Talk:Vacuum tube/Archive 3

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AC/DC

Well I took a quick look (but very quick) at the history of the AC/DC page! (But not the talk pages) First, Wtshymanski is VERY wrong about the safety issue! Doubling of current greatly increases the chance of ventricular fibrillation, the most common cause of death from shocks. I sort of thought this was common knowledge and I'm willing to bet he's never gotten bit by 220. Nor have I since living in Europe, but that's because the plugs are made much safer, whereas with the US plugs you can easily get a shock (not fatal but just between your fingers) if you're careless holding the plug. Plus the power cords are made safer (I assume according to regulation) compared to the cheap "zip cord" widely used in the US. I got my first shock when I was about 5 years old just unplugging something (like my mother told me not to) and a friend's dog got shocked very badly after chewing through a power cord. So here the power cords need less copper and more insulation. And that's interesting (and telling) what I read there about the UK requiring power tools to run on 120, for this very reason (so you have to buy your own transformer then?)!

I'm not sure if there were 120v TV's which ran tubes on 160v directly rectified, but THOUGHT so. And more so that transistorized sets did so, with the low voltages generated through extra windings on the flyback transformer and a HV transistor running it (or possibly a tube??). I don't have exact info nor is my memory too great. And there MAY have been ones using voltage doublers to get 300v just like the 220v sets. Of course those wouldn't have been AC/DC but that wasn't the issue. In fact, I don't know who ever needed one to run on DC; I never knew of 120v DC being supplied anywhere in the US (or why!). Or how they knew which direction to plug it in so it actually worked. And whether the loss of 30% of the high voltage would matter (presumably not with the radios). I do not remember AC/DC ever being labelled on a TV, but it wasn't really a selling point for those radios either, just an extra bullet point on the advertising. So as far as the article goes, I don't know, don't really care, but saying NOTHING about the difference between 120 and 240 is less likely to be mistaken than the distinction you added (based on what you had been told). Especially if there were indeed ones that worked using voltage doublers (not AC/DC then, but that wasn't the issue). Cheers, Interferometrist (talk) 18:30, 26 April 2011 (UTC)

"...the UK requiring power tools to run on 120, for this very reason (so you have to buy your own transformer then?)!" That's only for professional use, typically on building sites, where you can easily cut into a cable. Everything operated by mains in a home is nominally 230vac (i.e., 220-240).

If anyone considers that I've written anything wrong (the bit about no 120VAC AC/DC TV is certainly unreferenced), please feel free to delete it. I may have got some detail wrong; the discussion on the AC/DC article was AFAIR about true AC/DC sets, not just derivation of part of the supply from the mains. Pol098 (talk) 19:04, 26 April 2011 (UTC)

The risk of death by electrocution is not purely proportional to voltage. While current rises with voltage and increases risk, so also does the associated gross muscle spasm. This produces the paradoxical result that for voltages above 240 volts the risk starts to reduce again due to the larger spasm being more likely to break the connection. For very high voltages, for example 6kV and above, the current may be so large as to cause gross cardiac clamping rather than fibrillation, an effect similar to a defibrillator, and the victim survive (although serious burns may result). Post-war 32 volt power tools and stepdown transformers were in use on Australian building sites and industry. 32 volts was also used in some American dairy farms but fatalities were reported none the less. Genuine "transformerless" AC/DC radios and televisions were still all too horribly common in the UK in the late '60's (where I started teching), as were suitable isolation transformers for bench testing. Roly Roper ozvalveamps.org

I once compared electrocution fatalities in Ontario vs. the UK - I can't recall what the actual numbers were but I seem to recall UK had fewer residential 'wall socket' electrocutions per capita, but Ontario had fewer per terawatt-hour of residential consumption. I doubt there's a significant documented difference in the safety risks, we have quite enough deaths at 120 V in spite of Lord Kelvin's assumption that voltages around 100 were survivable.

DC was once widely used as a distribution voltage, and persisted even up to WWII - ironically, for example, the hotel that Nicola Tesla died in was famous for its elaborate DC electrical system. I don't believe "television" and "wall socket DC in the home" overlapped considerably, all the 120 V tube TV sets I ever tore down had power transformers in them, even if the tube filaments were series connected. I recall there were very many tube-type clock-radio combinations that could not run on DC because of the clock motor, but otherwise had the standard AC/DC "All-American Five" tube line-up. I wonder why 240 V tube sets just didn't up the heater voltage to, say, 45-50 volts per tube; there must be a reason why high heater voltages were unused, all the 240 V set schematics I've seen have extra dropping resistors. A voltage doubler off 120 V AC would have been an expensive power supply, it was probably cheaper to put in the power transformer than all the extra rectifier tubes and filter capacitors that would have been needed; it would likely have used less power, too. --Wtshymanski (talk) 19:37, 26 April 2011 (UTC)

This, from a link I added to the AC/DC article, might still be of interest (normal mains voltage was 240V, and the article says that DC was still widely used): "The first set capable of operation from D.C. supplies - but not by design!

Whilst Pye's 1946 model B16T established Pye's technical lead in domestic television, far more technically important was their B18T model released in 1948. Up to this point all televisions required an A.C. mains supply since a transformer was required not only to provide the very high EHT voltage required by the CRT but also to provide a supply high enough to enable the scanning coils to be driven quickly enough using the valves then available (valves specifically designed for TV use were yet to appear in any number). The mains transformer was necessarily large and expensive, and had to be carefully positioned such that its magnetic field did not interfere with the scanning of the CRT. The B18T's solution was three fold; first the EHT was generated by rectifying the high voltage pulses generated across the (line) scan coils. Secondly, energy recovered from the scan coils during this flyback was used to "boost" the HT supply used to scan the coils. Finally, all of the valve heaters had to be connected in series, a challenge given that specialised valves with the necessary heater-cathode insulation had yet to be introduced

There was little room to accommodate any reduced mains voltages and indeed operation at a reduced 190v-220v AC (supported by almost all other manufacturer's sets) required the addition of an auto-transformer costing an additional £1 5s.

Thus the B18T was the first set that no longer required a mains transformer. This had an accidental side effect - it became the first set that could also operate directly from DC mains (still in use by many households) although this had not been the original design intention and indeed the manufactures initially never advertised the set as anything other than for AC supplies only. Pye did, however, subsequently make some very minor modifications to better suit D.C. operation.

The B18T's design features were not original - the idea of rectifying the line scan voltages to develop EHT had been developed in Germany immediately prior to World War II, and the basic principle of recovering energy from the scan coils had been covered in a British patent as long ago as 1932 (albeit using a different circuit). But nevertheless, it was still Pye who produced the first commercial implementation of these ideas.

Within only a few years almost every manufacturer had adopted the same techniques, which would continue to be used for many decades to follow. The method of EHT generation was not however without its difficulties due to the extreme transformer insulation requirements of the EHT winding of the line output transformer. Indeed, at the start of the 50's some set manufacturers were producing as many as three times as many line output transformers as they did television sets ! "

Wtshymanski: "I wonder why 240 V tube sets just didn't up the heater voltage to, say, 45-50 volts per tube; there must be a reason why high heater voltages were unused, all the 240 V set schematics I've seen have extra dropping resistors." I don't know whether some sets could omit the dropping resistor. The best type of set to look at would be an AC/DC colour dual-standard (405 and 625 line) UK set, probably the most complex sets ever made (if they were made!), and would have the largest valve complement. Standard valve types for series connection were the U series, 100mA heater current,for AC/DC radios, and the P series (PL33 etc.), 300mA, for television use. It makes sense to provide valves which require a bit less voltage than is available; it seems wiser to drop a few volts than to risk designing a more complex circuit which requires a total of 260V heater voltage with standard components! (If this were an article you'd be justified in raising the OR and speculation flags.) Pol098 (talk) 20:40, 26 April 2011 (UTC)

But were there any 240 V "wall socket" DC distribution systems? North American DC systems were around 120 V DC. I would think that interupting 240 VDC to a receiver requires more of the switch than 240 V AC - certainly looking at any manufactuter's catalog for pilot devices such as pushbuttons and limit switches shows that the same contacts that may be rated for a coule of amperes at 120 VAC or 240 VAC might only break a few tenths of an amp on a 240 V DC system. --Wtshymanski (talk) 20:59, 26 April 2011 (UTC)

Not 240 volt DC in the UK, but close. DC distribution was surprisingly standardised where it was implemented. Although some systems did differ, most DC was generated and distributed at 200 volts. Not many people realise that the last DC generating and distrubution scheme was decommissioned as late as 1981. Bankside Power Station generated 200 volts DC solely to operate the antiquated (circa 1920) hot metal type machines still in use in London's Fleet Street newspaper printing works. After its decommissioning, the DC supply was obtained from locally installed rectifiers operated from the standard AC supply.

