Talk:Triode

I am afraid that most filaments require a two wire connection to allow current to flow through them to cause heating. The filament heater is sometimes separate and sometimes electricaly isolated from the cathode. So a triode may require 4 or 5 leads. I think leaving this out may confuse some. Perhaps someday more about their history could be added. I believe this invention is attributed to Lee DeForest and that triodes were originally called audions. I also think there was some confusion about the importance of vacuum. I think the issue was resolved with the introduction of the "getter".

See Vacuum tube, we don't need to duplicate this information. In fact it might be good to merge this page with that. --Mystic Pixel 07:21, 9 April 2006 (UTC)

Gas-filled?

I doubt that the British call a VACUUM tube a GAS FILLED tube. One has gas, the other cannot.Thortful 07:25, 10 Nov 2004 (UTC)

I removed the link, it doesn't make sense... --Mystic Pixel 07:23, 9 April 2006 (UTC)

Vacuum tubes and gas filled tubes are both glass tubes that have function in a circuit.. Vacuum Tubes are linked to Gas and vice versa, but it really doesn't matter that much

Well, actually it does matter VERY MUCH. Gas-filled tubes are generally triggerable into conduction (ignitron, thyratron etc), while vacuum tubes can't do that but instead provide fairly linear amplification. As it happens, in the days when valves/tubes were in common use, the best manufacturer, as far as reliability was concerned, was Mullard, and their vacuum pumping and degassing was to a higher standard than their competitors, which is what made the difference. The higher the vacuum, the better, for an amplifying triode. Tiger99 (talk) 14:57, 27 August 2014 (UTC)

De Forest's patent

De Forest thought some gas was necessary to make the Audion work, and this is in his patent. In fact they worked in spite of the gas not because of it. De Forest wasn't worried about the physics except where his patent was affected. PAS 02:46, 18 August 2006 (UTC)

Workings same as transistor?

I know that the triode and the transistor are worlds apart as far as how each works internally. However, can one theoretically replace the other if the transistor is a high power consumption transistor?

They're different in implementation, but not in theory, as far as internal workings. I'm not sure what you're trying to get at (as transistors are normally used to replace triodes, not the other way around) but the answer is quite simple: use a high-power triode. See the Vacuum tube page, where it talks about high-power tubes. --Mystic Pixel 07:21, 9 April 2006 (UTC)

the wikipedia article on valves states that the origional audion (now called a Diode) was invented by John Ambrose Fleming, in 1904, this article seems to contradict this. could anyone explain?220.233.74.219 07:46, 15 May 2007 (UTC)

Don't merge

I don't think the page should be merged with vaccum tube because the term triode has its own meaning in the realm of solid-state electronics. It refers to a mode of operation in which output current is (more or less) linearly dependent on the voltage across the output terminals (drain-source, emitter-collector) voltage, as opposed to operating in the saturation region. I.e., transistors in this region act like resistors.

So, maybe a more general discussion on what triode operation means for vaccum tubes and for transistors is in order.

Also, transistors were initially referred to as triodes themselves (or "crystal triodes"). So, the term triode really describes the function and not the particular technology used.

No

Don't Join Pages It Helped Me alot!

I removed the merge tag. I think the page could eventually have a discussion of triode circuits, etc. Give me some time and I'll get around to some expansion. - mako 21:40, 2 May 2006 (UTC)

OK, I see your point. Fair enough. Mystic Pixel 00:33, 19 May 2006 (UTC)

Triode and Transistor both amplify stuff don't they? Explain it more on the triode article please

• Both are actually one-way resistors that can be controlled. In triodes the resistance between Anode and Cathode is controlled by the voltage between the grid and the cathode, while in transistors the resistance between the emitter and the collector can be controlled by the amount of current flowing into the base. 70.27.152.243 (talk) 16:50, 20 July 2016 (UTC)

... triodes are still more linear at audio-frequency ranges...

