Talk:Vacuum tube

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)

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)

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)

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)

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).