the oscillation valve was developed for the purpose of 357: 353: 6035:"Tubes Vs. Transistors: Is There an Audible Difference?" 5514:"A simplified description of X-ray free-electron lasers" 4310:"The Shielded Plate Valve as a High-Frequency Amplifier" 2970:

in which the discrete channels substitute for focusing.

2240:

use photomultiplier tube arrays to detect low-intensity

2044: 1463: 745:

Amplification by vacuum tube became practical only with

734:

applied the rectifying property of the Edison effect to

5441: 5015:

The maximum anode dissipation rating is 2500 kilowatts.

2986:

Industrial, commercial, and military niche applications

2644:

achieved 163,000 hours (18.6 years) of service from an

2100:

Radio Electronics Television Manufacturers' Association

2016:

is among the largest commercial tubes available today.

1319: 5588:

Physical Review Special Topics: Accelerators and Beams

4605:, Schenectady, NY: Tube Division, General Electric Co. 4473:

Handbook for Sound Engineers: The New Audio Cyclopedia

2950:(itself not an actual vacuum tube). Historically, the 2899:, used to generate high-power coherent light and even 5512:

Margaritondo, G.; Rebernik Ribic, P. (1 March 2011).

5027:

The Oxford Companion to the History of Modern Science

3785:

Journal of the British Institution of Radio Engineers

1092: 259:(CRT) remained the basis for television monitors and 4570:"500-Mc. Transmitting Tetrode Design Considerations" 4264:. Washington D. C.: USGPO. p. 42. Retrieved Oct 2021 3467: 2990:

Although vacuum tubes have been largely replaced by

1673:

required to evacuate the enclosures. de Forest used

1008:

Pliotrons were closely followed by the French type '

806:. One of Marconi's needs was for improvement of the 5818:

Designing Tube Preamps for Guitar and Bass, 2nd ed.

5101:

Certified by BBC central valve stores, Motspur Park

4917:

Memorandum M-2135: Some notes on current tube types

4389:"Philips Historical Products: Philips Vacuum Tubes" 3404:

V-I curve (Voltage across filaments, plate current)