This is a rather barmy assertion. All amplifiers use negative feedback to compensate the non-linearities of their amplifying elements. From what I gather, valve amps produce a "warmer" sound because they saturate more gracefully outside their linear range. Transistor amps tend to cut out abruptly outside the linear range, resulting in a harsher sound. (This is discussed a bit in Valve sound).

If people are claiming that valve amps are more linear, then they're wrong. I'm going to delete this statement unless someone can back it up with a reference. -- Sakurambo 桜ん坊 18:36, 11 July 2006 (UTC)

Let us be wary of allowing the nonsense often put about by the so-called high-end audio industry into Wikipedia, without proper evidence. I don't think that anyone intends that, but they do jump on the bandwaggon of linearity, coupled with no feedback, so let's not feed them..... The fact is that a good triode IS more linear than a bipolar transistor over a fair part of its operating region, and is roughly comparable to a JFET. You can just about get away with a triode audio stage with no negative feedback, but never a BJT, unless the signal is very small. Most BJT circuits have in fact got at least local negative feedback, which the inexperienced may not recognise as such. It is true to state that to achieve best accuracy and low distortion, negative feedback is always needed in any amplifier, as an acceptably linear amplifying device has not been invented, and probably can't be, due to the laws of physics, which favour exponential or square laws, or combinations thereof. So I suggest keeping THIS article about the properties of triodes, good and bad, and keep subjectivism elsewhere. Being a circuit designer, I can easily run a SPICE simulation of various circuits, the triode version does indeed always come out much better as regards linearity, as a standalone device, but the BJT allows me to build a more complex circuit ("PNP" valves would be made of anti-matter!) which can partially cancel some distortion mechanisms and allow more forward gain, and the ability to apply far more negative feedback, with resulting better overall performance. Basically, valves by themselves ARE more linear, complete things like amplifiers almost always ARE NOT. And yes, valve distortion mechanisms, along with sensitivity to supply rail ripple, do indeed provide what hard-nosed factual engineers as well as subjectivists will probably agree is a "warmer" sound, however it is an inaccurate sound. So is a "harsh" sound.... Tiger99 (talk) 15:17, 27 August 2014 (UTC)

Characteristics

We could do with a diagram of typical triode electrical characteristic curves.--Light current 19:31, 1 January 2007 (UTC)

Triode region?

A lecturer at MIT talks about a MOSFET getting into its "triode region" (the oppose of saturation), e.g. in relation to small signal analysis. What's a triode region? And what's it got to do with triodes? —Pengo 08:28, 27 August 2007 (UTC) ... it's also mentioned in pMOS logic —Pengo 13:07, 29 August 2007 (UTC)

The triode region is simply the region where it is amplifying. If the grid is too positive, the anode current more or less saturates, anode voltage is very small, and it can't usefully amplify small changes in grid voltage. If the grid is too negative, anode current is cut off, so again no amplification. But like the FET, in the middle region it amplifies. At the lower region of anode or drain current, near cutoff, both triode and FET show a near square law characteristic. The triode is rarely (except in very early computers) used as a switch, whereas almost all MOSFETs are used as switches, either hard on or hard off, going through the triode region as quickly as possible. Tiger99 (talk) 16:34, 18 July 2015 (UTC)

Operation section can be improved.

The first sentence is: The directly-heated cathode (or indirectly by means of a filament) produces an electron charge by thermionic emission when AC is applied. It would be better to say that the cathode emits electrons by thermionic emission and leave out the mention of AC in this first statement as the introduction of the superimposed AC signal is clearly expressed later in the paragraph.184.45.71.182 (talk) 12:15, 10 May 2012 (UTC)

ECC83 Usage

I have changed this on the caption to the picture, because although it was indeed very popular in the 1960s, it was quite rare in TV sets and radios, although occasionally found in stereo radiograms and such like. It was also used briefly in professional audio equipment, before that went solid-state, and is still used in the bogus "high end" audio market. The double triodes found in TV sets were commonly as a cascode in the VHF tuner, ECC84 or ECC85. Single triodes, with pentode, were more common in radios and TV sets. ECC83 is equivalent to 12AX7. Feel free to change or add, if you know more, of course.