UK manufactured TV sets were officially rated to operate off of both AC and DC supplies. The contacts in the mains switch would thus have been able to break the full load current on a DC system. I can recall that the switches (usually combined with the volume control) on all the TVs that I used and repaired operated with a good healthy 'click' from the spring mechanism of the contacts. 109.153.242.10 (talk) 17:39, 5 January 2012 (UTC)

Not sure I understand. I don't think domestic electricity was supplied other than through wall sockets; some sockets were rated at well over 10A (15A? 13A now). (Big appliances - cookers - are sometimes connected directly to the mains without plug.) I believe that DC was discontinued everywhere in 1946. I don't know if this is true, or how it ties in with TV. I don't know about switching DC, may depend on inductance of load, which wouldn't apply to electronics. Maybe a snubber network would be needed? Pol098 (talk) 21:44, 26 April 2011 (UTC)

I would be interested if anyone could find a description of a distribution system that used 230-240 VDC to wall sockets - I don't think this was ever used, because of the switching problem, and so I don't think there could ever have been such as thing as an "AC/DC" 240 Volt TV set. --Wtshymanski (talk) 02:56, 27 April 2011 (UTC)

I assume that you are not on the European side of the big pond. All early distribution systems in Europe were DC (as in the US - and probably elsewhere). In the UK they were more or less 200 volts. Some systems obviously did vary, but 200 volts was surprisingly standard. Some areas did use lower voltages (down to around 120 volts), but I am not aware of any higher voltage systems (where the current is generated at the distribution voltage - ignoring traction systems, of course). All UK sold TV sets that were built to the AC/DC design were designed and rated to operate from both AC and DC supplies as these sets were first manufactured when DC supplies were still prevalent. The mains switches were designed to break the DC current courtesy of a spring 'snap action' mechanism. Even many colour Televisions when they were first introduced (around 1966) were still of the AC/DC design, and my service manual for the Philips 25 inch set that my parents bought in 1969 tells me that the set is rated to run from 200 to 250 volts AC or DC. 109.153.242.10 (talk) 17:39, 5 January 2012 (UTC)

Confirmed: UK (and indeed European) TV sets were designed to operate from both AC and DC supplies right up to when switch mode power supplies were introduced. I am not that well versed with US TV sets, but I assume that they would have had to include a voltage doubling circuit to provide enough HT supply (B+ for our American friends) for circuits such as the scan generators to operate properly. The voltage doubler would not, of course, operate from a DC supply so this may explain why US TV sets were not specified to tun from DC. DieSwartzPunkt (talk) 15:00, 6 January 2012 (UTC)

Switching DC poses special problems not encountered on AC. Generally if you separate two contacts that are carrying direct current at any appreciable voltage over (around) 30-40 volts, the current will try to continue to flow across the separating contacts in the form of an arc. At 200 volts (the more or less standard UK DC distibution voltage) the contacts have to separate a considerable distance before the arc ceases. The distance can be shortened if the contacts are separated rapidly. With normally encountered alternating currents, the arc automatically extinguishes as the current falls to zero at the end of the half cycle. Thus when switching AC, the switch conacts can separate slowly and need only part a short distance (hence the use of microswitches). With DC the contacts have to be separated rapidly (usually with a spring mechanism) and through an appreciable distance. 109.153.242.10 (talk) 17:39, 5 January 2012 (UTC)

Some comments specifically for Wtshymanski, as well as factual information, follow. If I may be mildly critical (before going on yet another search to back up what I well know from prior knowledge to be true), in this and previous discussions you tend to have too much confidence in your own ideas of what is possible based on armchair thinking, which you value over and above other people's actual experience and knowledge; you should have tried to check this possibility yourself before sending others to do it. This isn't intended as an attack or dispute; some of the criticisms you made in discussions we had re the AC/DC article, although wrong, did force me to find proper supporting evidence, which improves articles. Anyway "Direct current supply is given throughout the borough at pressures of 220 and 440 volts for lighting and power purposes". 1914. This doesn't affect what's said in any article and I'm not going to do more searching; I do recommend that you look into this yourself if you find the above quote unsatisfactory. A good starting search string is "uk dc mains electricity history". remember that you ae seeking fo use of DC somewhere; use of AC elsewhere is no disproof: voltage, frequency, and AC or DC varied from one locality to another.

Wtshymanski: "I don't think there could ever have been such as thing as an "AC/DC" 240 Volt TV set". Again armchair thinking which doesn't even take any account of text which I've carefully already quoted in full here. I repeat from what I quoted above: "Thus the B18T was the first set that no longer required a mains transformer. This had an accidental side effect - it became the first set that could also operate directly from DC mains (still in use by many households)". Again, if you dispute this please first you find evidence that it is not true.

In spite of what I said I will add one more piece of information, easily available to you, which you should have checked: this article mentions casually in passing TVs with AC/DC chassis. Maybe not enough for a court of law, but another piece of rather clear supporting evidence. We held this discussion over AC/DC TV a long time ago, and I referenced there all the clear evidence I'm quoting here.Pol098 (talk) 06:16, 27 April 2011 (UTC)

Having spent (wasted) a fair amount of time, I'd summarise previous arguments given against AC/DC distribution and TV: "I think, from a quick glance at specifications of some switches, that 240VDC power distribution was not feasible and that 240VDC TV operation was not possible. This knowledge enables me to say that statements by people who claim to know, and references contradicting this, are false unless proven true (although I may dispute all further evidence if it contradicts my beliefs)." I'm being fairly blunt, but I do feel that this is a fairly accurate parody of previous discussion, and has led me to spend too much time looking up things supporting what I well know to be true, much of which I had already referenced well in another article, for a Talk, rather than article, page. Pol098 (talk) 06:39, 27 April 2011 (UTC)

200 volt DC distribution was common in the UK up to the late 1940's and diminished thereafter over a decade or three (the last 200 volt DC power station being decommissioned as late as 1981. UK TV sets were indeed manufactured to operate from AC or DC supplies, and one of the positions on the voltage range changer (200-210 volts) would only have been of use with a DC supply as the lowest AC voltage known to have been used for distribution in the UK was 230 volts (arguments about continental supplies are irrelevant as UK TVs would not receive anything there). The mains switch (part of the volume control) on all these sets was fitted with a spring mechanism to separate the contacts with a firm 'snap' for operation on DC. This was true of all the AC/DC type TV sets that I repaired in the 1970's - still a common design at the time.

Most people don't know this: but computer power supplies and indeed any flyback type switch mode power supply will operate quite happily from a DC supply - but only if they do not include a voltage doubler as many US supplies do. They do prefer around 25% more volts on DC. Any mains switch included is generally of a AC only design though. 109.153.242.10 (talk) 17:39, 5 January 2012 (UTC)

It's called "research" and is the foundation of an encyclopedia. I inquired if you had citations for some of the statements and you've supplied them. We're not allowed on WIkipedia to say things that we just know to be true, we're required to provide citations for them. It's a pity you consider this time wasted, as citations strengthen the credibility of the article. --Wtshymanski (talk) 13:48, 27 April 2011 (UTC)

In general I agree that references are needed, which is why I said being challenged about AC/DC TVs in the AC/DC article was legitimate and prompted me to add references which improved the article. In this particular case we're talking about a talk page, not an article. One of the issues questioned had already been addressed by me in this same section; I merely copied the sentence again in response. Another reference I had added to AC/DC (already mentioned in this discussion) when the issue was last discussed there. The references clearly implied that TVs operated off DC mains, which would have to be in use for this to mean anything. The reason for questioning these points was not any information tending to contradict the references, but an impression that the direct quote already given from a reference ("Thus the B18T was the first set that no longer required a mains transformer. This had an accidental side effect - it became the first set that could also operate directly from DC mains (still in use by many households)" could not be so. So I felt that in this case the additional research was not warranted. Pol098 (talk) 14:31, 27 April 2011 (UTC)

"I think, from a quick glance at specifications of some switches, that 240VDC power distribution was *not feasible* and that 240VDC TV operation was *not possible*." Sorry, but this is simply wrong on both counts; switching DC isn't impossible, just slightly more difficult, for current example Melbourne trains run on 1500VDC and trams on 600VDC (http://en.wikipedia.org/wiki/Port_Melbourne_railway_line). Large DC contactors (switches) are made snap-action and may include "arc-chutes" and magnetic arc snuffers. In fact historic domestic switches where spring-loaded overlocking with double break contacts and were very well suited to DC operation, unlike modern "economical" lever action types. Toggle switches rated at 240VAC were widely used in Australian valve guitar amplifiers in the 60's and 70's to switch HT up to 600VDC/250mA with no ill effects (Strauss, Eminar, Maton, &c&c). Something more than a quick glance would have produced many dataseets for switches and relays that carry contact ratings for both AC and DC, the DC current being typically one-fifth of the AC current rating - two quick examples; switch (http://www.jaycar.com.au/productView.asp?ID=ST0335), relay (http://www.jaycar.com.au/products_uploaded/SY-4060.pdf). I have personal experience bench repairing genuine 240V AC/DC TV's in the UK. If they can't be cited (apart from e.g. http://www.bvws.org.uk/405alive/tech/safety.html) that is the shortcoming of the sources, not because they didn't exist. Two other mentions of UK DC mains systems, implicitly around 220-240V, http://www.laurence-scott.com/aboutlse/history.shtml and http://www.parliament.uk/documents/post/e5.pdf. Roly Roper ozvalveamps.org — Preceding unsigned comment added by 114.74.245.182 (talk) 13:27, 16 February 2012 (UTC)

This issue is of so little importance to me I don't even know why I'm bothering to type, though I'll remember Wtshymanski's caution about switches next time I use one for a large DC current. However I did run across this section which was clearly referring to 120 volt TV's: All American Five#Effect on television design. It doesn't quite say that the B+ was from rectifying the mains, but sounds like it. (I was even more surprised to read in that article that these radios could be run on only 32vdc power if the heaters were rearranged! That seems to contradict the idea that tubes really needed such a large voltage to work at all. Perhaps they only did to achieve their full performance, which of course they tried to get out of every precious tube in a circuit.)