3265:Such integrated microtubes may find application in 2980: 5662:. Vol. 35, no. 8. IEEE. pp. 24–35. 4954: 4948: 4258:Departments of the Army and the Air Force (1952). 4223: 3800: 1125: 4342:British Radio Valves The Classic Years: 1926-1946 3448:—Device for amplifying feeble electrical currents 2623:filaments containing a small trace (1% to 2%) of 2572:, which are usually metals that oxidize quickly, 2535:A vacuum tube needs an extremely high vacuum (or 614:invented the indirectly heated tube around 1913. 126:, however, achieve electron emission through the 7525:Telecommunications-related introductions in 1904 7486: 4369:Introduction to Thermionic Valves (Vacuum Tubes) 4064: 3696: 3489:—close to manufacturer's stated parameter values 3326:Voltage - Current characteristics of vacuum tube 3308: 2870:", a specialized sort of CRT used in place of a 270:used in microwave ovens, certain high-frequency 5770:"Vacuum tubes could be the future of computing" 5332:Analogue Oscilloscope: cathode ray oscilloscope 4892:AN/FSQ-7: The Computer that Shaped the Cold War 3925: 3923: 3921: 1741:computer used 17,468 vacuum tubes and consumed 1587:Subminiature CV4501 tube (SQ version of EF72), 1495:Manufacturer's data sheets often use the terms 753:" tube, a crude form of what was to become the 27:Device that controls current between electrodes 6046:O'Neill's Electronic museum—vacuum tube museum 4261:Basic Theory and Application of Electron Tubes 3417: 3376:), for any given voltage on the plate(anode) ( 2393:voltages from the alternating current source. 1967: 1912:The first such "computer tube" was Sylvania's 1722: 606:(AM) radio signals and for similar functions. 382:(including "bright-emitter" or "dull-emitter") 378:type (indirectly heated, directly heated) and 161:vacuum tube and the polarities of the typical 7153: 6103: 6062:—Data manual for tubes used in North America. 5970:, Vestal Press, New York, 1982, pp. 3–9. 5879:Station X: The Codebreakers of Bletchley Park 5424:Diagram of continuum and characteristic lines 4865: 4863: 4861: 4654:. Harrison, NJ: Tube Division, RCA. pp. 1,2,6 4190: 1698: 1442:. The similar 7360 was popular as a balanced 738:of radio signals, as an improvement over the 5581:"Review of x-ray free-electron laser theory" 5448:Principles of Modern Radar: Basic Principles 5435: 5001:"MULTI-PHASE COOLED POWER TETRODE 4CM2500KG" 4988:GS-9B Oscillator Ultra-High Frequency Triode 4107:. Kaiserliches Patentamt. 19 November 1906. 3918: 3407:Plate current, plate voltage characteristics 2799: 2115:A system widely used in Europe known as the 1928:Another commonly used computer tube was the 1848:on such a large scale for a single machine. 1656:Improvements in construction and performance 395:specialized parameters (long life, very low 5939: 5442:Richards, Mark A.; William A. Holm (2010). 5227: 5225: 4781:Randall, Alexander 5th (14 February 2006). 4738: 4736: 4734: 4732: 4709:. Vol. 6, no. 3. pp. 52–55. 4477:(1st ed.). Howard W. Sams Co. p. 4061:. U. S. patent 803,684. Retrieved Nov 2021. 3850: 2523:in opened tube; silvery deposit from getter 1985:types, red heat indicates severe overload. 1567:-diameter base, while the smaller, a 9-pin 941:. In 1908, de Forest was granted a patent ( 7160: 7146: 6110: 6096: 5975:History of the British Radio Valve to 1940 5857:Colossus: Bletchley Park's Greatest Secret 5345: 5154:Principles and Practice of Radio Servicing 4941: 4869: 4858: 4687:, 4th ed. Newnes-Butterworth, London 1976 4088:Direction and Position Finding by Wireless 3134:Vacuum tubes using field electron emitters 2878:(VFD) is also a sort of cathode-ray tube. 668: 75:(North America) is a device that controls 6117: 5607: 5555: 5537: 5161: 5122:Production and Measurement of High Vacuum 5046: 4885: 4883: 4881: 4704: 4441:"Mu, Gm and Rp and how Tubes are matched" 4331:. New York: McGraw-Hill. pp. 3-34 - 3-38. 4273: 3944: 3354:This relationship is shown with a set of 3234:Learn how and when to remove this message 2619:Large transmitting tubes have carbonized 2219: 749:'s 1907 invention of the three-terminal " 313:. A device with two active elements is a 5676: 5621: 5619: 5578: 5361: 5222: 4922:(Report). MIT. p. 3. Archived from 4742: 4729: 4590:, San Carlos, CA: CPI, EIMAC Div., p. 28 4191:Räisänen, Antti V.; Lehto, Arto (2003). 4166:"AT&T Labs Research | AT&T" 3915:"Electrical Indicator", Issue date: 1884 3521:sometimes misidentified as a vacuum tube 3299: 3115:was the dominant display technology for 3070: 2784: 2716: 2681: 2526: 2515: 2434: 2309: 2126: 2122: 2043: 2035: 1971: 1867: 1807: 1732: 1659: 1615: 1582: 1554: 1462: 1323: 1246: 1205: 1191: 1126:{\displaystyle g_{m}={\mu \over R_{p}}} 949: 889: 881: 866: 778: 672: 296: 165:operating potentials. Not shown are the 152: 140: 122:. Non-thermionic types such as a vacuum 46: 5722:"Flat Panels Drive Old TVs From Market" 5653: 5052: 4872:Component failure analysis in computers 4780: 4747:. Oxford University Press. p. 72. 4633:"New Developments in Audio Power Tubes" 4334: 4226:"General Electric Research Lab History" 4134:"Birth of the Electron Tube Amplifier". 3885: 3724: 3722: 3615:. Elektor Electronics. 1 January 2011. 2906: 2322:Early sets used a grid bias battery or 1347:, combined in the function of a single 541:The earliest vacuum tubes evolved from 14: 7487: 5854: 5807:from the original on 17 November 2015. 5013:from the original on 11 October 2016. 4889: 4878: 4852: 4840: 4811: 4465: 4319: 3778: 1611: 1043:. Compare this to the behavior of the 509:A vacuum tube consists of two or more 157:Illustration representing a primitive 7167: 7141: 6091: 6022:The invention of the thermionic valve 5873: 5616: 5572: 5389: 5250:"Getter Materials for Electron Tubes" 5239:, pp. 519 - 525 Retrieved 25 Oct 2021 5235:New Jersey: Electron Tube Div., RCA. 5182: 5138:New Jersey: Electron Tube Div., RCA. 4914: 4828: 4685:Electronics Engineer's Reference Book 4413: 3840:from the original on 3 December 2016. 3753: 3728: 3574: 3269:devices including mobile phones, for 2614: 1858:Whirlwind and "special-quality" tubes 6542:Three-dimensional integrated circuit 5767: 5719: 5666:from the original on 4 January 2012. 5186:Getting the Most out of Vacuum Tubes 5170:Care and Feeding of Power Grid Tubes 4805: 4707:IEEE Industrial Electronics Magazine 4587:Care and Feeding of Power Grid Tubes 4494:Amplification factor or voltage gain 4438: 4395:from the original on 6 November 2013 3819: 3719: 3304:Typical triode plate characteristics 3172:adding citations to reliable sources 3143: 2839: 2295:for the heaters had been developed. 2255: 1320:Multifunction and multisection tubes 6323:Programmable unijunction transistor 5977:, MMA International, 1982, pp 9–13. 5798: 5450:. SciTech Pub., 2010. p. 360. 5277:from the original on 20 August 2013 4870:Rich, E. S.; Taylor, N. H. (1950). 4172:from the original on 5 October 2013 3990:from the original on 18 August 2012 3575:Reich, Herbert J. (13 April 2013). 3140:Nanoscale vacuum-channel transistor 3106: 2381:with several windings, one or more 1872:Circuitry from core memory unit of 1514: 1452: 720:was originally reported in 1873 by 637:often operate their anodes (called 24: 6224:Multi-gate field-effect transistor 5968:70 Years of Radio Tubes and Valves 5897: 5780:from the original on 25 March 2013 5073:from the original on 22 June 2013. 4599:GE Electronic Tubes, (March 1955) 3664:, John Benjamins Publishing, 1997 3601:from the original on 2 April 2017. 3295: 3023:industrial radio frequency heating 2652: 2040:Metal-cased tubes with octal bases 1550: 562:into the vacuum, a process called 321:. Devices with three elements are 292: 25: 7541: 6202:Insulated-gate bipolar transistor 6009: 5351:Thomson Consumer Electronics Inc. 5256:pp. 80 - 86 Retrieved 25 Oct 2021 5110:Mazda Data Booklet 1968 Page 112. 4812:Jacobs, Donald H. (14 May 1952). 4614:J. F. Dreyer, Jr., (April 1936). 4568:Winfield G. Wagener, (May 1948). 