Tiger99 (talk) 14:52, 27 August 2014 (UTC)

The Audion was a triode

@Fountains of Bryn Mawr: re your last edits, there are plenty of sources saying the Audion was a triode. I don't care if we co-credit the von Lieben tube as the first triode, but I think that should be in the introduction. --Chetvorno^TALK 21:05, 2 December 2016 (UTC)

I am actually only approaching this as a set/sub-set edit, does one item belong within another? If the lead sentence "Triode is an electronic amplifying vacuum tube" is correct then an Audion is not a Triode since it is an electronic rectifying partial vacuum tube. It could be the lead def is incorrect and any 3 electrode tube, partial or full vacuum, amplifier or not, is called a "Triode". A definition similar to what we have now seems to come up in references, i.e. A Triode is specifically an electronic amplifying high vacuum tube invented in 1913 derived from the Audion[1][2][3] (name coined by William Eccles during WWI[4]). There is even a claim that the name triode is only applied to vacuum tubes which have been evacuated of as much gas as possible (unknown reliability though). Fountains of Bryn Mawr (talk) 02:43, 4 December 2016 (UTC)

I do not see The Foundations of Chaos Revisited: From Poincaré to Recent Advancements edited by Christos Skiadas as a reliable source for a claim about applied electronics. Chaos?

Neither do I see Quo Vadis: Evolution of Modern Navigation: The Rise of Quantum Techniques by Fouad Major as a reliable source for a claim about applied electronics. Navigation?

The Race for Wireless: How Radio was Invented (or Discovered?) by Gregory Malanowski is better, but it does not go into sufficient detail about the controversy. It does acknowledge that the De Forest patent did not describe how the audion worked.

Triode.pdf is not an RS.

The U.S. Supreme Court in De Forest Radio v GE saw no fundamental difference between the soft and hard vacuum device. Langmuir's purported invention just had a higher vacuum. Higher vacuum made the device more stable and usable at higher plate voltages. With a 20 V plate voltage, an electron may excite a molecule but it will rarely ionize it.

De Forest was interested initially in detectors; he wanted a nonlinear device, but even detectors can have gain. If the audion had no gain, then it would not have an advantage over the Fleming (high vacuum) valve. That De Forest wasn't interested in quasi-linear amplifiers isn't a reason to quash the invention.

De Forest was not a good circuit designer. Although De Forest is credited with DC biasing Fleming's valve to improve performance (maybe he stole the idea from the carborundum detector bias), his audion detector designs did not DC bias the grid but rather DC isolated the grid. See the patent. The benefit of the imperfect vacuum (or leaky capacitors) was setting up a suitable grid bias voltage. De Forest exploited the soft vacuum for that effect. If there were no positive ions and the capacitor was extremely high resistance, then the grid would collect negative charge until it repelled all further electrons from the cathode. De Forest's circuits would stop working when the vacuum got too high. That's a failing of the circuit and not the device. It probably also led De Forest down a false path about how the device worked.

Armstrong's September 1915 IRE (1997 IEEE Classic; also Electrical World 1914) paper on using audions teaches circuits with DC bias on the grid (e.g., figure 20). Armstrong discusses the grid leak problem, and says "This effect is sometimes troublesome in the reception of signals, especially in high vacuum tubes." Armstrong knew of the soft/hard distinction, but the implication is designs could use soft or hard vacuum tubes. By letter in response to De Forest, Armstrong states the audions he used had sufficient vacuum (Langmuir style) to operate by thermionic emission ("that the vacuum of the bulbs was such that only thermionic currents existed"). The exchange between De Forest and Armstrong is illuminating. Armstrong explains that the variations of the soft vacuum audion pointed out by De Forest are due to the gas. However, Armstrong goes on to state that that the audion can be used at the lower end of the plate potentials:

Dr. de Forest speaks of the great differences existing between the wing potential-wing current curves. It will be readily understood by those familiar with the laws of the conduction of electricity through gases that such is bound to be the case where any considerable amount of gas is present in the bulb. The potential at which progressive ionization of the gas begins, is dependent, among other things, on the pressure; and hence the upper parts of the wing potential-wing current curves vary, but the lower parts, the only place where the electron relay can be operated, are invariably of the same general shape. With the modern methods now available, for producing very high vacua, it is a simple matter to construct audions whose characteristics are for all practical purposes identical. With these high vacuum bulbs, the astonishing differences of which Dr. de Forest speaks disappear to an astonishing extent. (Armstrong 1997, pp 695–696)

Armstrong's comments speak to better devices rather than fundamentally different devices. Keep the plate voltage low enough, and ionization is not an issue.