And again on the safety issue of 120 vs. 240. The statistics on the shocking death rates (sorry!) don't tell the story because Europe has safer electrical plugs/sockets, power cords, and power boxes (you can hardly ever get to an exposed conductor). And I assume that is for the very reason of the increased lethality of 240. Actually doing tests on humans would be slightly unethical so I don't think you'll find such studies, but I believe their figures are extrapolated from animal tests (which also sound unethical if the animals were similar enough to humans....) and I recall that 100ma AC for 1 second across the body (arm to arm) was considered likely to cause ventricular fibrillation (the WP article says 60mA). So to answer the question you'd have to plot a histogram of all shocks from 120v in terms of their current, and consider that the ones over 100mA were fatal. Then you can see how many more shocks there were between 50 and 100mA which weren't fatal but WOULD HAVE BEEN if the voltage had been doubled. That's the difference, and would probably have increased the number of fatalities by well more than double. Interferometrist (talk) 13:56, 27 April 2011 (UTC)

If all you had was a 32 V DC farm lighting plant, you were happy to get any kind of radio at all. The All-American five article discusses this at length; if a standard 120-volt design was field-modified for 32 V service, the output was liable to be quite low at 32V, but farm living rooms in those days were quiet places, and it was better than using a headphones and a crystal set. There were two kinds of purpose-built, more explensive, receivers - one style used a push-pull arrangemnt of the output tubes to get more power with limited B+, and the other style used a vibrator power supply to step up 32 V to a more convenient level. This was also common in mobile tube-based equipment, which could run the filaments on the 6 V or 12 V cranking batery supply but needed more volts for tube plates.

Switching DC is hard; that's the biggest reason the 42-volt electrical system hasn't swept the auto industry, and why HVDC systems tend to be point-to-point and not multiply tapped. You can get automotive toggle switches rated for 10 A quite cheaply, but they are also rated only 12 V DC; you're not going to get a 10 A rated switch at 240 V DC in a hang-card at the hardware store.

I don't know how strict product testing was in the days of DC mains; by modern standards you'd have to do a lot of evaluation to make sure the product performed as safely on a DC supply as on AC. Perhaps switches were more rugged in those days. --Wtshymanski (talk) 15:50, 27 April 2011 (UTC)

Ah yes, I remember: the DC draws an arc which AC would interrupt 100 times a second while the contacts are being pulled apart. And yes, I even remember "vibrators" used in car radios, which seems so hard to believe nowadays!

Through this discussion I've also come to realize that 80 or 90% of modern household appliances would work just fine (neglecting the power switches) if someone switched your mains to DC while you were sleeping! All the lights and electric heating of course. And then all the computers and gadgets which say "90 - 240volts" which directly rectify the AC (or pass DC) to run switching supplies (not requiring vibrators ;-) . Even a lot of the plug-in "transformers" now work that way. Clocks using sync. motors are almost non-existent. You'd only have big problems with anything using an induction motor. Hell, I'm wondering if they shouldn't change. Nowadays a DC-DC converter at a substation would probably be cheaper than a huge transformer, no? (And as efficient?). Power switches could probably be made for 50 cents using a MOSFET to do the actual switching instead of arcing contacts. Gee, I think I just found a new cause to promote..... ;-) - Interferometrist (talk) 16:14, 27 April 2011 (UTC)

I'm rather fond of the induction motors in my house. My basement would flood, my food would spoil, ventilation would stop, the furnace and AC would quit (OK, maybe the furnace blower now works on DC but I know it's got transformers in the controls), and many of the wall warts would pop. The microwave oven wouldn't rotate; even the wall ovens wouldn't convect, and the touch controls wouldn't work. All my low-voltage halogen lamps would pop. CFLs in 120-volt coutries rely on a voltage doubler in the input stage, as do many 120 V computer power supplies. The LED lights under the counters might run on 12 VDC, but the power supply isn't rated for DC input. But in the flooded, smelly, dark, smoking ruins of my suddenly DC powered home, I could charge the battery on the netbook. And I think my pistol drill and saw still have universal motors, though they wouldn't be variable speed any more and the switches would probably arc down after a few tries. --Wtshymanski (talk) 16:45, 27 April 2011 (UTC)

Ok, ok, I won't switch it while you;re sleeping. You'll get a full month to convert ;-) -Interferometrist (talk) 16:50, 27 April 2011 (UTC)

Why would your low voltage halogens 'pop'? Being filament bulbs they operate equally well from DC as AC. The only problem might be the voltage converter, except that most of the electronic type are of a swtich mode type design that will, in fact, run from DC (given that the input circuit is a rectifier followed by a capacitor). 109.153.242.10 (talk) 17:39, 5 January 2012 (UTC)

While it is quite rare there are circuits around for low level signal applications using a 12AX7 with the same 12.6 volt supply used for both heater and anode HT. Many household appliances such as vacuume cleaners, blenders, and electric drills use series-wound "universal" motors which will happily run (in the same direction) off AC or DC of either polarity. For DC-DC conversion you have basically two choices, a rotary converter - a DC motor driving a DC generator, or a switch mode which turns DC into high frequency AC, transforms it, then rectifies back to DC. This has to compete with existing substaion transformers which are between 95% and 98% efficient, and robust against gross over-load currents and gross over-voltages such as lightning. Such a solid state system is being used to link Victoria and Tasmania under Bass Strait but even under in this controlled situation has reliability problems, so the solid-state local sub-station is a way off yet. Roly Roper ozvalveamps.org — Preceding unsigned comment added by 114.74.245.182 (talk) 14:04, 16 February 2012 (UTC)

AC Power

First, thanks for a very interesting article.

I just wanted to point an editor to a confusing section which may be just a copy & paste error. Under AC Power http://en.wikipedia.org/wiki/Vacuum_tube#AC_power the last paragraph seems to jump from talking about cheater cords to the tube compliment of AM radios.

This would come disconnected whenever the radio was opened (for instance, to test and replace the tubes) preventing such a shock hazard. (Technicians and tinkerers routinely bypassed this by using a separate cord, known colloquially as a "cheater cord" or "widowmaker.") Many US consumer AM radio manufacturers of the era used a virtually identical circuit with the tube complement of 12BA6, 12BE6, 12AV6, 35W4, and 50C5, giving these radios the nickname All American Five or simply "Five Tube Radio." Although millions of such receivers were produced, they have now become collector's items.

Alfredpr (talk) 08:42, 2 June 2011 (UTC)

Re interlocked backs, none of the old 'universal' mains connected chassis sets I've worked on had any such interlock. Tabby (talk) 17:19, 18 June 2011 (UTC)

Well, they'd hardly be "new" sets, though I suppose they were new once. Every 5-tube radio I ever poked around in, and every tube TV, had an interlock like this. I even had saved an old line cord to use as my very own "widowmaker"; not the main risk given my age at the time. What part of the world are you in? Maybe the practice there is different from what it was here in the Great White North. --Wtshymanski (talk) 17:30, 18 June 2011 (UTC)

I believe that this arrangement was probably a feature of US produced radio sets. I never encountered such an arrangement on UK manufactured AC/DC design sets. 109.153.242.10 (talk) 17:34, 7 January 2012 (UTC)

Apparently very common in the US, as a (retired) tech I've never seen a mains interlocked back in the UK or Australia. Roly Roper ozvalveamps.org — Preceding unsigned comment added by 114.74.146.155 (talk) 14:17, 16 February 2012 (UTC)

Terminology

Can I just ask the obvious, why is the title of this article "Vacuum Tube"? Article titles and terminology used in subject matter on the Englsh Wikipedia must be a reflection of the greater majority. The term Valve is more widespread, it is used exclusively to tube in Australia, New Zealand, the UK and many other European Nations, therefore the title of this article should be amended to Vacuum Valve. Subsequent lead paragraph should reflect the usage of the alternative North American terminology, not the other way round. Nick carson (talk) 07:23, 30 June 2009 (UTC)

Is this really important? When I'm reading some UK publication it takes about 50 milliseconds to remember a "flat" is an "apartment" and a "lorry" is a "truck" and then I don't think about it any more. I admit it's somewhat more of a change than "color/colour" which seems to trouble some editors as well, but does anyone other than a Wikinitpicker actually *care* about this? Let's fix all the other problems of the encyclopedia before we standardize all the articles on one or the other variant of English. Please don't move the article for this reason alone. --Wtshymanski (talk) 03:46, 28 August 2009 (UTC)

FWIW, the original correct technical term for the device is not 'Vacuum Valve' but Thermionic Valve - the device works by thermionic emission (heat) which is where the term comes from, and, unlike a two-terminal diode, has three terminals and operates as a valve, the current on one terminal (grid) being used to control the (usually larger) current going through the other two, the anode and cathode. —Preceding unsigned comment added by 86.112.75.181 (talk) 20:19, 27 November 2010 (UTC)

But "Vacuum tube" does encompass tube rectifiers (diodes). So I guess an article on "Valves" would have to exclude discussion of tube rectifiers? Hunh!