3983:United States Early Radio History 3979: 2862:(based on internal computers and 2751: 2744:failure of monochrome television 2326:which was connected to provide a 1144:input voltage around that point. 6446:Heterostructure barrier varactor 6173:Chemical field-effect transistor 5834: 5823: 5811: 5792: 5761: 5518:Journal of Synchrotron Radiation 5248:Espe, Knoll, Wilder (Oct. 1950) 4622:, Vol. 9, No. 4, pp. 18 - 21, 35 4575:, p. 612. Retrieved 10 June 2021 4114:from the original on 28 May 2008 3857:. Tokyo: Ohmsha. pp. 7–25. 3681:Hoddeson L., Riordan M. (1997). 3510:Mullard–Philips tube designation 3470: 3256:large-area field electron source 3148: 2981:Vacuum tubes in the 21st century 2676: 2117:Mullard–Philips tube designation 2031: 663:junction field-effect transistor 492: 469: 214:sound recording and reproduction 34:. For the transport system, see 6494:Mixed-signal integrated circuit 5847: 5736: 5713: 5670: 5647: 5628: 5505: 5464: 5417: 5402: 5383: 5339: 5325: 5313: 5301: 5289: 5259: 5242: 5201: 5176: 5145: 5128: 5113: 5104: 5095: 5077: 5032: 5020: 4993: 4981: 4908: 4774: 4698: 4677: 4657: 4642: 4625: 4608: 4593: 4578: 4562: 4547: 4533: 4519: 4505: 4459: 4432: 4407: 4381: 4362: 4347: 4325:Landee, Davis, Albrecht (1957) 4302: 4267: 4252: 4243: 4217: 4184: 4158: 4143: 4126: 4094: 4079: 4049: 4033: 4020: 3994: 3973: 3938: 3903: 3879: 3844: 3813: 3159:needs additional citations for 2557:10 Torr; 130 μPa; 1.3 1790:, also available commercially. 1644:from 1959, about the size of a 1168:without requiring replacement. 333:. Additional electrodes create 243:In the 1940s, the invention of 6071:Characteristics and datasheets 6066:Vacuum tube data sheet locator 5989:Basic Electronics: Volumes 1–5 5635:Y Butt, The Space Review, 2011 5579:Huang, Z.; Kim, K. J. (2007). 5444:"Power Sources and Amplifiers" 5158:pp. 252. Retrieved 25 Oct 2021 5142:, p. 34. Retrieved 25 Oct 2021 4359:. New York: McGraw-Hill. p. 88 4344:, Reading, UK: Speedwell, p. 3 4328:Electronic Designers' Handbook 4132:F. B. Llewellyn. (Mar. 1957). 3772: 3747: 3690: 3675: 3654: 3629: 3605: 3568: 3397:) as the input signal varies. 2430: 1184:and led to the success of the 757:. Being essentially the first 709:. With the exception of early 460: 263:until the early 21st century. 181:The simplest vacuum tube, the 13: 1: 5940:Spangenberg, Karl R. (1948). 5923:Radiotron Designer's Handbook 5720:Wong, May (22 October 2006). 5609:10.1103/PhysRevSTAB.10.034801 4353:Happell, Hesselberth (1953). 3932:Memories of a Scientific Life 3637:"RCA Electron Tube 6BN6/6KS6" 3561: 3505:List of vacuum-tube computers 3456:—de Forest's three electrode 3356:Plate Characteristics curves, 3309:Space charge of a vacuum tube 3093:Many guitarists prefer using 2940:Single-photon avalanche diode 2665:, sometimes with addition of 2238:liquid scintillation counters 2188:silicon-controlled rectifiers 2162:at predictable voltages. The 1729:List of vacuum-tube computers 1287:oscillator many years later. 6525:Silicon controlled rectifier 6387:Organic light-emitting diode 6277:Diffused junction transistor 5914:, 2nd ed. McGraw-Hill, 1951. 5910:Millman, J. & Seely, S. 5905:Fundamentals of Vacuum Tubes 5414:. Priority date May 9, 1913. 5369:"How Computer Monitors Work" 4950:"Construction and Materials" 4616:"The Beam Power Output Tube" 4553:Donovan P. Geppert, (1951). 4443:. Välljud AB. Archived from 4046:p. 411. Retrieved Nov. 2021. 3754:Olsen, George Henry (2013). 3578:Principles of Electron Tubes 2864:analog-to-digital converters 2260: 1179:Eventually the technique of 798:appointed English physicist 289:, usually without a heater. 247:made it possible to produce 7: 7240: 6329:Static induction transistor 6266:Bipolar junction transistor 6218:MOS field-effect transistor 6190:Fin field-effect transistor 5481:10.1109/PLASMA.2013.6635226 5267:"The Klystron & Cactus" 4915:Frost, H. B. (4 May 1953). 4224:Edison Tech Center (2015). 4138:Radio & Television News 3584:. Literary Licensing, LLC. 3463: 3418:Size of electrostatic field 3101: 3060: 2349: 2220:§ Electron multipliers 1992:Heat escapes the device by 1968:Heat generation and cooling 1948:, primarily for use in the 1921:on the heater element, and 1797: 1723:Use in electronic computers 1685:in 1915 and improvement by 1483:to produce a low potential 1045:bipolar junction transistor 415:vacuum fluorescent displays 344:Other classifications are: 287:electric discharge in gases 189:), was invented in 1904 by 10: 7546: 6536:Static induction thyristor 6051:Vacuum tubes for beginners 5999:. UK reprint of the above. 5859:. London: Atlantic Books. 5429:February 23, 2008, at the 5207:C. Robert Meissner (ed.), 5059:. IOS Press. p. 133. 4763:, accessed 7 August 2024. 4651:6L6, 6L6-G Beam Power Tube 4631:R. S. Burnap (July 1936). 4602:6V6GT - 5V6GT Beam Pentode 4308:Beatty, R. T. (Oct. 1927) 3733:(4th ed.). Elsevier. 3425: 3137: 3064: 2910: 2876:vacuum fluorescent display 2843: 2778: 2774: 2353: 2264: 2217: 2197:A specialized tube is the 1861: 1801: 1726: 1699:Indirectly heated cathodes 1481:partially collimated beams 1456: 1382:. An early example is the 1195: 1002:high-vacuum diffusion pump 860: 856: 772: 572:. A second electrode, the 483:flow towards the positive 38:. For blood sampling, see 29: 7461: 7420: 7283:(Hexode, Heptode, Octode) 7231: 7175: 7073: 6973: 6940: 6872: 6809: 6737: 6705:(Hexode, Heptode, Octode) 6643: 6575: 6457:Hybrid integrated circuit 6421: 6349: 6300:Light-emitting transistor 6254: 6136: 6125: 6041:The cathode-ray tube site 5997:Radio Designer's Handbook 5539:10.1107/S090904951004896X 5056:History of electron tubes 4573:Proceedings of the I.R.E. 3892:Magnetism and Electricity 3854:History of electron tubes 3851:Okamura, S., ed. (1994). 3758:. Springer. p. 391. 3535:Russian tube designations 2946:as an alternative to the 2800:Other vacuum tube devices 2599:and camera tubes such as 2511: 1681:. The development of the 1391:British Valve Association 1367:(at a low potential) and 1337:Superheterodyne receivers 959:Science History Institute 902:filed for a patent for a 768: 659:voltage-controlled device 479:: electrons from the hot 435:electron beam lithography 114:functions such as signal 7302:Backward-wave oscillator 6752:Backward-wave oscillator 6462:Light emitting capacitor 6318:Point-contact transistor 6288:Junction Gate FET (JFET) 5699:10.1088/1361-6552/aa57b7 4815:The JAINCOMP-B1 Computer 4715:10.1109/MIE.2012.2207830 4670:23 December 2015 at the 4288:10.1109/MIE.2012.2193274 4199:. Artech House. p. 3959:10.1109/MIE.2012.2182822 3501:—a list of type numbers. 3021:in applications such as 2952:image orthicon TV camera 2178:as control switches for 2084: 1221:invented the tetrode or 1005:invalidated the patent. 955:General Electric Company 543:incandescent light bulbs 6763:Crossed-field amplifier 6282:Field-effect transistor 6076:13 January 2012 at the 5982:Saga of the Vacuum Tube 5252:New York: McGraw-Hill. 5136:"Oxide-Coated Emitters" 4418:. Newnes. p. 391. 4356:Engineering Electronics 4149:Fleming, J. A. (1919). 4070:Robison, S. S. (1911). 4055:Fleming, J. A. (1905). 3929:Fleming, J. A. (1934). 3797:10.1049/jbire.1951.0074 3701:. Viking. p. 110. 2454:of free gas molecules. 2140:voltage-regulator tubes 1147:This concept is called 1016:down to 10 nPa (8 669:History and development 397:microphonic sensitivity 7176:Theoretical principles 6932:Voltage-regulator tube 6499:MOS integrated circuit 6364:Constant-current diode 6340:Unijunction transistor 5830:indiastudychannel.com/ 5089:7 January 2011 at the 5053:Okamura, Sōgo (1994). 4890:Ulmann, Bernd (2014). 4665:The Story of the Valve 4414:Baker, Bonnie (2008). 4340:K. R. Thrower, (2009) 4136:New York: Ziff-Davis. 3779:Rogers, D. C. (1951). 3729:Jones, Morgan (2012). 3525:RETMA tube designation 3305: 3287:field emission display 3079: 3031:broadcast transmitters 2793: 2532: 2524: 2443: 2389:provided the required 2319: 2135: 2132:Voltage-regulator tube 2049: 2041: 1981: 1876: 1821: 1746: 1666: 1632: 1596: 1580: 1536:voltage-regulator tube 1472: 1399:automatic gain control 1333: 1305:Bernard D. H. Tellegen 1252: 1214: 1136:approximately linear. 