De Forest was also improving other aspects of the audion. I doubt carbon is a good emitter; IIRC, De Forest started using tantalum.

The book Applied Electronics (Wiley, I think 1943; it's buried in the garage right now) discusses the effect of residual gas on the space charge. IIRC, there's also a huge discussion on cathode emission technology. It wants a vacuum of 1.0×10⁻⁹ atm (7.6×10⁻⁷ mmHg). Fleming wanted 0.01×10⁻³ mmHg (1.3×10⁻⁸ atm) (a deeper vacuum than Langmuir). For comparison, mercury at 300 K (reading from a chart and ignoring temperature rise from filament) is 5×10⁻³ mmHg (6.6×10⁻⁶ atm); at 400 K, it is 1 mmHg (0.0013 atm); a heated tube with mercury in it will have a poor vacuum.

Glrx (talk) 05:34, 4 December 2016 (UTC)

It seems to me the article's terminology should follow that found in reliable sources. The triode is still used as an electronic component, so I think the appropriate definition of "triode" should be that found in modern technical sources, which call it an amplifying vacuum tube (there are gas-filled triodes but they are usually called thyratrons). Virtually all the sources I regard as authoritative call the Audion a triode: Okamura, p.19-21, Sarkar, p.101, Wood, p.9, Lee, p.11, Aitken, p.195, Huurdeman, p.226, Heilbron, p.819, Hong, p.x,119,223, (Malanowski, p.50 does not) and most call it a "vacuum tube". To me this makes sense from a "history of science" POV: the crucial innovation which made possible amplification, later triodes, most other vacuum tubes, and the entire field of electronics, was the addition of the grid to the diode valve by De Forest and Lieben. Langmuir's higher vacuum was just a refinement. So the Audion, and probably the Lieben tube, were the "first" triode vacuum tubes. --Chetvorno^TALK 09:49, 4 December 2016 (UTC)

On the Lieben tube: The tube patented by Von Lieben in 1906 was not really a "transmission grid" triode like the Audion, it was more similar to Braun's cathode ray tube ( Sarkar, p.335-336, Nebeker, p.13, Tyne, "The Saga of the Vacuum Tube, Part 8", Radio News, Nov 1943, p.26). The input signal was applied to a deflection coil or plate which deflected the electron beam from the cathode transversely, so more or less of it struck the anode plate. It wasn't until 1910, 4 years after De Forest's invention, that Lieben, Reisz, and Strauss patented a tube that had a "transmission grid" like the Audion, that controlled the current by letting more or less of it through. This probably explains why many sources don't mention Lieben and credit De Forest as the sole inventor of the triode.--Chetvorno^TALK 00:48, 5 December 2016 (UTC)

Agree we should not stray into primary research. We should also not look for "who used a word where" or discount sources because we don't like the title but stick to more detailed description. Wikipedia does have two articles, Triode and Audion, so we are already saying they are two different things. From what I see we seem to have a few different things here: some types of 3 electrode (triode) "soft valve" vacuum tubes, and a specific "hard valve" vacuum tube amplifier called "the Triode". Okamura notes the progress from one to the other and notes the beginning of triodes with the Audion and Lieben valve. Dito with Sarkar. Wood doesn't go into detail with his history or types of devices. Lee notes De Forrest didn't seem to invent anything, one of his tinkerings came out as a triode configuration. Aitken covers more De Forest v. Fleming. Huurdeman - independent invention von Lieben and De Forrest. Heilbron - independent invention von Lieben (and a few others) and De Forrest and distinguishes between the Audion and "hard triodes". Skiadas, Triode was developed in many stages, one being the Audion. Malanowski - Triode is the name for the device developed from the Audion.