I would argue that "Electron tube" or "Electronic tube" would be a better article name than either "Vacuum tube" or "Valve". A "vacuum tube" might be any old tube with a vacuum in it, and similarly "valve" could refer to something having to do with plumbing. And conversely, there are electronic tubes that are gas-filled, so calling them "vacuum tubes" is obviously not universally correct. Jeh (talk) 21:19, 30 January 2012 (UTC)

To challenge the original point, I'm Australian and have for my entire life called them "tubes". As a result my "valve" amplifier uses "vacuum tubes". Inconsistent yes, but hey, Americans drive on a parkway and park in a driveway. Americans make "tube" amps, and the British make "valve" amps, but my research so far indicates all of them are built with "vacuum tubes". (Exceptions welcome). As far as the second point, the term "vacuum tube" is universal in the music industry, but that doesn't mean it's universal elsewhere. Now WP:COMMON states that "Wikipedia does not necessarily use the subject's "official" name as an article title; it prefers to use the name that is most frequently used to refer to the subject in English-language reliable sources.". Hence if 'vacuum tube' is not the common name within the wider world, then we should at least explore the idea of a name change. Manning (talk) 22:22, 30 January 2012 (UTC)

The term "tube" is a fairly new adoption in Australia as a scan of back copies of "Radio, Television & Hobbies" and "Electronics Australia" to the end of the valve era will confirm. Even today while guitarists use the English derived "valve" and US "tube" interchangably, they almost always call them "valve amps" as opposed to "tube amps". The 1961 UK Mullard Maintenance Manual introduction calls them "valves" with the notable exception of CRT's which are called "picture tubes". In Nov 2003 "Silicon Chip" published "The project we swore we'd never do... A Valve Preamp" (front page banner) and titled "A 12AX7 valve audio preamplifier". Roly Roper ozvalveamps.org — Preceding unsigned comment added by 114.74.245.182 (talk) 08:08, 16 February 2012 (UTC)

A fair amount of wasted effort is spent by Wiki editors correcting articles to one form of English or another; a general guideline is that whoever writes the article first gets to decide whether to use British or American English. So, it's "Vacuum tube" and it's likely to stay that way. Since that's the case (lol), I'll introduce the non-politically correct opinion that "vacuum tube" is far more explanatory to a casual reader than "valve". A teen reader anywhere in English speaking countries who watches science fiction is liable to guess without ado what a "vacuum tube" is, without even looking up a definition. "Valve", however is an term that has inherent meaning only if a reader already understands something about electronics. Also, searching in Wikipedia on "valve" goes directly to an article commencing with a picture of water valves. So, by Wiki policy and for the sake of reader convenience, the article is better titled as it is: Vacuum tube. — Preceding unsigned comment added by 76.102.1.193 (talk) 08:53, 8 April 2012 (UTC)

Weasel word tagging

To the IP who insists on adding the "weasel word" tag to the word "musician". Stating that many "musicians" prefer the tube sound does not require elaboration, the entire musical amplification industry is organized around the tube/solid state divide. Hence it is patently obvious and does not require referencing. Please explain your reasons for using this tag if you want, otherwise stop adding it to the article. Manning (talk) 22:04, 24 January 2012 (UTC)

Wikipedia requires citation for all content. If it isn't sourced it can be challenged and indeed deleted. It's not the musician that is causing the problem, it is the phrase "Many audiophiles, audio engineers, and musicians ...". It is the word 'many' that is the weasel word, and it needs to be specified who these people are. Just saying 'many' without elaboration is too vague for an encyclopeadia. As for you claim that it is patently obvious that these people prefer tube sound - well, it still doesn't matter how obvious it is (and it isn't in this case), it still requires verifiable sources to support it (see WP:VERIFY).109.153.242.10 (talk) 13:39, 26 January 2012 (UTC)

I love it when people attempt to Wikilawyer me :) OK, Wikipedia does not - and has never - required citation for ALL content, otherwise we'd need a citation for the very existence of vacuum tubes to begin with. Only things which are 'likely to be challenged' require verification. The truth of this statement is obvious because there are entire industries (hi-fi, professional recording, and guitar amplification to name but a few) which exist solely because of this fact. Regardless, if you still wish to challenge that, please provide your reasons for disputing this assertion and we'll go from there. Manning (talk) 07:27, 27 January 2012 (UTC)

--insult removed here-- For the effort of tagging the article, or replying here, you could easily find hundreds of references to support this, add at least one of them to this article. LouScheffer (talk) 14:30, 27 January 2012 (UTC)

I think you'll find that has been done. However insulting fellow editors is hardly helpful either. While I and the IP may disagree on this point, at least we didn't insult each other in the process. Manning (talk) 14:47, 27 January 2012 (UTC)

I apologize for insulting anyone, and removed the insult. However, I find it very frustrating when folks spend more time defending an easily modified status quo than fixing the problem. To IP, if you can be troubled to add "weasel words", and *especially* if you are sophisticated enough to go to the talk page and argue your point by referring to Wikipedia conventions by their abbreviations, then you certainly could have googled the very first thing that comes to mind, such as "musicians prefer tubes" or "audiophiles prefer tubes". You get many, many hits hits explaining exactly this, so it's clear it's true. Then if you think it's sufficiently non-obvious that others might question the very same thing, just add the reference instead of the weasel word tag. It's less work AND better for everyone. Likewise to Manning, if it's obvious (and I agree it is) then there will be many easily found references for it. If you type "tube sound" into scholar.google.com (so you only get reasonably reputable references) you'll see the two I added. This is easier than arguing that it's obvious, which will probably never work anyway. LouScheffer (talk) 15:26, 27 January 2012 (UTC)

As something of an expert on this topic the only problem I have is not with the word "most" but with the word "musician" in this context. The broad spread of musicians don't use an amplifier on stage at all, and don't give a damn what technology their home sound system is as long as it sounds passable. The musicians who use amplifiers are tenor and bass guitarists, synth/key players, and mouth harp players. Of these the majority of performing tenor guitarists specifically, and many mouth harp players, prefer to use valve amps; bass guitarists and synth/key players much less so. In my experience performing "musicians" and "audiophiles" are non-intersecting sets. In a nutshell, tenor guitarists operate above amplifier overload, while audiophiles operate below it. Roly Roper ozvalveamps.org — Preceding unsigned comment added by 114.74.146.155 (talk) 15:03, 16 February 2012 (UTC)

Grid Basics

I wrote this section to introduce the basics of what grids are so readers more new to electronics can better understand the following material. Very encyclopedic of me. This section was removed by "sunshine warrior". This writer has competing material and pages and for some reason (he/she) wishes to delete other people's good contributions so his appear more important or better. For instance he has an article titled "easy impedance" (no comment). I'm betting he doesn't even realize his impedance equations are statistical estimations with 1% or so error in particle estimation (like many physics equations are). Let's see if he can respond.

I am fully aware some authors are "hot to trot" electrical experts. However an encyclopedia should be usable by non-experts. And "expert equations" which junk up articles should be deferred to readers who seek them.

You welcome, John Hendrickson.— Preceding unsigned comment added by 70.177.172.35 (talk • contribs)

Your additions were not cited and not encyclopedic. Certainly you have a point about accessibility to readers who do not want to wade through the maths, but your text was not satisfactory. It was chatty and made assumptions. It was not well integrated into the article. Your text was deleted by User:Jc3s5h, and rightly so in my opinion. Binksternet (talk) 19:20, 18 December 2011 (UTC)

John Hendrickson, there's a certain value to some of what you added, but Wikipedia is not a blog or a forum, it's an encyclopedia where formal English is used. This sentence of yours, for example, is rambling suited to a classroom presentation to keep students engaged: "Wave addition and subtraction is simple yet appears very complex how discussed." It's also not even close to correct English. 76.102.1.193 (talk) 16:14, 24 May 2012 (UTC)

Batteries/cells etc

I removed "(nor for the A and B batteries, discussed above)" because as I recall the reason cells are called "AA" is to avoid confusion with the "A battery", and the reason there is no size "B" is similar. However I am not 100% certain on these points. Rich Farmbrough, 14:40, 16 February 2012 (UTC).