1127: 961: 895: 887: 879: 871:The first triode, the 787: 763:public address systems 707:Johann Wilhelm Hittorf 682: 405:tubes used to display 306: 178: 150: 145:Operating tubes in an 56: 7510:Electrical components 7332:Inductive output tube 7001:Electrolytic detector 6774:Inductive output tube 6590:Low-dropout regulator 6505:Organic semiconductor 6436:Printed circuit board 6272:Darlington transistor 6119:Electronic components 5931:Receiving Tube Manual 5855:Gannon, Paul (2006). 5640:22 April 2012 at the 5411:U.S. patent 1,203,495 5335:electronics-notes.com 5319:Tomer, R. B. (1960). 5307:Tomer, R. B. (1960). 5295:Tomer, R. B. (1960). 5231:Thomas, C. H. (1962) 5183:Tomer, R. B. (1960), 5134:Hadley, C. P. (1962) 4990:Archived 25 Feb. 2021 4894:. Walter de Gruyter. 4767:23 March 2012 at the 4759:Extract available at 4695:pages 7–2 through 7-6 4276:IEEE Ind. Electron. M 3947:IEEE Ind. Electron. M 3303: 3277:transmission, and in 3074: 3027:particle accelerators 2999:electromagnetic pulse 2788: 2717:Degenerative failures 2682:Catastrophic failures 2530: 2519: 2438: 2399:AC/DC receiver design 2367:batteryless receivers 2313: 2267:Battery (vacuum tube) 2130: 2123:Special-purpose tubes 2047: 2039: 1975: 1871: 1811: 1758:, who later designed 1736: 1692:operating temperature 1663: 1619: 1586: 1558: 1466: 1327: 1268:and is an example of 1250: 1209: 1192:Tetrodes and pentodes 1172:input), known as the 1128: 994:Schenectady, New York 992:research laboratory ( 953: 893: 885: 870: 782: 676: 300: 245:semiconductor devices 230:spark gap transmitter 156: 147:audio power amplifier 144: 87:to which an electric 50: 7474:List of tube sockets 7469:List of vacuum tubes 7307:Beam deflection tube 6819:Beam deflection tube 6488:Metal-oxide varistor 6381:Light-emitting diode 6235:Thin-film transistor 6196:Floating-gate MOSFET 6003:"Vacuum Tube Design" 5903:Eastman, Austin V., 5799:Anthony, Sebastian. 5654:Barbour, E. (1998). 5237:Electron Tube Design 5151:Hicks, H. J. (1943) 5140:Electron Tube Design 4855:, pp. 255, 284. 4843:, pp. 245, 246. 4831:, pp. 148, 149. 4556:Basic Electron Tubes 4230:edisontechcenter.org 4039:Editors (Sept 1954) 3805:on 27 February 2020. 3530:RMA tube designation 3499:List of vacuum tubes 3168:improve this article 3075:70-watt tube-hybrid 2913:Photomultiplier tube 2907:Electron multipliers 2897:Free-electron lasers 2817:traveling-wave tubes 2811:Some tubes, such as 2442:manufactured in 1930 2230:photoelectric effect 2226:photomultiplier tube 1994:black-body radiation 1940:, was developed for 1890:barium orthosilicate 1864:Whirlwind (computer) 1751:mean time to failure 1401:rectifier and audio 1397:used as a detector, 1308:applications is the 1090: 800:John Ambrose Fleming 759:electronic amplifier 732:John Ambrose Fleming 523:borosilicate glasses 487:, but not vice versa 348:by frequency range ( 234:mechanical computers 191:John Ambrose Fleming 128:photoelectric effect 106:of electrons from a 94:The type known as a 89:potential difference 71:(British usage), or 7392:Traveling-wave tube 7183:Thermionic emission 6795:Traveling-wave tube 6595:Switching regulator 6431:Printed electronics 6408:Step recovery diode 6185:Depletion-load NMOS 6027:16 October 2012 at 6018:—FAQ from rec.audio 6016:The Vacuum Tube FAQ 5907:, McGraw-Hill, 1949 5881:. Channel 4 Books. 5691:2017PhyEd..52b5010K 5600:2007PhRvS..10c4801H 5530:2011JSynR..18..101M 5119:Dushman, S. (1922) 4663:C H Gardner (1965) 4439:Modjeski, Roger A. 4374:28 May 2007 at the 4041:"World of Wireless" 3912:U.S. patent 307,031 3820:Bray, John (2002). 3453:U.S. patent 879,532 3445:U.S. patent 841,387 3433:U.S. patent 803,684 3332:Alternating Current 3260:field emitter array 3039:traveling-wave tube 2856:flat panel displays 2642:Huntsville, Alabama 1830:General Post Office 1768:electronic switches 1612:Sub-miniature tubes 1395:double diode triode 1349:pentagrid converter 1330:pentagrid converter 1316:, discussed below. 1277:dynatron oscillator 1270:negative resistance 944:U.S. patent 879,532 718:thermionic emission 604:amplitude modulated 564:thermionic emission 535:phenolic insulation 515:glass-to-metal seal 455:thermionic emission 431:electron microscopy 317:, usually used for 104:thermionic emission 7520:Glass applications 7515:English inventions 7505:1904 in technology 7100:Crystal oscillator 6960:Variable capacitor 6635:Switched capacitor 6577:Voltage regulators 6451:Integrated circuit 6335:Tetrode transistor 6313:Pentode transistor 6306:Organic LET (OLET) 6293:Organic FET (OFET) 6060:NJ7P Tube Database 5749:. Veritas et Visus 5724:. AP via USA Today 5390:Katzmaier, David. 5198:Retrieved Oct 2021 4965:. 1962. p. 10 4761:the book's website 4683:L.W. Turner (ed.) 4378:, Colin J. Seymour 3887:Guthrie, Frederick 3478:Electronics portal 3306: 3248:integrated circuit 3080: 3007:geomagnetic storms 3003:nuclear explosions 2964:microchannel plate 2948:Geiger–Müller tube 2944:ionizing radiation 2931:secondary emission 2794: 2615:Transmitting tubes 2533: 2525: 2444: 2363:battery eliminator 2320: 2246:ionizing radiation 2234:secondary emission 2136: 2050: 2042: 1982: 1877: 1846:working in concert 1822: 1747: 1667: 1633: 1597: 1581: 1501:beam power pentode 1489:secondary emission 1473: 1334: 1257:secondary emission 1253: 1219:Walter H. Schottky 1215: 1174:Miller capacitance 1123: 962: 896: 888: 880: 878:, invented in 1906 788: 683: 681:experimental bulbs 584:, and is used for 307: 179: 151: 91:has been applied. 57: 7482: 7481: 7421:Numbering systems 7402:Video camera tube 7387:Talaria projector 7169:Thermionic valves 7135: 7134: 7095:Ceramic resonator 6907:Mercury-arc valve 6859:Video camera tube 6811:Cathode-ray tubes 6571: 6570: 6179:Complementary MOS 5888:978-0-7522-2189-2 5744:"The Standard TV" 5679:Physics Education 5490:978-1-4673-5171-3 5211:, Elsevier, 2016, 5066:978-90-5199-145-1 4754:978-0-19-957814-6 4488:978-0-672-21983-2 4425:978-0-7506-8627-3 4314:Wireless Engineer 4085:Keen, R. (1922). 3909:Thomas A. Edison 3708:978-0-670-82698-8 3254:in the form of a 3244: 3243: 3236: 3218: 3121:computer monitors 3019:radio frequencies 2968:image intensifier 2840:Cathode-ray tubes 2789:Universal vacuum 2746:cathode-ray tubes 2597:cathode-ray tubes 2581:induction heating 2561:10 mbar; 1.3 2461:incandescent lamp 2403:All American Five 2256:Powering the tube 1838:Lorenz encryption 1828:and built by the 1814:Colossus computer 1804:Colossus computer 1706:power transformer 1675:Heinrich Geissler 1595:(excluding leads) 1415:guitar amplifiers 1380:multisection tube 1373:All American Five 1121: 973:Finnish inventor 957:Pliotron, at the 900:Robert von Lieben 851:crystal detectors 823:oscillation valve 812:magnetic detector 796:Guglielmo Marconi 740:magnetic detector 722:Frederick Guthrie 620:quiescent current 427:cathode-ray tubes 411:"magic eye" tubes 389:in some pentodes) 305:with vacuum tubes 226:digital computers 18:Thermionic valves 16:(Redirected from 7537: 7292:Cathode-ray tube 7162: 7155: 7148: 7139: 7138: 6989:electrical power 6874:Gas-filled tubes 6758:Cavity magnetron 6585:Linear regulator 6134: 6133: 6112: 6105: 6098: 6089: 6088: 6083:Tuning eye tubes 6055:Japanese Version 5995:Wireless World. 