I do not think we can call De Forest the "inventor of the Triode" per Okamura, Sarkar, Huurdeman, Heilbron - hard up against WP:YESPOV there. The Triode amplifier?.... definitely not De Forest per almost all of those sources. It would be true to say that the Audion was a triode and "The Triode" amplifier was developed form the Audion. The edits I have made so far follow that and the article where the wording gets dicey is this one, just because this seems to be the article about the hard vacuum Triode amplifier - it states that in the lead sentence but skips inventor(s?) of this device up front. Fountains of Bryn Mawr (talk) 20:39, 10 December 2016 (UTC)

Claim Maxwell investigated the fundamental principle of the triode?

"In 1871 James Clerk Maxwell investigated the principle of grid control, the fundamental principle of the triode." Nether source talks about "grid control", nether states this was the "the fundamental principle of the triode", and one doesn't say it was just Maxwell but also includes Bernhard Riemann. These additions should be reworded/expanded (with hopefully more reliable sources), and should not make synthesized claims. Fountains of Bryn Mawr (talk) 19:49, 23 July 2018 (UTC)

Please, read the actual article and look at control grid. This isn't controversial stuff I'm saying here. I'm sure when Chetvorno comes back on he will tell you that the control grid is indeed the fundamental principle underlying the triode.SQMeaner (talk) 19:55, 23 July 2018 (UTC)

Some references for you listing the grid as the fundamental principle of the triode: http://www.idc-online.com/technical_references/pdfs/electronic_engineering/Triode.pdf, http://www.physics-and-radio-electronics.com/electronic-devices-and-circuits/vacuum-tubes/vacuumtriode.html, www.fishercom.xyz/electromagnetic-waves/the-principles-of-a-triode-amplifier.html.SQMeaner (talk) 20:13, 23 July 2018 (UTC)

The problem is none of the sources make the statement "fundamental principle of the triode" or imply its all just Maxwell, and we do not draw those conclusions ourselves, see WP:STICKTOSOURCE, specifically "Drawing conclusions not evident in the reference is original research". Its your burden to prove otherwise and not just edit war (or claim other editors are not using the talk page [5]). Fountains of Bryn Mawr (talk) 20:47, 23 July 2018 (UTC)

@SQMeaner: I don't see that your statement: "James Clerk Maxwell investigated the principle of grid control" is supported by your sources. All the Harper source says is: "Maxwell published the first study of the effect of a grid of wires on the field between two electrodes". It doesn't say the grid was in a tube, much less that he had in mind a current of charged particles passing through the grid (this was long before the electron was discovered, and scientists didn't even know what was causing those funny lights in Crookes tubes). All the Peto source says is: "The effect of the grid on the electrostatic field was known to scientists from the fundamental works of Maxwell and Riemann." All these amount to is that Maxwell found the electrostatic field of a grid of wires. I can't find any support for your statement in reliable seconary sources like Okamura. As Fountains says, your conclusion is WP:SYNTHESIS, and a false synthesis at that. --Chetvorno^TALK 20:55, 23 July 2018 (UTC)

Please take a look at the following link, where it states 'He (Maxwell) also deduced the shape of the electrostatic field about a wire grid placed between two electrodes'. The fact he used electrodes indicates he was passing a current between a grid and therefore is indeed the inventor of the control grid circa 1870. https://archive.org/stream/HistoryOfWireless/HistoryOfWireless_djvu.txt. I also don't see what that Okamura thing has to do with this conversation. It doesn't even mention who invented the control grid.SQMeaner (talk) 21:06, 23 July 2018 (UTC)

"indicates". It would be possible to draw that conclusion, establish ones self as an expert, have this peer reviewed, have it cited by several secondary works, and then use it in Wikipedia. We can't shortcut that, please read again the policies of the project you are trying to edit. Fountains of Bryn Mawr (talk) 21:14, 23 July 2018 (UTC)