And that theory falls flat on its face when you consider the C size battery. Confusion with the "C battery"? 86.150.65.44 (talk) 17:44, 5 August 2012 (UTC)

Technical characteristics

I think this article needs a section on how vacuum tubes are characterized (mu, transconductance, etc. ). I have old manuals around, but if someone is more knowledgeable, I'd defer.--agr (talk) 01:13, 11 April 2012 (UTC)

I'm not sure whether that level of detail is necessary. Part of me says an encyclopedia should be the first place to look for a basic introduction to a subject before moving onto textbooks etc; but part of me says that much of wikipedia is already sum-of-all-knowledge, especially articles relating to physics, maths and science (anywhere you can put complex equations to confuse the majority) so why not... Here's a good article to help you, explaining the physics of thermionic emission and space charge in vacuum tubes, http://www.john-a-harper.com/tubes201 . All you have to do is pick out what's relevant and irrelevant. Are transconductance and amplification factor really that important in the context of this article? --KX36 (talk) 13:23, 29 July 2012 (UTC)

Beam tetrodes vs Pentodes - Subjective

The article curently says "Beam power tubes are noted for improved audio clarity over pentodes - e.g. the "clean" sound of a 6L6 versus the "dirty" sound of an EL34.". I would say audio qualities such as "clarity" are highly subjective and often depend more on the circuit than the tube model or type. From a guitar amplifier point of view, Fender amplifiers are often praised for their clean sound and generally have beam tetrode output tubes (6V6 or 6L6), but Vox amplifiers are similarly often praised for "clean chime", which generally amounts to the same as "clarity", and they use EL84 pentodes for output and either triodes or EF86 pentodes for preamplification too. The whole topic is shrouded in subjective words which don't mean a lot and don't belong in an encyclopedia. I'll wait a while before removing the sentence as I know audiophiles have very strong, often baseless opinions on such matters. To those I say, provide a reliable citation for phrases such as this before putting them in. --KX36 (talk) 13:09, 29 July 2012 (UTC)

It is dubious in the extreme, and since it was unsourced, I have removed it. The situation is made worse because many tubes described as pentodes are actually constructed as beam tetrodes. The claim specifically referenced the EL34, but a surprising number were built as beam tetrodes and virtually all the Russian and Chinese supplied EL34s are actually beam tetrodes (as in: I haven't found one that is not). Philips attempted to produce a low noise design in the pentode tube with their EF8, a four grid 'pentode' which attempted to divert current away from the screen grid (the main source of noise in these types). It was not a success. It should be noted that the main noise characteristics are not down to whether the tube is a pentode or a beam tetrode. It is due to features of the grid geometry, which could have been applied to either configuration. The difference in screen grid current between the beam tetrode and the pentode is not significant enough to provide an audible difference. The triode is a lower noise device simply because it has no (screen) grid current. The beam tetrode does have a lower distortion (but only in push-pull circuits), but this is mostly offset by the larger distortion in the higher gain stage required to drive it. 86.150.65.44 (talk) 18:02, 5 August 2012 (UTC)

Scientific language and correctness

I'm not sure if "electrons are boiled off its surface" is a correct way of putting the phenomena of electron emission. I can't find any guidelines to how populistic/downgraded the language of a scientific article is allowed to be in the introduction. Anyone having a position or some knowledge of that? OxygenBlue (talk) 15:48, 9 January 2013 (UTC)

It certainly sounds unscientific, colloquial, etc. However I've read the same language in several different books describing electron tube operation... so there is some precedent. Jeh (talk) 17:09, 9 January 2013 (UTC)

The middle letters

The article states that the middle letters of tube designations have no meaning. But they do. The example given was the 12AX7 double triode tube. There was also a 12AT7 (medium mu) and a 12AU7 (low mu) tube (this is from memory -- I don't have a reference). Earlkio (talk) 17:22, 21 January 2013 (UTC)

I'm sorry to disillusion you, but the article is quite correct. The letters in the tube designation have no meaning as such. They are simply allocated in serial order as tube types are developed. The next tube allocated after the 12AU7 was the 12AV6 (a double diode triode), then the 12AW6 (a pentode). The designation 12AT7 was allocated just before the 12AU7. The last number is simply the number of 'useful' connections available in the tube type, though there does seem to be some degree of interpretation. Although the letter groups were supposed to be unique for tube designs, there does occasionally seem to be some confusion over the numbering of tube types with the odd duplication (or even triplication). For example, the 'AV' designation for the 12AV6 (double diode triode above) was also used for the 12AV7 (another double triode) as well as the 12AV5 (a beam tetrode) - these last two were found adjacent to each other in an RCA data book. See RETMA tube designation for more information. 86.181.52.76 (talk) 16:50, 12 September 2013 (UTC)

Audiophile

"Professional systems such as music recording studios and public address systems[citation needed] rarely employ tubes in microphone preamplifiers or other applications."

While this statement applies to modern public address systems, the opposite should be noted regarding music recording studios. The vast majority of recording studios will equip several tube-based signal pre-amplifiers. This is often one of several major selling points for a studio. — Preceding unsigned comment added by 174.16.193.95 (talk) 22:00, 15 September 2013 (UTC)

Minor edit war

There appears to be an edit war running with one editor Wtshymanski continually deleting a {{refimprove}} maintenance tag requesting that the unreferenced parts of the article are tagged. In fact, the whole article is almost devoid of the required inline references. Just 28 references cover a very large article. The global {{refimprove}} is thus more appropriate than adding {{refimprove|section}} to every section, or the 350 odd inline {{cn}} tags. –LiveRail < Talk > 09:05, 10 February 2014 (UTC)

Transconductance

For vacuum tubes, transconductance is defined as the change in the plate(anode)/cathode current divided by the corresponding change in the grid/cathode voltage, with a constant plate(anode)/cathode voltage. Typical values of gm 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 rp or ra. The Van der Bijl equation defines their relation as follows: g_m = {\mu \over r_p}[1]

[/Fragment] –LiveRail < Talk > 09:05, 10 February 2014 (UTC)

Good of you to preserve this section. Reading through the article, there is currently no place where it logically belongs (possibly why it was shoe-horned in at the end of the article in the first place). It could be hoped that a place may presents itself in the future. I have dated this post such as to ensure that it does not get archived and lost from sight. DieSwartzPunkt (talk) 10:49, 11 February 2014 (UTC)

As a suggestion, there is already a Wikipedia article on transconductance. Perhaps the text above could be worked into that, and then in this article a mention should be made in the triode description section of it being a transconductance device. Dave Cornutt (talk) 05:08, 16 February 2014 (UTC)

Why in the triode description specifically? Pentodes also have tranconductance. Indeed, the transconductance is usually quoted in manufacturer's characteristics for nearly all amplifying valves (sometimes it is omitted from triodes intended for service as a mixer/oscillator but you can still calculate it from 𝜇 and R_a). –LiveRail < Talk > 16:28, 16 February 2014 (UTC)

It just seemed like a good place to introduce it in the flow of the text. Dave Cornutt (talk) 04:53, 17 February 2014 (UTC)

I went ahead and re-inserted the transconductance discussion into the triode section, with some introductory words, and it seems to flow OK. Feel free to edit if it doesn't suit. Dave Cornutt (talk) 16:57, 21 February 2014 (UTC)

gm -v- g_m

Is it just possible that this is an American versus British usage thing? While 'g_m' would, on the face of it, seem more logical, I turned to the tube manufacturers data sheets to see what they used (as they have to be considered a more reliable source than some text book author). Both Mullard and Brimar use 'gm' in their handbooks as referenced in the edit summary. Mazda also use 'gm' throughout their 1968-1969 data handbook. A C Cossor, unfortunately spelt out 'Mutual conductance'. I had a look at some of the US manufacturers' data sheets (Sylvania, GE, RCA and Raytheon) but this was of no help. All four spelt out the word 'Transconductance' without using the symbol form in all the data sheets I looked at (and there were many of them). –LiveRail < Talk > 17:32, 25 February 2014 (UTC)

I disagree in several respects. First, transconductance is a characteristic of several electronic devices, not just vacuum tubes, so sources consulted for language matters should not be limited to sources about vacuum tubes. Next, newer sources are better than old sources because publishing systems have improved; older sources may not have been able to create subscripts. Also, textbooks are likely to have superior publishing systems than manufacturers' data sheets; the data sheets should be suspected of being unable to create subscripts, or of having authors who are insensitive to typographic niceties.

I will point out The Art of Electronics by a Harvard professor and a scientific instrument designer, published by Cambridge University Press. It uses g_m on page 116 while discussing FETs. Jc3s5h (talk) 18:20, 25 February 2014 (UTC)

• Use subscripted g_m. LiveRail admits that subscripts "seem more logical". Why should WP be less logical? Terman was not the only source that I found that used the subscripts (there were typewritten datasheets that used "gm", but that doesn't mean anything), but Terman is a clear authority. Static resistances use R and dynamic resistances uses r. Static conductance uses G and dynamic conductance uses g. Look at two-port networks and you will see Two-port network#g-parameters: a matrix of subscripted g values. The mutual conductance variable g_m is the same as the transfer conductance g₂₁. Using subscripts is proper. Glrx (talk) 19:36, 27 February 2014 (UTC)

Question for redactors

Dear Sirs redactors from Wikipedia please answer, did the first serial simple of the vacuum tube by Edison had a refrigerant for the electronically cathode as a coolant which was a capacitory water and why cooling the electronically cathode is been most important in a vacuum tubes than cooling the electronically anode?--Alex Sazonov (talk) 13:07, 18 April 2014 (UTC)

I may not completely understand the question. The anode of the vacuum tube needs cooling because the stream of electrons hits it with high velocity - that energy has to be dissipated. Small vacuum tubes rely on heat radiation from the anode for cooling; larger tubes have the anode exposed on the outside of the tube envelope so that they can be directly cooled by circulating air or water. According to one book, it wasn't until 1919 that a way to seal a glass envelope to a metal anode was worked out (that would still hold a vacuum). By 1925 water-cooled vacuum tubes were in use; by 1937 you could obtain a vacuum tube triode for transmitter use that could dissipate 150 kilowatts in the anode (but it only weighed about 35 kg). --Wtshymanski (talk) 17:30, 18 April 2014 (UTC)