5973:Thrower, Keith, 5963: 5892: 5870: 5841: 5838: 5832: 5827: 5821: 5815: 5809: 5808: 5796: 5790: 5789: 5787: 5785: 5768:Ackerman, Evan. 5765: 5759: 5758: 5756: 5754: 5748: 5740: 5734: 5733: 5731: 5729: 5717: 5711: 5710: 5674: 5668: 5667: 5651: 5645: 5632: 5626: 5623: 5614: 5613: 5611: 5585: 5576: 5570: 5569: 5559: 5541: 5509: 5503: 5502: 5468: 5462: 5461: 5439: 5433: 5421: 5415: 5413: 5406: 5400: 5399: 5387: 5381: 5380: 5378: 5376: 5365: 5359: 5358: 5357: 5353: 5343: 5337: 5329: 5323: 5317: 5311: 5305: 5299: 5293: 5287: 5286: 5284: 5282: 5263: 5257: 5246: 5240: 5229: 5220: 5205: 5199: 5197: 5180: 5174: 5165: 5159: 5149: 5143: 5132: 5126: 5117: 5111: 5108: 5102: 5099: 5093: 5081: 5075: 5074: 5050: 5044: 5036: 5030: 5024: 5018: 5017: 5012: 5005: 4997: 4991: 4985: 4979: 4978: 4975:Internet Archive 4972: 4970: 4960: 4952: 4945: 4939: 4938: 4936: 4934: 4929:on 28 March 2021 4928: 4921: 4912: 4906: 4905: 4887: 4876: 4875: 4867: 4856: 4850: 4844: 4838: 4832: 4826: 4820: 4819: 4809: 4803: 4802: 4800: 4798: 4789:. Archived from 4778: 4772: 4758: 4740: 4727: 4726: 4702: 4696: 4681: 4675: 4661: 4655: 4646: 4640: 4629: 4623: 4612: 4606: 4597: 4591: 4582: 4576: 4566: 4560: 4551: 4545: 4537: 4531: 4523: 4517: 4509: 4503: 4502: 4476: 4463: 4457: 4456: 4454: 4452: 4447:on 21 March 2012 4436: 4430: 4429: 4411: 4405: 4404: 4402: 4400: 4385: 4379: 4366: 4360: 4351: 4345: 4338: 4332: 4323: 4317: 4306: 4300: 4299: 4271: 4265: 4256: 4250: 4247: 4241: 4240: 4238: 4236: 4221: 4215: 4214: 4198: 4188: 4182: 4181: 4179: 4177: 4162: 4156: 4147: 4141: 4130: 4124: 4123: 4121: 4119: 4113: 4106: 4098: 4092: 4083: 4077: 4068: 4062: 4053: 4047: 4037: 4031: 4024: 4018: 4017: 4015: 4013: 4004:. Archived from 3998: 3992: 3991: 3977: 3971: 3970: 3942: 3936: 3927: 3916: 3914: 3907: 3901: 3900: 3883: 3877: 3876: 3848: 3842: 3841: 3817: 3811: 3806: 3804: 3799:. Archived from 3776: 3770: 3769: 3751: 3745: 3744: 3731:Valve Amplifiers 3726: 3717: 3716: 3694: 3688: 3679: 3673: 3658: 3652: 3651: 3649: 3647: 3633: 3627: 3626: 3609: 3603: 3602: 3600: 3583: 3572: 3480: 3475: 3474: 3455: 3447: 3435: 3396: 3384: 3375: 3366: 3239: 3232: 3228: 3225: 3219: 3217: 3176: 3152: 3144: 3113:cathode-ray tube 3107:Cathode-ray tube 3095:valve amplifiers 2852:cathode-ray tube 2846:Cathode-ray tube 2768:better results. 2738:digital circuits 2634:tungsten carbide 2564: 2560: 2556: 2410:voltage doubling 2365:, and, in 1925, 2142:contain various 1979: 1962:submarine cables 1946:General Electric 1938:Project Whirwind 1744: 1631: 1627: 1594: 1590: 1578: 1574: 1566: 1562: 1520:Gas-filled tubes 1515:Gas-filled tubes 1453:Beam power tubes 1341:local oscillator 1223:screen grid tube 1132: 1130: 1129: 1124: 1122: 1120: 1119: 1107: 1102: 1101: 1085: 1076: 1067: 1058: 1033:transconductance 1027: 1019: 990:General Electric 967:John Stone Stone 946: 904:cathode-ray tube 496: 473: 447:photomultipliers 303:signal generator 283:Gas-filled tubes 257:cathode-ray tube 216:, long-distance 110:for fundamental 100:thermionic valve 77:electric current 21: 7545: 7544: 7540: 7539: 7538: 7536: 7535: 7534: 7500:1904 in science 7485: 7484: 7483: 7478: 7457: 7443:Mullard–Philips 7416: 7367:Photomultiplier 7227: 7208:Suppressor grid 7171: 7166: 7136: 7131: 7069: 6984:audio and video 6969: 6936: 6868: 6805: 6733: 6714:Photomultiplier 6639: 6567: 6515:Quantum circuit 6423: 6417: 6359:Avalanche diode 6345: 6257: 6250: 6139: 6128: 6121: 6116: 6078:Wayback Machine 6012: 5980:Tyne, Gerald, 5946:. McGraw-Hill. 5900: 5898:Further reading 5895: 5889: 5867: 5850: 5845: 5844: 5839: 5835: 5828: 5824: 5816: 5812: 5803:. ExtremeTech. 5797: 5793: 5783: 5781: 5766: 5762: 5752: 5750: 5746: 5742: 5741: 5737: 5727: 5725: 5718: 5714: 5675: 5671: 5652: 5648: 5642:Wayback Machine 5633: 5629: 5624: 5617: 5583: 5577: 5573: 5510: 5506: 5491: 5469: 5465: 5458: 5440: 5436: 5431:Wayback Machine 5422: 5418: 5409: 5407: 5403: 5388: 5384: 5374: 5372: 5367: 5366: 5362: 5355: 5344: 5340: 5330: 5326: 5318: 5314: 5306: 5302: 5294: 5290: 5280: 5278: 5265: 5264: 5260: 5247: 5243: 5230: 5223: 5206: 5202: 5181: 5177: 5167:Staff, (2003). 5166: 5162: 5150: 5146: 5133: 5129: 5118: 5114: 5109: 5105: 5100: 5096: 5091:Wayback Machine 5082: 5078: 5067: 5051: 5047: 5042:radiomuseum.org 5037: 5033: 5025: 5021: 5010: 5003: 4999: 4998: 4994: 4986: 4982: 4968: 4966: 4947: 4946: 4942: 4932: 4930: 4926: 4919: 4913: 4909: 4902: 4888: 4879: 4868: 4859: 4851: 4847: 4839: 4835: 4827: 4823: 4810: 4806: 4796: 4794: 4793:on 2 April 2009 4779: 4775: 4769:Wayback Machine 4755: 4741: 4730: 4703: 4699: 4682: 4678: 4672:Wayback Machine 4662: 4658: 4647: 4643: 4630: 4626: 4613: 4609: 4598: 4594: 4584:Staff, (2003). 4583: 4579: 4567: 4563: 4552: 4548: 4543:radiomuseum.org 4538: 4534: 4529:radiomuseum.org 4524: 4520: 4515:radiomuseum.org 4510: 4506: 4499: 4489: 4464: 4460: 4450: 4448: 4437: 4433: 4426: 4416:Analog circuits 4412: 4408: 4398: 4396: 4387: 4386: 4382: 4376:Wayback Machine 4367: 4363: 4352: 4348: 4339: 4335: 4324: 4320: 4307: 4303: 4272: 4268: 4257: 4253: 4248: 4244: 4234: 4232: 4222: 4218: 4211: 4189: 4185: 4175: 4173: 4164: 4163: 4159: 4148: 4144: 4131: 4127: 4117: 4115: 4111: 4104: 4100: 4099: 4095: 4084: 4080: 4069: 4065: 4054: 4050: 4038: 4034: 4026:Fleming (1934) 4025: 4021: 4011: 4009: 4008:on 28 June 2013 4000: 3999: 3995: 3980:White, Thomas, 3978: 3974: 3943: 3939: 3928: 3919: 3910: 3908: 3904: 3884: 3880: 3865: 3849: 3845: 3834: 3818: 3814: 3791:(12): 569–575. 3777: 3773: 3766: 3752: 3748: 3741: 3727: 3720: 3709: 3695: 3691: 3680: 3676: 3659: 3655: 3645: 3643: 3635: 3634: 3630: 3623: 3611: 3610: 3606: 3598: 3592: 3581: 3573: 3569: 3564: 3559: 3550:Valve amplifier 3476: 3469: 3466: 3451: 3443: 3431: 3428: 3420: 3395: 3389: 3383: 3377: 3374: 3368: 3365: 3359: 3328: 3311: 3298: 3296:Characteristics 3258:(for example a 3240: 3229: 3223: 3220: 3177: 3175: 3165: 3153: 3142: 3136: 3109: 3104: 3077:audio amplifier 3069: 3063: 3051:gallium nitride 2988: 2983: 2923:photomultiplier 2919: 2911:Main articles: 2909: 2868:magic eye tubes 2848: 2842: 2833:microwave ovens 2806:microwave ovens 2802: 2783: 2777: 2754: 2719: 2684: 2679: 2671:aluminium oxide 2663:strontium oxide 2655: 2653:Receiving tubes 2617: 2609:image orthicons 2562: 2558: 2554: 2514: 2433: 2371:household power 2359: 2352: 2333:cathode biasing 2269: 2263: 2258: 2222: 2125: 2087: 2034: 2022:deionized water 1977: 1970: 1866: 1860: 1806: 1800: 1784:Ferranti Mark 1 1742: 1731: 1725: 1701: 1687:Irving Langmuir 1658: 1629: 1625: 1614: 1592: 1588: 1576: 1572: 1564: 1560: 1553: 1551:Miniature tubes 1524:discharge tubes 1517: 1505:beam power tube 1461: 1455: 1433:beam deflection 1322: 1314:beam power tube 1296:suppressor grid 1262:dynatron region 1204: 1196:Main articles: 1194: 1162:cathode biasing 1115: 1111: 1106: 1097: 1093: 1091: 1088: 1087: 1084: 1078: 1075: 1069: 1066: 1060: 1057: 1051: 1028:10 Torr). 1025: 1017: 996:) had improved 986:Irving Langmuir 975:Eric Tigerstedt 942: 865: 859: 792:Marconi Company 777: 771: 699:Eugen Goldstein 671: 545:, containing a 507: 506: 505: 504: 503: 497: 489: 488: 474: 463: 295: 293:Classifications 255:. However, the 96:thermionic tube 79:flow in a high 43: 28: 23: 22: 15: 12: 11: 5: 7543: 7533: 7532: 7527: 7522: 7517: 7512: 7507: 7502: 7497: 7480: 7479: 7477: 7476: 7471: 7465: 7463: 7459: 7458: 7456: 7455: 7450: 7445: 7440: 7435: 7430: 7424: 7422: 7418: 7417: 7415: 7414: 7409: 7404: 7399: 7394: 7389: 7384: 7379: 7374: 7372:Selectron tube 7369: 7364: 7359: 7354: 7349: 7344: 7339: 7334: 7329: 7324: 7319: 7314: 7309: 7304: 7299: 7294: 7289: 7284: 7278: 7273: 7268: 7263: 7258: 7253: 7248: 7243: 7237: 7235: 7229: 7228: 7226: 7225: 7220: 7215: 7210: 7205: 7200: 7195: 7190: 7185: 7179: 7177: 7173: 7172: 7165: 7164: 7157: 7150: 7142: 7133: 7132: 7130: 7129: 7128: 7127: 7122: 7112: 7107: 7102: 7097: 7092: 7091: 7090: 7079: 7077: 7071: 7070: 7068: 7067: 7066: 7065: 7063:Wollaston wire 7055: 7050: 7045: 7040: 7035: 7030: 7029: 7028: 7023: 7013: 7008: 7003: 6998: 6997: 6996: 6991: 6986: 6977: 6975: 6971: 6970: 6968: 6967: 6962: 6957: 6956: 6955: 6944: 6942: 6938: 6937: 6935: 6934: 6929: 6924: 6919: 6914: 6909: 6904: 6899: 6894: 6889: 6884: 6878: 6876: 6870: 6869: 6867: 6866: 6861: 6856: 6851: 6846: 6844:Selectron tube 6841: 6836: 6834:Magic eye tube 6831: 6826: 6821: 6815: 6813: 6807: 6806: 6804: 6803: 6798: 6792: 6787: 6782: 6777: 6771: 6766: 6760: 6755: 6748: 6746: 6735: 6734: 6732: 6731: 6726: 6721: 6716: 6711: 6706: 6700: 6695: 6690: 6685: 6680: 6675: 6670: 6665: 6660: 6655: 6649: 6647: 6641: 6640: 6638: 6637: 6632: 6627: 6622: 6617: 6612: 6607: 6602: 6597: 6592: 6587: 6581: 6579: 6573: 6572: 6569: 6568: 6566: 6565: 6560: 6555: 6550: 6545: 6539: 6533: 6528: 6522: 6517: 6512: 6507: 6502: 6496: 6491: 6485: 6480: 6475: 6470: 6465: 6459: 6454: 6448: 6443: 6438: 6433: 6427: 6425: 6419: 6418: 6416: 6415: 6410: 6405: 6403:Schottky diode 6400: 6395: 6390: 6384: 6378: 6372: 6367: 6361: 6355: 6353: 6347: 6346: 6344: 6343: 6337: 6332: 6326: 6320: 6315: 6310: 6309: 6308: 6297: 6296: 6295: 6290: 6279: 6274: 6269: 6262: 6260: 6252: 6251: 6249: 6248: 6243: 6238: 6232: 6227: 6221: 6215: 6210: 6205: 6199: 6193: 6187: 6182: 6176: 6170: 6165: 6160: 6155: 6150: 6144: 6142: 6131: 6123: 6122: 6115: 6114: 6107: 6100: 6092: 6086: 6085: 6080: 6068: 6063: 6057: 6048: 6043: 6038: 6032: 6019: 6011: 6010:External links 6008: 6007: 6006: 6000: 5993: 5985: 5978: 5971: 5966:Stokes, John, 5964: 5937: 5934: 5927: 5918: 5915: 5908: 5899: 5896: 5894: 5893: 5887: 5875:Smith, Michael 5871: 5865: 5851: 5849: 5846: 5843: 5842: 5833: 5822: 5810: 5791: 5760: 5735: 5712: 5669: 5646: 5627: 5615: 5571: 5524:(2): 101–108. 