OK, you would prefer I say 'does' instead then? What does it matter? The evidence clearly indicates Maxwell discovered the control grid principle circa 1870 and it would be downright criminal to neglect to mention him in a history of the triode.SQMeaner (talk) 21:16, 23 July 2018 (UTC)

What page? --Chetvorno^TALK 21:18, 23 July 2018 (UTC)

Sorry, I just used Ctrl+F and grid to find that sentence. But having checked through a PDF version it appears to be on page 70. I also found another reference that states that Maxwell's 1871 experiment 'was directly applicable to the audion'. You can find it here: https://books.google.co.uk/books?id=h850HhOi3NQC&pg=PA227&dq=Maxwell+Wire+Grating&hl=en&sa=X&ved=0ahUKEwiszKWVmLbcAhWECuwKHTv2C60Q6AEIPDAD#v=onepage&q=Maxwell%20Wire%20Grating&f=false. I'm sure if someone were to look through Maxwell's treatise on electricity they could find the experiment he conducted and as a matter of fact I have tried myself but the language is too archaic and technical for me, which makes comprehension of his experiments difficult.SQMeaner (talk) 21:21, 23 July 2018 (UTC)

Okay. "He deduced the shape of the electrostatic field of a wire grid placed between two electrodes." in no way indicates that he was "passing a current through a grid". Vacuum tubes were 30 years in the future, and scientists of the time didn't know what electric currents were. If Maxwell had passed some kind of current through his grid and controlled it, the book would certainly say that and all the history books would say the inventor of the triode was Maxwell, not De Forest. It was simply a calculation of the field of some metal pieces in open air, an electrostatics problem. Your huge leap to your conclusion is based on "20-20 hindsight" and an ignorance of the enormous development in physics between 1870 and 1907. As your source says I'm sure Maxwell's calculation was helpful to De Forest when he discovered grid control, but Maxwell didn't have any idea of grid control. --Chetvorno^TALK 22:05, 23 July 2018 (UTC)

Actually, going by my source, he must have had an idea of grid control because he understood that currents could be amplified using the grating. And your claim that he didn't pass a current through the grid seems to be based on absolutely nothing. He used electrodes, as in things you use to pass electric current through. How on earth could he have done anything but pass an electric current through them? And I know you're going to try and use that to claim I'm jumping to conclusions but the fact is this stuff doesn't need to be spelt out and the author probably assumed the reader would understand. To be honest, you're kind of beginning to confuse me and I suspect that's got more to do with the senselessness of your logic than anything else. I would like to get someone involved in this discussion who has some technical knowledge and isn't either you or FoBM as I strongly suspect you are too biased to win over through force of reason alone.SQMeaner (talk) 22:18, 23 July 2018 (UTC)

Where does your source say that he understood that currents could be amplified using the grating? --Chetvorno^TALK 22:29, 23 July 2018 (UTC)

Did you even look at my source? Fine, I'll quote it for you. In the section 'Calculation of Amplification Constant' it says 'An expression for this effect had been derived by Maxwell long before the audion came into existence'.SQMeaner (talk) 22:34, 23 July 2018 (UTC)

I did look at your source. Did you? Your Van Der Bijl source says: "The problem Maxwell set himself was to determine the extent to which a wire grating could protect apparatus enclosed by it from external electrostatic disturbances". Nothing about amplification. Your Harper source writes: "Long before the thermionic valve was invented, Maxwell published the first study of the effect of a grid of wires on the field between two electrodes" The constant $\mu$, now called the "amplification constant" was not called that in Maxwell's time, and he calculated it without any reference to amplification or current between the electrodes. It just expresses the shielding effect of the grid wires on the electrostatic field of the metal plate beyond it. If you look at your Harper source, you will see that