Very thanks for your answer Wtshymanski. I think that till these years the serial vacuum tubes by Thomas Edison had a science of a electro-technical but not a science of a electronicall, thats why I think that Thomas Edison had been make the serial vacuum tubes as a electro-technical specialist, but not as a electronically specialist, thats Thomas Edison had made the electronically cathode as the superconductor such as a electro-technical variant with the frozen cooling cell in which was beening a salte water.--Alex Sazonov (talk) 19:59, 18 April 2014 (UTC)

To be fair to Edison, there was no "electronics" field of study when he discovered this phenomenon in a light bulb; perhaps if he'd been a little more curious about the effect, vacuum tubes would have been invented in the 19th century. As far as I know Edison published nothing on superconductivity, which wasn't discovered until 1911 when Edison was more interested in the movie business. --Wtshymanski (talk) 20:15, 18 April 2014 (UTC)

I'm not sure what is being referred to here by "serial sample," but anyway... Edison's cathode was not cooled at all, as he had no separate cathode, only a lamp filament which acted as the cathode once a positively-charged plate was added to the bulb. Of course, the lamp filament was hot, not cold! Later, when practical uses were found for the electron flow from cathode to plate/anode, it was realized that in most circuits it would be desirable to electrically isolate the cathode from the heat source... so separate heater and cathode elements were used. I'm not familiar with tubes that require cooling of the cathode; in most tubes the cathode is very deliberately heated, otherwise electron emission would be quite low! Exceptions of course exist for "cold cathode" tubes, but those tend to be very specialized. Jeh (talk) 21:08, 18 April 2014 (UTC)

Thanks Wtshymanski. So as I think as Edison was thinking in such years if the conductor of a electronically cathode in the vacuum tubes be make as a colding the vacuum tubes must be more powerful lightest and more powerful safely.--Alex Sazonov (talk) 21:36, 18 April 2014 (UTC)

No, it's more like: If the cathode is cold, then you don't have a vacuum tube at all. You have a cold-cathode tube, all examples of which that I know of are filled with gas such as neon, argon, xenon, etc. I don't know where you got the idea that anyone uses "refrigerant" on the cathodes of vacuum tubes. As I pointed out above, a heater element (usually powered by the famous 6.3 or 12.6 volts AC) is deliberately placed inside the tube so as to heat the cathode! Re. cold cathodes, see Cold cathode. Jeh (talk) 21:40, 18 April 2014 (UTC)

Thanks Jeh. If I know well, a cathode always more powerfully than a anode thats why a superconductivity always made at a cathode.--Alex Sazonov (talk) 21:59, 18 April 2014 (UTC)

I have no idea what you're talking about. A cathode is not more "powerfully" than an anode; as W. above pointed out, there are tubes in which the anode must be cooled; I never heard of one where the cathode had to be cooled. And there are no vacuum tubes I ever heard of with superconducting cathodes. In fact, superconductivity would be hugely incompatible with the required behavior of a cathode (emission of electrons). I think you are starting from some fundamentally wrong assumptions. Perhaps "not even wrong." Jeh (talk) 22:24, 18 April 2014 (UTC)

Thank you Jeh. So Jeh, did a powerful electric had been a small conductor of the powerful cathodes? Thats why I always think that all cathodes always are powerful electrodes.--Alex Sazonov (talk) 23:17, 18 April 2014 (UTC)

I don't know how to parse your question; you are not using standard terminology. (e.g.: A "powerful electric" what? Powerful electric current? Field? Train?) But I can tell you that not all cathodes carry much power; high power operation is not characteristic of all vacuum tubes. Perhaps you mean "voltage", but it is the plate (anode), not the cathode, to which high voltage is normally applied... and there are vacuum tubes designed to run on very low plate voltages, too. One application was late-tube-era car radios, with just battery voltage on the plates, and a single transistor final stage for the audio power amp. Jeh (talk) 03:07, 19 April 2014 (UTC)

Thanks a lot for your answer Jeh. I had seen that you always mean a electronics in our discussion but I see that a superconductivity in a electro-technical mean all another science than it mean in a electronics, thats a conductor of all cathodes always is not been a constant in a mathematical physics and I think that all cathodes is beening mostly powerful than all anodes because all cathodes always are powerful electric mine.--Alex Sazonov (talk) 04:52, 19 April 2014 (UTC)

I'm out. Jeh (talk) 06:22, 19 April 2014 (UTC)

Did Thomas Edison know that a cathode always is been a powerful volts?--Alex Sazonov (talk) 07:57, 20 April 2014 (UTC)

I always think that without a cathodes always none had been a anodes because only all a cathodes always had been create a powerful electromagnetic field but a anodes not done it without a cathodes, whats why a electronically p-n transmissions always is been a most important than a electronically n-p transmissions in all electrodes.--Alex Sazonov (talk) 18:21, 21 April 2014 (UTC)

The name (first sentence)

I don't know where "electron tube" is used, but it's not in the U.S.

I don't think British English should be called "standard English". Whose standard? The queen's? deisenbe (talk) 17:48, 13 March 2015 (UTC)

I've reverted the IP who seems to be somewhat confused. On electron tube there does not seem to be much evidence that that is a broadly used current term anywhere. At best it would seem dated. However, where it is found (see this search on IEEE Xplore) it is mostly in American publications. There is Handbook of Electron Tube and Vacuum Techniques (reprint of 1964 publication) from the Amercican Institute of Physics for instance. SpinningSpark 19:21, 13 March 2015 (UTC)

If you will search amazon.com for "electron tube" you will find books and even tubes for sale under that name. This one, for example. That's standard RCA packaging. Jeh (talk) 22:23, 15 March 2015 (UTC)

I removed this, and someone reverted it. "Electron Tube" is not a common usage in the US, period. I am going to correct it again, stop screwing around with it. — Preceding unsigned comment added by 71.204.165.177 (talk • contribs)

Please don't use such agressive language. I would have thought that the use of the term by RCA to describe their product was by itself justification enough to include it in our article. Common or not, the term is clearly in use by some. SpinningSpark 13:47, 13 April 2015 (UTC)

Dear IP, you do not have final authority here no matter how firmly you state your opinion. A name does not have to be a common usage nor current to be listed as an alternate name. You know, I could equally argue that "vacuum tube" is not a "common usage"; the most common is to simply call them "tubes". Book titles and product names are enough to establish that it's not unheard-of and was well accepted in its time. Anyway, there's a disambig page for "Electron tube" that links to here, so we have to mention it here (and boldface it). Jeh (talk) 21:34, 13 April 2015 (UTC)

• Keep electron tube; sources establish its use. Glrx (talk) 01:53, 16 April 2015 (UTC)

Thank you, Glrx. It's worth noting here (just in case the IP would otherwise miss it) that the two books I ref'd were published only a few years ago, so it isn't credible to claim that this is only an arcane usage. Jeh (talk) 18:12, 16 April 2015 (UTC)

New tubes

I did not see mention of this new project.

http://www.korg.com/us/news/2015/012212/

Idyllic press (talk) 23:16, 7 February 2016 (UTC)

Go ahead and add it (don't forget those references). -Elektrik Fanne (talk) 13:44, 6 March 2016 (UTC)

I think we should have a better source than a company press release before adding anything to the article. SpinningSpark 19:42, 6 March 2016 (UTC)

I second Spinningspark. Glrx (talk) 02:43, 9 March 2016 (UTC)

My mistake! I should have specified that it is WP:SECONDARY sources that are required. -Elektrik Fanne (talk) 17:24, 9 March 2016 (UTC)

Top cap connection

An editor maintains that the top cap connection reduces the inter-electrode capacitance. This is quite impossible. The inter-electrode capacitance is determined by the geometry of the filament/cathode, grid(s) and anode sizes and placements. Moving the connection to any of these to the top cap does not change this. On the other hand, moving the connection to a top cap shortens the connection wire which reduces the series inductance of the wire thus improving the frequency response of the device. 86.153.135.110 (talk) 17:00, 14 June 2015 (UTC)

I see where you are coming from here and you are right - at least part. It is not the inter-electrode capacitance that is reduced, but the inter-connection capacitance. You are also correct about the series inductance, but it's the capacitance that is the predominant effect. 212.183.128.237 (talk) 17:06, 14 June 2015 (UTC)

Crikey that was quick! Gotcha - kinda makes sense. I am certain that I read somewhere that the series inductance was the predominant effect as the lead out wires were often fairly long as a result of valves being built similarly to light bulbs (as most early valve were made by light bulb manufacturers until the valves became big enough sellers to spin the production off). 86.153.135.110 (talk) 17:15, 14 June 2015 (UTC)

I've reverted that back to restore the reference I put in. The claim in the edit summary of Unacceptable reference (per WP:ELNO #6). Requires registration. I don't believe the ref says this anyway... shows a complete misunderstanding of the guidelines. WP:EL explicitly does not apply to citations, only external links, and WP:V explicitly allows sources behind paywalls, see WP:PAYWALL. Disbelieving me that the ref says what I claim without first troubling to read the source yourself is a rather poor breach of assuming good faith, and in any case, I provided a link under the page number to a gbooks snippet with the relevant passage so you can readily read it yourself.