5504: 5489: 5463: 5457:978-1891121524 5456: 5434: 5416: 5401: 5382: 5371:. 16 June 2000 5360: 5338: 5324: 5312: 5300: 5288: 5258: 5241: 5221: 5200: 5175: 5160: 5144: 5127: 5112: 5103: 5094: 5076: 5065: 5045: 5031: 5019: 4992: 4980: 4940: 4907: 4901:978-3486856705 4900: 4877: 4857: 4845: 4833: 4821: 4804: 4787:Computer World 4773: 4753: 4728: 4697: 4676: 4656: 4641: 4624: 4607: 4592: 4577: 4561: 4546: 4532: 4518: 4504: 4500:) of the tube. 4497: 4487: 4458: 4431: 4424: 4406: 4380: 4361: 4346: 4333: 4318: 4301: 4266: 4251: 4242: 4216: 4210:978-1580536691 4209: 4183: 4157: 4142: 4125: 4093: 4078: 4063: 4048: 4044:Wireless World 4032: 4019: 4002:"Mazda Valves" 3993: 3972: 3937: 3917: 3902: 3878: 3863: 3843: 3832: 3812: 3771: 3765:978-1489965356 3764: 3746: 3740:978-0080966403 3739: 3718: 3707: 3689: 3674: 3653: 3628: 3622:978-0905705934 3621: 3604: 3591:978-1258664060 3590: 3566: 3565: 3563: 3560: 3558: 3557: 3552: 3547: 3542: 3537: 3532: 3527: 3522: 3519:display device 3517:—a gas-filled 3512: 3507: 3502: 3496: 3490: 3483: 3482: 3481: 3465: 3462: 3461: 3460: 3449: 3441: 3427: 3424: 3419: 3416: 3415: 3414: 3411: 3408: 3405: 3393: 3381: 3372: 3363: 3327: 3324: 3320:electric field 3310: 3307: 3297: 3294: 3242: 3241: 3156: 3154: 3147: 3138:Main article: 3135: 3132: 3108: 3105: 3103: 3100: 3065:Main article: 3062: 3059: 3043:microwave oven 2987: 2984: 2982: 2979: 2908: 2905: 2872:meter movement 2844:Main article: 2841: 2838: 2801: 2798: 2779:Main article: 2776: 2773: 2753: 2752:Other failures 2750: 2718: 2715: 2696:inrush current 2683: 2680: 2678: 2675: 2654: 2651: 2616: 2613: 2565:10 atm). 2550:mean free path 2545:glow discharge 2513: 2510: 2432: 2429: 2391:direct current 2351: 2348: 2265:Main article: 2262: 2259: 2257: 2254: 2203:nuclear weapon 2190:, also called 2124: 2121: 2086: 2083: 2033: 2030: 1969: 1966: 1923:stress testing 1884:, used in the 1862:Main article: 1859: 1856: 1842:Heath Robinson 1834:Bletchley Park 1818:Bletchley Park 1802:Main article: 1799: 1796: 1724: 1721: 1700: 1697: 1683:diffusion pump 1657: 1654: 1630:11 mm diameter 1613: 1610: 1593:10 mm diameter 1552: 1549: 1530:tubes are not 1516: 1513: 1511:power output. 1457:Main article: 1454: 1451: 1321: 1318: 1193: 1190: 1181:neutralization 1118: 1114: 1110: 1105: 1100: 1096: 1082: 1073: 1064: 1055: 998:Wolfgang Gaede 911:vacuum tubes. 861:Main article: 858: 855: 773:Main article: 770: 767: 670: 667: 498: 491: 490: 475: 468: 467: 466: 465: 464: 462: 459: 423: 422: 403: 400: 393: 390: 383: 368: 365: 301:Radio station 294: 291: 220:networks, and 136:electric field 36:Pneumatic tube 26: 9: 6: 4: 3: 2: 7542: 7531: 7528: 7526: 7523: 7521: 7518: 7516: 7513: 7511: 7508: 7506: 7503: 7501: 7498: 7496: 7493: 7492: 7490: 7475: 7472: 7470: 7467: 7466: 7464: 7460: 7454: 7451: 7449: 7446: 7444: 7441: 7439: 7438:Marconi-Osram 7436: 7434: 7431: 7429: 7426: 7425: 7423: 7419: 7413: 7412:Fleming valve 7410: 7408: 7407:Williams tube 7405: 7403: 7400: 7398: 7395: 7393: 7390: 7388: 7385: 7383: 7380: 7378: 7375: 7373: 7370: 7368: 7365: 7363: 7360: 7358: 7355: 7353: 7350: 7348: 7345: 7343: 7340: 7338: 7335: 7333: 7330: 7328: 7325: 7323: 7320: 7318: 7315: 7313: 7310: 7308: 7305: 7303: 7300: 7298: 7295: 7293: 7290: 7288: 7285: 7282: 7279: 7277: 7274: 7272: 7269: 7267: 7264: 7262: 7259: 7257: 7254: 7252: 7249: 7247: 7244: 7242: 7239: 7238: 7236: 7234: 7230: 7224: 7221: 7219: 7218:Glowing anode 7216: 7214: 7211: 7209: 7206: 7204: 7201: 7199: 7196: 7194: 7191: 7189: 7188:Work function 7186: 7184: 7181: 7180: 7178: 7174: 7170: 7163: 7158: 7156: 7151: 7149: 7144: 7143: 7140: 7126: 7125:mercury relay 7123: 7121: 7118: 7117: 7116: 7113: 7111: 7108: 7106: 7103: 7101: 7098: 7096: 7093: 7089: 7086: 7085: 7084: 7081: 7080: 7078: 7076: 7072: 7064: 7061: 7060: 7059: 7056: 7054: 7051: 7049: 7046: 7044: 7041: 7039: 7036: 7034: 7031: 7027: 7024: 7022: 7019: 7018: 7017: 7014: 7012: 7009: 7007: 7004: 7002: 6999: 6995: 6992: 6990: 6987: 6985: 6982: 6981: 6979: 6978: 6976: 6972: 6966: 6963: 6961: 6958: 6954: 6951: 6950: 6949: 6948:Potentiometer 6946: 6945: 6943: 6939: 6933: 6930: 6928: 6925: 6923: 6920: 6918: 6915: 6913: 6910: 6908: 6905: 6903: 6900: 6898: 6895: 6893: 6890: 6888: 6885: 6883: 6880: 6879: 6877: 6875: 6871: 6865: 6864:Williams tube 6862: 6860: 6857: 6855: 6852: 6850: 6847: 6845: 6842: 6840: 6837: 6835: 6832: 6830: 6827: 6825: 6822: 6820: 6817: 6816: 6814: 6812: 6808: 6802: 6799: 6796: 6793: 6791: 6788: 6786: 6783: 6781: 6778: 6775: 6772: 6770: 6767: 6764: 6761: 6759: 6756: 6753: 6750: 6749: 6747: 6744: 6740: 6736: 6730: 6727: 6725: 6722: 6720: 6717: 6715: 6712: 6710: 6707: 6704: 6701: 6699: 6696: 6694: 6691: 6689: 6686: 6684: 6683:Fleming valve 6681: 6679: 6676: 6674: 6671: 6669: 6666: 6664: 6661: 6659: 6656: 6654: 6651: 6650: 6648: 6646: 6642: 6636: 6633: 6631: 6628: 6626: 6623: 6621: 6618: 6616: 6613: 6611: 6608: 6606: 6603: 6601: 6598: 6596: 6593: 6591: 6588: 6586: 6583: 6582: 6580: 6578: 6574: 6564: 6561: 6559: 6556: 6554: 6551: 6549: 6546: 6543: 6540: 6537: 6534: 6532: 6529: 6526: 6523: 6521: 6518: 6516: 6513: 6511: 6510:Photodetector 6508: 6506: 6503: 6500: 6497: 6495: 6492: 6489: 6486: 6484: 6481: 6479: 6478:Memtransistor 6476: 6474: 6471: 6469: 6466: 6463: 6460: 6458: 6455: 6452: 6449: 6447: 6444: 6442: 6439: 6437: 6434: 6432: 6429: 6428: 6426: 6420: 6414: 6411: 6409: 6406: 6404: 6401: 6399: 6396: 6394: 6391: 6388: 6385: 6382: 6379: 6376: 6373: 6371: 6368: 6365: 6362: 6360: 6357: 6356: 6354: 6352: 6348: 6341: 6338: 6336: 6333: 6330: 6327: 6324: 6321: 6319: 6316: 6314: 6311: 6307: 6304: 6303: 6301: 6298: 6294: 6291: 6289: 6286: 6285: 6283: 6280: 6278: 6275: 6273: 6270: 6267: 6264: 6263: 6261: 6259: 6253: 6247: 6244: 6242: 6239: 6236: 6233: 6231: 6228: 6225: 6222: 6219: 6216: 6214: 6211: 6209: 6206: 6203: 6200: 6197: 6194: 6191: 6188: 6186: 6183: 6180: 6177: 6174: 6171: 6169: 6166: 6164: 6161: 6159: 6156: 6154: 6151: 6149: 6146: 6145: 6143: 6141: 6135: 6132: 6130: 6127:Semiconductor 6124: 6120: 6113: 6108: 6106: 6101: 6099: 6094: 6093: 6090: 6084: 6081: 6079: 6075: 6072: 6069: 6067: 6064: 6061: 6058: 6056: 6052: 6049: 6047: 6044: 6042: 6039: 6036: 6033: 6030: 6026: 6023: 6020: 6017: 6014: 6013: 6004: 6001: 5998: 5994: 5991: 5990: 5986: 5983: 5979: 5976: 5972: 5969: 5965: 5961: 5957: 5953: 5949: 5945: 5944: 5938: 5935: 5932: 5928: 5925: 5924: 5919: 5916: 5913: 5909: 5906: 5902: 5901: 5890: 5884: 5880: 5876: 5872: 5868: 5866:1-84354-330-3 5862: 5858: 5853: 5852: 5837: 5831: 5826: 5819: 5814: 5806: 5802: 5795: 5779: 5775: 5771: 5764: 5745: 5739: 5723: 5716: 5708: 5704: 5700: 5696: 5692: 5688: 5685:(2): 025010. 5684: 5680: 5673: 5665: 5661: 5660:IEEE Spectrum 5657: 5650: 5643: 5639: 5636: 5631: 5622: 5620: 5610: 5605: 5601: 5597: 5594:(3): 034801. 5593: 5589: 5582: 5575: 5567: 5563: 5558: 5553: 5549: 5545: 5540: 5535: 5531: 5527: 5523: 5519: 5515: 5508: 5500: 5496: 5492: 5486: 5482: 5478: 5475:. p. 1. 