$\mu ={-2\pi d_{gp} \over a\ln {{\big (}{2\sin \pi r_{g} \over a}{\big )}}}$

where

$d_{gp}$ is the distance from the grid wires to the plate

$a$ is the distance between the grid wires

$r_{g}$ is the radius of the grid wires

See? It's just a geometrical factor based on the shape of the grid and spacing. Nothing about current or amplification. Harper is saying that it is now used to calculate the amplification of triodes, but Maxwell just used it to calculate the shielding effect of a grid of wires in electrostatic problems. --Chetvorno^TALK 23:48, 23 July 2018 (UTC)

In other words, he discovered the principle of grid control, even if he didn’t apply it to the same purpose as later inventors. Also, here’s a reference for you stating that Lenard used grid control in his photoelectric experiments: https://books.google.co.uk/books?id=7eUUy8-VvwoC&pg=PA339&lpg=PA339&dq=Lenard+%22Grid+Control%22&source=bl&ots=Jz9GUrORnL&sig=RmykFYONMQHF15wmhqdU3b15VDM&hl=en&sa=X&ved=2ahUKEwiahJXQz7fcAhVBXsAKHd_YDmcQ6AEwAXoECAIQAQ#v=onepage&q=Lenard%20%22Grid%20Control%22&f=false. Also, in your edit you claim that the Der Bijl link ‘explicitly states Maxwell was not studying amplification or grids’. This is news to me, where does it say that?SQMeaner (talk) 11:35, 24 July 2018 (UTC)

Read your Van Der Bijl source closely: "The problem Maxwell set himself was to determine the extent to which a wire grating could protect apparatus enclosed by it from external electrostatic disturbances" Maxwell had no idea about vacuum tubes, amplification, putting a wire screen in a tube, or passing current through it: "grid control". Wire screens were used for a different purpose, electrostatic shielding; preventing electrostatic fields from affecting delicate apparatus. That is the problem Maxwell was working on. --Chetvorno^TALK 15:26, 24 July 2018 (UTC)

You didn't tell me to read my source closely. You said it explicitly stated Maxwell was not studying amplification or grids and you have not shown where it says this in my Der Bijl source. Also, a grid can still be used in an electronic component even if it's not necessarily in a vacuum tube or even a tube. Otherwise, transistors would be massive. And if what Maxwell was studying had nothing to do with amplification why does Der Bijl refer to it as an 'amplification constant'? Maxwell may have been working to a different end than electronic amplification but it seems pretty clear to me he still discovered the principle of grid control in doing so. I'm also interested to hear what you have to say about that last source I posted to do with Lenard.SQMeaner (talk) 15:56, 24 July 2018 (UTC)

Van Der Bijl calls it an "amplification constant" because he is writing in 1920 and by that time it was used to calculate amplification. It would be fascinating if your idea was true, and I can see how much you want it to be true, but if you read the history critically you will see there is no support for it. As User:Fountains of Bryn Mawr and User:Glrx can tell you, the concept of controlling a current of charged particles by passing it through a grid was a very difficult idea for scientists of the time to understand, and even 40 years after Maxwell Lee De Forest who invented the grid triode did not really "invent" it, he just stumbled on amplification while putting electrodes of different shapes in tubes, and even after it was invented he didn't really understand how it worked. --Chetvorno^TALK 16:17, 24 July 2018 (UTC)

I don't understand how you can literally admit that Maxwell's equation was used for amplification and still hold on to the claim that he didn't discover grid control. I'm really not sure if this argument is worth pursuing at this point because you absolutely refuse to consider the idea that Maxwell invented grid control regardless of the volumes of evidence I've provided indicating he did. Again, I really would appreciate it if we could bring in someone who really knows what they're talking about and isn't you or FoBM or that other guy you mentioned as the level of bias you are displaying is absurd. Finally, I'm still waiting to hear what you have to say with regards to Lenard and grid control, who also appears to have discovered it before De Forest.SQMeaner (talk) 16:23, 24 July 2018 (UTC)

Well, you've convinced me on Lenard's use of grids, there are multiple sources which support that. If you want to put it in the article I'll support you. But you've got to be careful how you write it, not give it WP:undue weight. It is not a very WP:notable fact, there is no indication Lenard inspired anyone else or used it for amplification. The sources don't give it more than a single sentence so I think that is all it merits in this article. --Chetvorno^TALK 16:49, 24 July 2018 (UTC)