The issue about inductance of lead outs requires a source before reinserting. The inductance of the external wiring is surely way more significant than the lead outs. If the top cap wire has to go back under the chassis, where most of the wiring is located, then that will result in a longer wire than one from the base. It could, of course, be going to the top cap of a capacitor instead, but that is all a function of the overall design, not of the valve. Saying that you are "certain that I read somewhere" is just the sort of thinking that led us to require reliable sources. I'm quite peeved that a short contribution I made with three carefully researched reliable sources to back it up got chewed up with completely unsourced information that "had been heard somewhere". SpinningSpark 17:51, 14 June 2015 (UTC)

That I may have read it somwhere may be factual. Contributing to a discussion on what I know and have read is perfectly in order. Since I made no change to the article based on what I read somewhere, what's your problem? 86.153.135.110 (talk) 12:07, 15 June 2015 (UTC)

My problem with you was that you deleted a good reference. The edit concerning inductance was made by 212.183.128.237, not you. Sorry if I implied otherwise, or got two unregistered editors confused. SpinningSpark 14:45, 15 June 2015 (UTC)

The added reference did not support the statement of reduced 'inter electrode capacitance', but only a reduction of anode to grid capacitance. This is not the same thing.

There are four principal reasons for the limitation on frequency response in any valve.

1. The inter electrode capacitance. That is: the capaciance between the grid winding within the anode cylinder or between the grid winding surrounding the cathode (or both). These are entirely within the electrode structure and as (correctly) noted above are fixed by the geometry of that structure and no amount of changing the way lead out wires are arranged or terminated will change them. Thus the article was wrong to claim that the inter electrode capacitance was reduced by using a top cap connection, and the provided reference did not state this. Inter electrode capacitance will limit the frequency response when the valve is operated in common cathode or common anode mode. It is not a significant problem in grounded grid because in this mode the grid acts as a screen between the cathode and anode. The effect in grounded cathode amplifiers can be substantially reduced by the use of a screen grid between the control grid and the anode (the tetrode or pentode construction).
2. The interconnection capacitance. That is: the capacitance between the lead out wires that run bewteen the electrode structure and the external connections (either the base or top cap(s)). Obviously, these can be affected by the way in which the lead out wires are arranged. Using a top cap connection for the grid allows a relatively short and direct connection to the grid at the top of the electrode structure that is kept away from the other lead out wires which are usually at the bottom of the structure. The tetrode or pentode construction does not, in itself, change this capacitance. The capacitances thet exist at 1. and 2. suffer from a problem in that in any valve the actual capcitance affecting the operation is the real capacitance multiplied by the gain of the valve (mu) - The Miller effect.
3. The series inductance of the lead out wires. This is also minimised by keeping the grid wire short (as in connecting to the top cap). This would be negated by using a long external connecting wire from the top cap to below the chassis, which is why such valves are usually installed right next to the RF coil assembly or intermediate frequency transformer. The grid connecting wire(s) then come straight from the top of the coil assembly minimising the series inductance. This series inductance is not multiplied by the valve gain, but it can have other undesired effects. In any common electrode operation, it is the valve's external connection that is earthed (for AC purposes). The series inductance in the lead in wire to the actual electrode itself means that the electrode is not necessarily earthed (to AC) but will have a superimposed signal representing the potential dropped across the series inductance (and itself modified by any shunt capacitance).
4. There is a far less well known effect and one that is seldom documented even in some of the more advanced works on valve technology. A limitation is the transit time of the electrons between the cathode and the anode (via the grid). Many electrical engineers are unaware of the actual physics behind electrical conduction and are very surprised at the speed that electrons travel along a conductor. The electrons themselves are whizzing around at approximately c/3 (c is the speed of light) known as the thermal velocity and is temperature dependant. When a current flows, the whizzing electrons drift along the conductor at an astonishingly slow speed. A current of 1 Amp flowing through an 18 AWG copper wire requires that the electrons drift at 0.093 mm/sec.. Within the valve, the electrons are not moving atom to atom as in a conductor as there are (ideally) no atoms in the vacuum. The electrons thus drift on their own and at a velocity determined by the accelerating voltage (the anode voltage). This a much faster than a sub-millimetre per sec speeds, but still is only of the order of tens of metres per second, for anode voltages around the 250 volt region (at 6.3*10¹⁸ electrons per second for a 10 mA current). As the signal frequency rises, the inherent phase change between grid and anode comes into play because of the delay in the grid modulation reaching the anode. In small signal valves this is an accepted limitation, but valves such as klystrons get around the problem by arranging the biasing and electron velocity to be such that the phase change is an integer multiple of 360 degrees, plus whatever phase change you actually require. Variable frequency klystron oscillators have potentiometers linked to the cavity tuning to vary the anode voltage and in wide frequency versions, switches that make major changes to the biasing to change the oscillation mode.

For audio frequency applications, none of these effects come into play. In the old days of valves built with long lead out wires running through a pinch (like a light bulb) and large electrode structures, a few hundred kilohertz was major problem. As constructions got smaller a few Megahertz was quite achievable. VHF frequencies were achieved with constructions that significantly shortened the connection wires such as in RCA'a 'acorn' series. Even higher frequencies can be achieved using a common grid valve in the anode circuit of a common cathode. Because the common grid's grid voltage is constant, its cathode (and hence the common cathode's anode) is held at a near constant potential. This substantially reduces the effect that grid to anode capacitance has on the grounded cathode device (at the expense of voltage gain but a big improvement in bandwith). Any loss of gain is compensated for by the grounded grid valve. These types of circuits wre common in television tuners where operation well into the hundreds of Megahertz was obtained. — Preceding unsigned comment added by DieSwartzPunkt (talk • contribs) 13:46, 17 June 2015

I thought the top cap connection was to make the High voltage insulation and signal routing less of a problem. Idyllic press (talk) 23:22, 7 February 2016 (UTC)

The above seems to be discussing signal tubes which generally do not operate off particularly high voltages. But you are right: tubes operating at high voltages use a top cap for insulating rather than for signal reasons. The line output and efficiency diode in TV sets usually had top cap connections for the anode or cathode respectively. -Elektrik Fanne (talk) 17:32, 9 March 2016 (UTC)

References

when Wikipedia says electrons are emitted by a hot cathode they are obscure because electrically charged metal vapor atoms are emitted not electrons

when Wikipedia says electrons are emitted by a hot cathode they are obscure, because electrically charged metal vapor atoms are emitted not electrons

only metal atoms are emitted. this is easily proven. electrons have an insignificant mass and move at the speed of light. atoms have up millions of times the mass of electrons and move millions of times slower.

if you turn a phosphorescent TV CRT picture tube so it is facing upward . then apply heater current to the cathode. then apply voltage to the anode terminal until cathode rays hit the screen. you discover that it requires a certain minimum voltage and less than that and the cathode rays are overpowered by gravity and fall to the side because cathode rays are metal vapor atoms that have a negative electrical potential with respect to the anode.. no necessarily an extra electron. but a potential.. that potential causes them to be attracted to the anode.. and if that potential is not high enough then the charged partials are at the mercy of other forces.. in the case of the "upward facing CRT" , gravity is the dominant force. with the same voltage and the same CRT, if you face the CRT downward. the electrons make it to the screen and it glows .

this is utterly simple to understand and if you don't understand. then do the hypothetical test.. it requires less than 100 volts of potential. and a usb charger can be used to power the heater filament. yet 100 volts dc is dangerous — Preceding unsigned comment added by Jonathan scott james (talk • contribs) 04:45, 24 November 2016 (UTC)

Where is this coming from ?

Obscure? In all my years working with vacuum tubes I have heard of no evidence of this. In fact, ions in the tube are bad news all around.

If this was the case

• Vacuum tube envelopes would show signs of this metal being deposited through holes in the anode/plate. They don't.
• A CRT would be dimmer facing up and brighter facing down. They aren't.
• Convergence would change facing up or down.
• There would need to be some correction for the "sagging" beam as it traveled horizontally. There isn't.
• The phosphors would degrade rapidly from the added metal.

If you have done this experiment, please explain the setup. I believe, if you have done it, you are misinterpreting your results.

Regards, -- Steve -- (talk) 03:47, 26 November 2016 (UTC)

Agree completely with EngineerSteve. Jonathan Scott James is flatly wrong. JSJ is arguing against unambiguous statements made in literally every credible reference work on the topic. See, for example, this page at the HyperPhysics site, or this one at schoolphysics.co.uk ("Cathode rays are beams of fast moving electrons"). The cathode emits electrons.

If JSJ were correct, then besides the effects noted by ES (which don't happen).. .

• The cathode would gradually fade (become thinner, eventually develop holes, etc.) as does the source material in e.g. electroplating. (In fact, the source of the electrons emitted by the cathode is the incoming electric current, so none of the cathode material is lost.)
• The raster of CRT TV set that's inverted, or turned on its side, would show the effect, being diverted slightly toward the side of the set closer to the earth. (And no, there are no circuits in a TV set to compensate for this.) Ditto for CRT oscilloscopes.

Note that all of the effects mentioned by ES (and by me) could be observed very easily - if they were real - with a small portable CRT TV set or CRT oscilloscope There is no need to hook up any voltages to a bare CRT as JSJ suggests.