5474: 5467: 5459: 5453: 5449: 5445: 5438: 5432: 5428: 5425: 5420: 5412: 5405: 5397: 5393: 5386: 5370: 5364: 5352: 5348: 5342: 5336: 5333: 5328: 5322: 5316: 5310: 5304: 5298: 5292: 5276: 5272: 5268: 5262: 5255: 5251: 5245: 5238: 5234: 5228: 5226: 5218: 5214: 5210: 5204: 5196: 5192: 5188: 5187: 5179: 5172: 5171: 5164: 5157: 5155: 5148: 5141: 5137: 5131: 5124: 5123: 5116: 5107: 5098: 5092: 5088: 5085: 5080: 5072: 5068: 5062: 5058: 5057: 5049: 5043: 5040: 5035: 5028: 5023: 5016: 5009: 5002: 4996: 4989: 4984: 4976: 4964: 4959: 4958: 4951: 4944: 4925: 4918: 4911: 4903: 4897: 4893: 4886: 4884: 4882: 4873: 4866: 4864: 4862: 4854: 4849: 4842: 4837: 4830: 4825: 4817: 4816: 4808: 4792: 4788: 4784: 4777: 4770: 4766: 4762: 4756: 4750: 4746: 4739: 4737: 4735: 4733: 4724: 4720: 4716: 4712: 4708: 4701: 4694: 4693:0-408-00168-2 4690: 4686: 4680: 4673: 4669: 4666: 4660: 4653: 4652: 4648:RCA, (1954). 4645: 4638: 4634: 4628: 4621: 4617: 4611: 4604: 4603: 4596: 4589: 4588: 4581: 4574: 4571: 4565: 4558: 4557: 4550: 4544: 4541: 4536: 4530: 4527: 4522: 4516: 4513: 4508: 4501: 4495: 4490: 4484: 4480: 4475: 4474: 4468: 4462: 4446: 4442: 4435: 4427: 4421: 4417: 4410: 4394: 4390: 4384: 4377: 4373: 4370: 4365: 4358: 4357: 4350: 4343: 4337: 4330: 4329: 4322: 4315: 4311: 4305: 4297: 4293: 4289: 4285: 4281: 4277: 4270: 4263: 4262: 4255: 4246: 4231: 4227: 4220: 4212: 4206: 4202: 4197: 4196: 4187: 4171: 4167: 4161: 4154: 4153: 4146: 4139: 4135: 4129: 4110: 4103: 4097: 4090: 4089: 4082: 4075: 4074: 4067: 4060: 4059: 4052: 4045: 4042: 4036: 4029: 4028:pp. 138 - 143 4023: 4007: 4003: 3997: 3989: 3985: 3984: 3976: 3968: 3964: 3960: 3956: 3952: 3948: 3941: 3934: 3933: 3926: 3924: 3922: 3913: 3906: 3898: 3894: 3893: 3888: 3882: 3874: 3870: 3866: 3864:90-5199-145-2 3860: 3856: 3855: 3847: 3839: 3835: 3833:9780852962183 3829: 3825: 3824: 3816: 3810: 3803: 3798: 3794: 3790: 3786: 3782: 3775: 3767: 3761: 3757: 3750: 3742: 3736: 3732: 3725: 3723: 3715: 3710: 3704: 3700: 3693: 3686: 3685: 3678: 3671: 3667: 3663: 3657: 3642: 3638: 3632: 3624: 3618: 3614: 3608: 3597: 3593: 3587: 3580: 3579: 3571: 3567: 3556: 3553: 3551: 3548: 3546: 3543: 3541: 3538: 3536: 3533: 3531: 3528: 3526: 3523: 3520: 3516: 3513: 3511: 3508: 3506: 3503: 3500: 3497: 3494: 3491: 3488: 3485: 3484: 3479: 3473: 3468: 3459: 3454: 3450: 3446: 3442: 3439: 3438:Fleming valve 3434: 3430: 3429: 3423: 3412: 3409: 3406: 3403: 3402: 3401: 3398: 3392: 3386: 3380: 3371: 3362: 3357: 3352: 3350: 3345: 3341: 3337: 3333: 3323: 3321: 3317: 3302: 3293: 3290: 3288: 3284: 3280: 3276: 3272: 3268: 3263: 3261: 3257: 3253: 3249: 3238: 3235: 3227: 3216: 3213: 3209: 3206: 3202: 3199: 3195: 3192: 3188: 3185: – 3184: 3183:"Vacuum tube" 3180: 3179:Find sources: 3173: 3169: 3163: 3162: 3157:This section 3155: 3151: 3146: 3145: 3141: 3131: 3129: 3126: 3122: 3118: 3114: 3099: 3096: 3091: 3089: 3085: 3078: 3073: 3068: 3058: 3054: 3052: 3048: 3044: 3040: 3036: 3032: 3028: 3024: 3020: 3015: 3013: 3008: 3004: 3000: 2995: 2993: 2978: 2975: 2971: 2969: 2965: 2959: 2955: 2953: 2949: 2945: 2941: 2936: 2932: 2928: 2924: 2918: 2914: 2904: 2902: 2898: 2894: 2890: 2886: 2884: 2879: 2877: 2873: 2869: 2865: 2861: 2860:oscilloscopes 2857: 2853: 2847: 2837: 2834: 2830: 2826: 2822: 2818: 2814: 2809: 2807: 2797: 2792: 2787: 2782: 2772: 2769: 2766: 2761: 2760: 2749: 2747: 2741: 2739: 2734: 2730: 2727: 2722: 2714: 2711: 2708: 2704: 2701: 2697: 2693: 2688: 2677:Failure modes 2674: 2672: 2668: 2667:calcium oxide 2664: 2660: 2650: 2647: 2643: 2639: 2635: 2630: 2626: 2622: 2612: 2610: 2606: 2602: 2598: 2593: 2591: 2587: 2582: 2579: 2575: 2571: 2566: 2551: 2546: 2542: 2538: 2529: 2522: 2518: 2509: 2507: 2502: 2499: 2497: 2496:glowing plate 2492: 2490: 2486: 2481: 2476: 2472: 2470: 2464: 2462: 2457: 2453: 2449: 2441: 2437: 2428: 2424: 2422: 2418: 2413: 2411: 2406: 2404: 2400: 2394: 2392: 2388: 2384: 2380: 2376: 2372: 2368: 2364: 2357: 2347: 2345: 2341: 2336: 2334: 2329: 2325: 2317: 2312: 2308: 2305: 2301: 2296: 2293: 2289: 2286:battery. The 2285: 2281: 2277: 2273: 2268: 2253: 2249: 2247: 2243: 2242:scintillation 2239: 2235: 2231: 2227: 2221: 2216: 2214: 2210: 2206: 2204: 2200: 2195: 2193: 2189: 2185: 2181: 2177: 2172: 2170: 2165: 2161: 2158:, which will 2157: 2153: 2149: 2145: 2141: 2133: 2129: 2120: 2118: 2113: 2110: 2105: 2101: 2095: 2093: 2082: 2080: 2074: 2072: 2066: 2064: 2059: 2055: 2046: 2038: 2032:Tube packages 2029: 2025: 2023: 2017: 2015: 2009: 2007: 2001: 1999: 1995: 1990: 1986: 1974: 1965: 1963: 1958: 1953: 1951: 1947: 1943: 1939: 1935: 1931: 1926: 1924: 1920: 1919:thermal shock 1915: 1910: 1908: 1904: 1900: 1895: 1891: 1887: 1883: 1875: 1870: 1865: 1855: 1853: 1852:Tommy Flowers 1849: 1847: 1843: 1839: 1835: 1831: 1827: 1826:Tommy Flowers 1819: 1815: 1810: 1805: 1795: 1791: 1789: 1785: 1781: 1777: 1773: 1769: 1765: 1761: 1757: 1756:Tommy Flowers 1752: 1740: 1735: 1730: 1720: 1717: 1714: 1710: 1707: 1696: 1693: 1688: 1684: 1680: 1676: 1672: 1662: 1653: 1651: 1647: 1643: 1639: 1624:" triode, c. 1623: 1618: 1609: 1607: 1602: 1585: 1570: 1557: 1548: 1546: 1541: 1537: 1533: 1529: 1525: 1521: 1512: 1508: 1506: 1502: 1498: 1493: 1490: 1486: 1482: 1478: 1469: 1465: 1460: 1450: 1448: 1447:(de)modulator 1445: 1441: 1438: 1434: 1429: 1427: 1423: 1418: 1416: 1412: 1408: 1404: 1400: 1396: 1392: 1387: 1385: 1381: 1376: 1374: 1370: 1366: 1365:control grids 1362: 1358: 1354: 1350: 1346: 1342: 1338: 1331: 1326: 1317: 1315: 1311: 1306: 1302: 1297: 1293: 1288: 1286: 1282: 1278: 1273: 1271: 1267: 1263: 1258: 1249: 1245: 1243: 1239: 1235: 1231: 1230: 1224: 1220: 1212: 1208: 1203: 1199: 1189: 1187: 1182: 1177: 1175: 1169: 1165: 1163: 1158: 1156: 1152: 1151: 1145: 1142: 1137: 1133: 1116: 1112: 1108: 1103: 1098: 1094: 1081: 1072: 1063: 1054: 1048: 1046: 1042: 1038: 1034: 1029: 1023: 1015: 1011: 1006: 1003: 999: 995: 991: 987: 983: 980: 979:sound-on-film 976: 971: 968: 960: 956: 952: 948: 945: 940: 939:amplification 934: 932: 928: 924: 920: 916: 915:Lee de Forest 912: 910: 905: 901: 892: 884: 877: 874: 869: 864: 854: 852: 847: 845: 841: 840:Fleming valve 837: 836: 831: 830: 824: 819: 817: 813: 809: 805: 801: 797: 793: 785: 781: 776: 766: 764: 760: 756: 752: 748: 747:Lee de Forest 743: 741: 737: 733: 729: 728: 727:Edison effect 723: 719: 714: 712: 708: 704: 700: 696: 695:Thomas Edison 692: 691:Crookes tubes 688: 680: 675: 666: 664: 660: 656: 652: 648: 642: 640: 636: 632: 628: 626: 621: 615: 613: 607: 605: 601: 597: 593: 592: 587: 586:rectification 583: 579: 575: 571: 570: 569:Edison effect 565: 561: 557: 556: 551: 548: 544: 539: 536: 532: 528: 524: 520: 516: 512: 501: 495: 486: 482: 478: 472: 458: 456: 452: 448: 444: 440: 436: 432: 428: 420: 416: 412: 408: 404: 401: 398: 394: 391: 388: 384: 381: 377: 373: 369: 366: 363: 359: 355: 351: 347: 346: 345: 342: 340: 336: 332: 328: 327:amplification 324: 320: 319:rectification 316: 312: 304: 299: 290: 288: 284: 279: 277: 273: 269: 264: 262: 261:oscilloscopes 258: 254: 250: 246: 241: 239: 235: 232:for radio or 231: 227: 223: 219: 215: 211: 207: 203: 198: 196: 195:control grids 192: 188: 187:Fleming valve 184: 176: 172: 168: 164: 160: 155: 148: 143: 139: 138:in the tube. 137: 133: 129: 125: 121: 120:rectification 117: 116:amplification 113: 109: 105: 101: 97: 92: 90: 86: 82: 78: 74: 70: 66: 65:electron tube 62: 54: 49: 45: 41: 37: 33: 19: 7495:Vacuum tubes 7377:Storage tube 7271:Beam tetrode 7203:Control grid 7198:Space charge 7168: 6882:Cold cathode 6849:Storage tube 6739:Vacuum tubes 6738: 6688:Neutron tube 6663:Beam tetrode 6645:Vacuum tubes 6644: 6230:Power MOSFET 6005:; 1940; RCA. 5996: 5987: 5981: 5974: 5967: 5943:Vacuum Tubes 5942: 5930: 5921: 5911: 5904: 5878: 5856: 5848:Bibliography 5836: 5825: 5817: 5813: 5794: 5782:. Retrieved 5773: 5763: 5751:. Retrieved 5738: 5726:. Retrieved 5715: 5682: 5678: 5672: 5659: 5649: 5630: 5591: 5587: 5574: 5521: 5517: 5507: 5472: 5466: 5447: 5437: 5419: 5404: 5395: 5385: 5373:. Retrieved 5363: 5341: 5334: 5327: 5315: 5303: 5291: 5279:. Retrieved 5270: 5261: 5253: 5244: 5236: 5208: 5203: 5185: 5178: 5169: 5163: 5153: 5147: 5139: 5130: 5121: 5115: 5106: 5097: 5079: 5055: 5048: 5041: 5034: 5026: 5022: 5014: 4995: 4983: 4973:– via 4967:. Retrieved 4956: 4943: 4931:. Retrieved 4924:the original 4910: 4891: 4871: 4848: 4836: 4824: 4814: 4807: 4795:. Retrieved 4791:the original 4786: 4776: 4744: 4706: 4700: 4684: 4679: 4659: 4650: 4644: 4636: 4627: 4619: 4610: 4601: 4595: 4586: 4580: 4572: 4564: 4555: 4549: 4542: 4535: 4528: 4521: 4514: 4507: 4493: 4492: 4472: 4467:Ballou, Glen 4461: 4449:. Retrieved 4445:the original 4434: 4415: 4409: 4397:. Retrieved 4383: 4364: 4355: 4349: 4341: 4336: 4327: 4321: 4313: 4304: 4282:(2): 52–54. 