Very well. I suppose we will have to agree to disagree on whether or not Maxwell discovered grid control but at least Lenard is properly mentioned. I don't think I could write a suitable history section mentioning Lenard that would meet with your approval and as I'm quickly growing tired of this argument I will leave it in your hands.SQMeaner (talk) 16:54, 24 July 2018 (UTC)

e/c

Displacement current is between two electrodes but does not involve charges moving across a gap. Capacitors have currents between two electrodes without electrons traveling from one electrode to the other. Maxwell can investigate a grid attenuating displacement current flow to one of the electrodes. If the electrodes are 1 m apart, then a grid wire spacing of 1 m will let most of the displacement current through. If the wires are spaced 10 cm, less will get through. At 1 cm spacing, very little will get through. That attenuation can be viewed a gain/amplification. Varying the potentials on the grid and two electrodes will also affect the fields. Maxwell can know all that, but did he consider packets of charge going from one electrode through the grid to the other electrode? We'd need a clear source for that.

The invention of the triode is about much more than the grid; a triode needs a vacuum to allow electrons to move unimpeded and avoid ionization, it needs thermionic emission to source electrons; it needs a space charge around the cathode for the grid to control, it needs a grid potential that mostly repels and does not suck up the space charge, and it needs high potentials on the plate to sweep the electrons that pass the grid.

Better sources are needed or else it is synthesis. Glrx (talk) 17:47, 24 July 2018 (UTC)

OK seeing as Chetvorno doesn’t seem to want to do the edit himself I took it into my own hands and did it myself. A single sentence, as agreed upon here.SQMeaner (talk) 13:54, 25 July 2018 (UTC)

Looks good. --Chetvorno^TALK 17:16, 25 July 2018 (UTC)

life

The article seems to say that high power tubes have longer life than low powered ones. That seems unusual. Gah4 (talk) 02:13, 12 August 2020 (UTC)

I added those figures. I got them from a book but didn't source it and now I can't remember which book. I'll keep looking. I think the reason is the thoriated tungsten filaments used in power tubes have a longer lifetime than the coated cathodes of small signal tubes, because the cathode coating is eventually eroded by ion bombardment. --Chetvorno^TALK 16:01, 12 August 2020 (UTC)

The high power tubes should have more electron current, so also more ion current. Some tubes were used in continuously powered systems with mostly no current. But yes, it depends on how they are built. A year is about 8000 hours, so one should last at least that long with low current. But otherwise, yes, it depends on what WP:RSs say. Gah4 (talk) 17:36, 12 August 2020 (UTC)

This one says 3000 to 5000 hours for the average tube, and 50000 hours for lightly loaded tubes. Not the most useful description, though. Gah4 (talk) 18:45, 12 August 2020 (UTC)

The greater ion current is why thoriated tungsten filaments are used in power tubes instead of coated cathodes. The thorium is embedded in the tungsten and continuously diffuses to the surface, so as the emission layer is removed by ion bombardment it is continually replaced. Sources say thoriated tungsten tubes last a lot longer than coated cathode tubes. Part of the difference is that low power tubes in consumer electronics were continually turned on and off, the thermal cycling shortened the lifetime, while the greater cost of power transmitting tubes motivated transmitter designers to preserve the filament, by operating it below rated current and keeping it on ("black heat") while the transmitter is off to keep it at a constant temperature. These two articles [6] and [7] say coated cathode tubes have lifetimes of 1,500-2,000 hours, while thoriated filament types last 4,000-10,000 hours. Yes, the life of both types can be extended by various measures. --Chetvorno^TALK 14:25, 13 August 2020 (UTC)

current through the tube from cathode to anode

The article says: current through the tube from cathode to anode. However, current it, by definition, positive so current is anode to cathode. Electron flow is cathode to anode. Gah4 (talk) 18:22, 12 August 2020 (UTC)

Thanks for catching that! I corrected it. --Chetvorno^TALK 00:21, 14 August 2020 (UTC)