JSJ is also wrong about electrons' mass: while tiny, it is not zero. They move faster under higher accelerating voltage), but no way do they move at the speed of light. In a typical color TV CRT they might move at around 1/10 that speed. In small electron tubes (why do you think they're called electron tubes?), they move at much smaller speeds. (JSJ may be thinking of photons?)

There is no doubt or ambiguity about this. Any edits to the article in support of JSJ's position will be immediately reverted.

Jeh (talk) 04:55, 26 November 2016 (UTC)

JSJ also doesn't know what "obscure" means. Jeh (talk) 05:06, 26 November 2016 (UTC)

Uncited helium infiltration entry

There is an uncited and citation needed entry made in regards to helium infiltration of vacuum tubes causing non-functionality. I'll await a discussion or citation for a time, then I'll remove that which I've never observed in my life (and I've worked on many a vacuum tube circuit in my day and I'm conversant enough in the technology to know what a humbuckling coil is and worked in the field through germanium transistors, silicon transistors, IC's and VSLI integration).Wzrd1 (talk) 06:05, 7 January 2017 (UTC)

Helium diffusion inward is a known issue in photomultiplier tubes; see http://www.et-enterprises.com/files/file/technical-information/rp101_effect%20of%20exposure%20to%20helium%20on%20photomultiplier%20performance%20and%20lifetime.pdf . I haven't found "helium diffusion" mentioned in context of any other sort of vacuum tube. Some VR tubes are of course deliberately filled with He.

This short monograph discusses the diffusion issue with PMTs. Although there is no organization affiliation mentioned, the first part of the URL suggests "high energy physics", rl.ac.uk points to the Rutherford Appleton Laboratory in the UK. High-energy physics labs do use PMTs in "fisheye" scintillation detectors at the target ends of particle accelerators.

The opposite issue (loss of helium) was a known problem with the earliest commercial HeNe laser tubes. The He molecule is so small and inert that it could "migrate" or "diffuse" right through the glass or the electrode seals. The partial pressure of He inside the tube was higher than that in the atmosphere, so it left. Ne could not migrate, leaving the tube without enough He and hence loss of power. The problem lended itself to an easy, low-tech solution: Turn something like an empty aquarium upside down over the tube and fill it from the open bottom with helium. With the He outside the tube at approximately 1 atm, it would then migrate in. "Balloon gas", which has some amounts of many things besides helium, could even be used because only helium was small enough to make the journey. If the laser assembly was small enough the whole thing could be put in the aquarium, and left powered, and the laser output monitored to determine when to stop (it would rise to a peak and then start to fall off again, which is when you want to stop). The problem was mostly fixed by going to "hard seals". ("humbucking", not "humbuckling", btw) Jeh (talk) 08:08, 7 January 2017 (UTC)

Perhaps, we should edit for PMT's then, as they'd stand the greatest chance for helium exposure in a physics environment. Helium infiltration in earth's atmosphere is extremely unlikely. As for humbucking, yeah, my bad. Late night edit. Interesting solution for the HeNe laser tube though, helium is certainly a capricious element.Wzrd1 (talk) 16:42, 7 January 2017 (UTC)

Well, I found a reference for a more general statement. https://books.google.com/books?id=IUZVffQLFKQC&pg=PA529&lpg=PA529&dq=helium+diffusion+vacuum+tube&source=bl&ots=64q5AOT75r&sig=i5IMrgV7ISbQH4DZFKRXeGBh9Ig&hl=en&sa=X&ved=0ahUKEwjW6Zb967DRAhUQ7WMKHc53DysQ6AEIbzAT#v=onepage&q=helium%20diffusion%20vacuum%20tube&f=false "Helium can readily permeate through many glasses used for vacuum tubes." PMTs are particularly sensitive because of how they work. Image pickup tubes as described now in the article are sensitive for the same reason and because of their large glass area. Jeh (talk) 20:18, 7 January 2017 (UTC)

And this shows that He diffusion is a problem in PMTs even at 1 atm. High pressures are not required. Jeh (talk) 20:31, 7 January 2017 (UTC)

Commonest cause of failure? Not so sure.

'tubes were by far the most common cause of failure in electronic equipment, and consumers were expected to be able to replace tubes themselves'

This claim is folkloric, and disputable. Ask any vintage kit restorer; many vacuum tubes from as far back as the 1920's are still serviceable, whereas certain types of passive components tend to have failed. I don't think this was any different in the vaccum tube's heyday. Consumers used to 'jockey' the tubes in radios and amplifiers simply because they were pluggable whereas other components were not. That does not necessarily mean that the fault had been correctly diagnosed. --Anteaus (talk) 19:29, 7 March 2014 (UTC)

A lot depends on the types of tubes used; the quantity in any piece of equipment and the manner in which they are used. In Europe, the EF50 tube made by Philips/Mullard turned out to be notoriously unreliable. Millions were manufactured and any that made it to museums are likely to be unserviceable. On the other hand, the AC/ series of tubes produced by Mazda, turned out to be very reliable indeed. These tubes became a standard line up in many UK receiver designs, and service shops stocked up on spares ready to swap a failed tube with the minimum of delay. Unfortunately (for the service shops) spares were rarely required and any found in museums are most likely brand new.

The number of tubes also has an impact. A six tube radio set will, on average, run for several years before a tube fails - helped by the fact that the tubes are not worked particularly hard. When television sets appeared, they could use twenty tubes or more, and failure was much more frequent, especially as some of the tubes (notably the line output tube) were often worked very hard indeed, particularly when miniature tubes were adopted. Indeed any 1970's era TV set could almost be guaranteed to break down within six months of aquisition. Up to the second world war, it was generally considered that the reliabilty of any tube based equipment was inversely proportional to the number of tubes employed. The largest project at that time used 250 tubes and was considered very unreliable. It was the designer of the Colossus code breaking computer, Tommy Flowers who realised that the majority of the unreliabilty came from the stresses that the tubes endure during power down and power up (mostly the later). This allowed him to design and build a 2600 tube computer that had an acceptable reliabilty (given its war time role).

A company that I worked for still had a Ferranti Mercury tube based computer when I joined. The machine would rarely run for more than three to four hours before it required yet another tube to be replaced. DieSwartzPunkt (talk) 18:31, 15 March 2014 (UTC)

I removed the comment, as it was incorrect. The most common failure, then and now, were the capacitors, particularly the electrolytic capacitors. — Preceding unsigned comment added by 71.204.165.177 (talk) 03:21, 9 April 2015 (UTC)

Not necessarily. Electrolytic capacitors will generally have a longer life than most of the tubes provided the equipment remains operational. This is the main reason why the tubes were plug-in parts rather than being permanently soldered in as the capacitors were. The capacitors do dry out, but this still takes longer than a tube will last. Where electrolytic capacitors do give problems is when the equipment remains unpowered for any length of time. Having said that it is possible to repower such equipment without problems by adopting a few precautions. 86.153.135.110 (talk) 10:09, 12 June 2015 (UTC)

I agree with the above anon user as I started with vacuum tubes in the 50's. The tubes were the most common failure during their original lives, but not necessarily today. The electrolytics of old would "deform" meaning the dielectric layer would degrade, but this was due to not having voltage applied for long periods. The dielectric layer was formed by a process that applied a voltage and this degradation could be reversed. Carefully applying a current limited voltage *may* restore old electrolytics IF they have this problem. I cannot address the "drying out" issue because I have no direct experience; I do not know if it is real or assumed as the problem which is actually the "deforming" issue. But in days-of-old, the electrolytics lasted a long time. Vacuum tube cathode emission usually decreased over time. My dad was in vavuum tubes and designed CRTs for Zenith (Rauland) as well as scan converter tubes into the 70's with Warneke (sp). I came here to find out when 7 & 9 pin miniatures were introduced to help date a Victrola in my sister's house/estate. What I read in the article was well done and agrees with my recollections. Regards, -- Steve -- (talk) 14:15, 4 August 2016 (UTC)

In Section 3.10, Whirlwind and "special-quality" tubes, there is a statement that heater voltages were reduced on tubes in the standby unit, to cause weaker tubes to fail on standby instead of in service. Isn't it that the filament voltages were increased, not reduced? Incrased voltage would cause heaters to fail sooner, revealing the weaker tubes, I think. Maurice Fox (talk) 01:16, 16 August 2017 (UTC)

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Barium aluminate?

I see a lot of references in the literature to a "Barium Aluminate" that's used as a gas absorber in vacuum tubes. Apparently the barium on the surface binds with stray oxygen atoms, then the aluminum steals them, refreshing the surface for more absorption. There is no page for "barium aluminate", and I can't find a reference to the chemical formula for it. Anyone got a good reference?

Riventree (talk) 00:29, 3 March 2018 (UTC)

Should we mention integrated thermionic circuits in this article

Since we mention Nanoscale vacuum-channel transistor perhaps the earlier integrated thermionic circuits could be mentioned. They aren't in 'tubes' but use thermionic emission - US DOE investigated ~1980 for geothermal applications around 500 °C.[1] - Rod57 (talk) 17:23, 9 April 2018 (UTC)

Language consensus

Can we have a consensus on the language to use for this article so that we can put an {{American English}} or {{British english}} template on it.

It's pretty obviously in American English (color TV) and has been since its earliest edits. Even the title uses the American term (tube) rather than British valve. SpinningSpark 17:08, 21 November 2018 (UTC)