4279: 4275: 4269: 4260: 4254: 4245: 4233:. 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Retrieved 3640: 3631: 3612: 3607: 3577: 3570: 3421: 3399: 3390: 3387: 3378: 3369: 3360: 3355: 3353: 3348: 3344:space charge 3343: 3339: 3335: 3329: 3316:space charge 3312: 3291: 3264: 3252:cold cathode 3245: 3230: 3221: 3211: 3204: 3197: 3190: 3178: 3166:Please help 3161:verification 3158: 3110: 3092: 3081: 3055: 3016: 2996: 2989: 2972: 2960: 2956: 2920: 2893:relativistic 2887: 2880: 2849: 2821:Carcinotrons 2810: 2803: 2795: 2770: 2759:Microphonics 2757: 2755: 2742: 2735: 2731: 2723: 2720: 2712: 2705: 2689: 2685: 2659:barium oxide 2656: 2618: 2594: 2567: 2536: 2534: 2503: 2500: 2493: 2477: 2473: 2465: 2445: 2425: 2421:cheater cord 2420: 2414: 2407: 2395: 2375:power supply 2369:operated by 2360: 2356:Cheater plug 2344:battery size 2337: 2327: 2321: 2297: 2283: 2279: 2275: 2270: 2250: 2223: 2207: 2196: 2173: 2137: 2114: 2104:designations 2096: 2088: 2075: 2067: 2051: 2026: 2018: 2010: 2002: 1991: 1987: 1983: 1954: 1927: 1911: 1894:barium oxide 1878: 1850: 1845: 1823: 1792: 1748: 1718: 1715: 1711: 1702: 1671:vacuum pumps 1668: 1634: 1598: 1579:in diameter. 1563:high with a 1531: 1528:cold cathode 1518: 1509: 1504: 1500: 1497:beam pentode 1496: 1494: 1485:space charge 1477:beam tetrode 1474: 1468:Beam tetrode 1459:Beam tetrode 1440:demodulation 1430: 1419: 1403:preamplifier 1388: 1379: 1377: 1369:screen grids 1359:and even an 1335: 1313: 1310:beam tetrode 1300: 1289: 1285:tunnel diode 1274: 1266:tetrode kink 1265: 1261: 1254: 1242:control grid 1233: 1227: 1222: 1216: 1180: 1178: 1170: 1166: 1159: 1148: 1146: 1138: 1134: 1079: 1070: 1061: 1052: 1049: 1040: 1036: 1030: 1007: 984: 972: 963: 935: 931:control grid 913: 897: 848: 833: 827: 822: 820: 789: 786:first diodes 744: 725: 715: 703:Nikola Tesla 684: 658: 643: 638: 629: 616: 608: 596:power supply 589: 577: 567: 553: 540: 508: 453:rather than 424: 380:warm-up time 343: 308: 280: 265: 242: 199: 180: 118:and current 99: 95: 93: 72: 68: 64: 60: 58: 44: 7382:Sutton tube 7193:Hot cathode 7048:Transformer 6790:Sutton tube 6630:Charge pump 6483:Memory cell 6413:Zener diode 6375:Laser diode 6258:transistors 6140:transistors 5912:Electronics 5321:pp. 30 - 33 5309:pp. 34 - 35 5297:pp. 17 - 20 5281:29 December 5254:Electronics 4969:10 December 4933:12 February 4853:Gannon 2006 4841:Gannon 2006 4620:Electronics 4235:12 November 3545:Tube tester 3487:Bogey value 3117:televisions 2992:solid-state 2791:tube tester 2781:Tube tester 2601:iconoscopes 2459:similar to 2440:Tube tester 2431:Reliability 2379:transformer 2324:"C" battery 2316:"C" battery 2300:"B" battery 2288:"A" battery 2209:X-ray tubes 2169:gas ionizes 2144:inert gases 2071:capacitance 1764:Post Office 1503:instead of 1234:shield grid 1229:screen grid 804:Edison-Swan 711:light bulbs 612:H. J. Round 600:demodulator 558:) releases 527:tube socket 461:Description 439:X-ray tubes 407:information 249:solid-state 238:electronics 108:hot cathode 61:vacuum tube 7489:Categories 7397:Trochotron 7327:Iconoscope 7317:Compactron 7312:Charactron 7256:Acorn tube 7120:reed relay 7110:Parametron 7043:Thermistor 7021:resettable 6980:Connector 6941:Adjustable 6917:Nixie tube 6887:Crossatron 6854:Trochotron 6829:Iconoscope 6824:Charactron 6801:X-ray tube 6673:Compactron 6653:Acorn tube 6610:Buck–boost 6531:Solaristor 6393:Photodiode 6370:Gunn diode 6366:(CLD, CRD) 6148:Transistor 6029:Archive-It 5784:8 February 5408:Coolidge, 5347:US 5463290 5217:1483223558 4829:Smith 1998 4637:RCA Review 4399:3 November 4012:12 January 3670:9027248761 3562:References 3540:Tube caddy 3515:Nixie tube 3194:newspapers 3128:flat panel 3088:audiophile 3084:warm sound 3067:Tube sound 3001:effect of 2883:X-ray tube 2813:magnetrons 2700:thermistor 2469:thermistor 2452:ionization 2387:capacitors 2383:rectifiers 2218:See also: 2213:CT imaging 2192:thyristors 2006:thyratrons 1998:Convection 1978:500 W 1964:possible. 1727:See also: 1638:acorn tube 1626:20 mm high 1620:RCA 6DS4 " 1606:rectifiers 1589:35 mm long 1426:Compactron 1339:require a 1281:LC circuit 1186:Neutrodyne 844:rectifying 639:collectors 635:magnetrons 511:electrodes 443:phototubes 311:electrodes 276:tube sound 272:amplifiers 253:transistor 224:and early 206:television 167:impedances 112:electronic 85:electrodes 53:thermionic 40:Vacutainer 7362:Phototube 7357:Monoscope 7352:Magnetron 7347:Magic eye 7337:Kinescope 7281:Pentagrid 7083:Capacitor 6927:Trigatron 6922:Thyratron 6912:Neon lamp 6839:Monoscope 6719:Phototube 6703:Pentagrid 6668:Barretter 6553:Trancitor 6548:Thyristor 6473:Memristor 6398:PIN diode 6175:(ChemFET) 5960:TK7872.V3 5728:8 October 5548:0909-0495 5375:4 October 5271:31 Alumni 5233:"Getters" 4176:21 August 3283:satellite 3271:Bluetooth 3267:microwave 3047:magnetron 2974:Tektronix 2927:phototube 2889:Gyrotrons 2825:klystrons 2605:orthicons 2590:zirconium 2417:interlock 2292:lead-acid 2272:Batteries 2261:Batteries 2176:jukeboxes 2164:thyratron 1907:silicates 1874:Whirlwind 1820:, England 1780:Whirlwind 1745:of power. 1737:The 1946 1575:high and 1540:thyratron 1471:and size. 1384:Loewe 3NF 1150:grid bias 1109:μ 1024:down to 8 873:de Forest 784:Fleming's 736:detection 716:Although 631:Klystrons 625:radiation 591:rectifier 560:electrons 521:sealable 517:based on 433:, and in 362:microwave 352:, radio, 331:switching 325:used for 268:magnetron 218:telephone 175:inductors 171:resistors 124:phototube 102:utilizes 32:Free fall 7462:Examples 7342:Klystron 7322:Eidophor 7297:Additron 7261:Nuvistor 7105:Inductor 7075:Reactive 7053:Varistor 7033:Resistor 7011:Antifuse 6897:Ignitron 6892:Dekatron 6780:Klystron 6769:Gyrotron 6698:Nuvistor 6615:Split-pi 6501:(MOS IC) 6468:Memistor 6226:(MuGFET) 6220:(MOSFET) 6192:(FinFET) 6074:Archived 6025:Archived 5877:(1998). 5805:Archived 5778:Archived 5707:21531107 5664:Archived 5638:Archived 5566:21335894 5499:31007942 5427:Archived 5275:Archived 5195:60-13843 5087:Archived 5071:Archived 5008:Archived 4797:25 April 4765:Archived 4723:41800914 4668:Archived 4469:(1987). 4451:22 April 4393:Archived 4372:Archived 4296:42357863 4170:Archived 4118:30 March 4109:Archived 3988:archived 3967:23351454 3889:(1876). 3873:30995577 3838:Archived 3646:13 April 3596:Archived 3555:Zetatron 3464:See also 3334:) input 3224:May 2018 3102:Displays 3061:In music 3035:klystron 2621:tungsten 2448:poisoned 2377:using a 2350:AC power 2328:negative 2304:dry cell 2184:ignitron 2146:such as 2102:(RETMA) 2063:nuvistor 1980:of heat. 1901:drawing 1886:tungsten 1798:Colossus 1788:UNIVAC I 1760:Colossus 1642:nuvistor 1622:nuvistor 1601:bakelite 1522:such as 1238:bypassed 1020:10 808:detector 687:Geissler 679:Edison's 547:filament 376:filament 339:pentodes 335:tetrodes 83:between 7453:Russian 7276:Pentode 7266:Tetrode 7006:Ferrite 6974:Passive 6965:Varicap 6953:digital 6902:Krytron 6724:Tetrode 6709:Pentode 6563:Varicap 6544:(3D IC) 6520:RF CMOS 6424:devices 6198:(FGMOS) 6129:devices 5753:12 June 5687:Bibcode 5596:Bibcode 5557:3042323 5526:Bibcode 5219:page 96 5156:2nd ed. 4140:. p. 44 3826:. IET. 3440:patent) 3426:Patents 3340:current 3336:voltage 3208:scholar 3045:uses a 2775:Testing 2638:WAAY-TV 2629:diffuse 2625:thorium 2570:getters 2489:Fernico 2244:due to 2199:krytron 2112:12AZ7. 2058:ceramic 1950:IBM 701 1882:silicon 1646:thimble 1577:20.4 mm 1545:mercury 1355:with a 1301:pentode 1294:. 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