Talk:Push–pull output

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Drawing Request

It would be amazing to have an actual drawing of a totem-pole schematic here :)

Be amazed. Dicklyon (talk) 22:22, 14 April 2011 (UTC)[reply]

Too bad it's not illustrating a push-pull output. I don't know what it's illustrating. PNP and NPN transistors? Collector of one hooked to the emitter of the other? It'd be nice to acknowledge the bias problem, as well. An incorrect picture is worse than no picture. --Wtshymanski (talk) 13:20, 14 September 2011 (UTC)[reply]

Better picture found, showing + and - power supplies and load, also a tube-type amp schematic with center-tapped transformer. --Wtshymanski (talk) 15:32, 14 September 2011 (UTC)[reply]

Expansion

As usual, no history - push-pull amplifiers are designed with out comment in the 1945 Radiotron handbook, so doubtless the technique is nearly as old as vacuum tubes. I've tried to put in some explanation as to *why* you would want these various perversions in a circuit, but I can't find any history yet. --Wtshymanski (talk) 21:43, 29 November 2012 (UTC)[reply]

Colpitts didn't claim the push-pull principle in 1915 and that's running pretty far back into tube history; one book suggests that carbon microphone capsules were used as telephone circuit amplifiers in push-pull, so maybe it wasn't considered a patentable innovation. --Wtshymanski (talk) 21:17, 30 November 2012 (UTC)[reply]

Also, the audion predated the vacuum tube, so if a push-pull system was devised using audion tubes, then the push-pull concept definitely pre dated vacuum tubes. An example of a push-pull carbon amplifier cn be found here (approx halfway down - Brown type V microphione amplifier though as it is dated to ~1924, it doesn't predate the audion claim). I have not found an example that predates this design but that doesn't mean that one doesn't exist. DieSwartzPunkt (talk) 09:53, 1 December 2012 (UTC)[reply]

Our resident edit warrior, Wtshymanski is claiming that a vacuum tube and an audion are the same thing. They most certainly are not. They didn't do the same job and didn't even remotely work the same way. Of course, he didn't claim it here, just popped it in an edit summary as a diversion while deleting a {{cn}} tag that he feels does not belong in his encyclopedia (WP:OWNERSHIP) without bothering to provide the required citation. Once again Wtshymanski is not letting his lack of knowledge on a subject get in the way of a good edit war and in pursuit of which doesn't even trouble himself to discuss the issue here before deleting the requirement for a reference from the article. 86.145.244.183 (talk) 13:26, 12 December 2012 (UTC)[reply]

Are things really that bleak in the UK that *this* is how you entertain yourself? It's an evacuated tube with a heated filament - only one of DeForrest's lawyers would argue that it's anything but a vacuum tube, and for the purposes of discussing push-pull amplifiers that whol controversy is immaterial. It's too bad all this energy isn't being used to add content to articles instead of for Wikistalking. This is not doing anythig to dispel my prejudices against editors using anonymous IP addressess, either. --Wtshymanski (talk) 14:13, 12 December 2012 (UTC)[reply]

The structure of the audion may be similar to a vacuum tube, but there the similarity ends. The audion is not an evacuated bulb in that the presence of air was essential for its operation. The principal failure mode of the audion was that the low pressure gas filling was adsorbed into the metal parts preventing it from working. Ironically, this adsorption slowly converted the device into a vacuum tube. The audion worked as a detector and an amplifier (though was non linear). The vacuum tube was incapable of operation as a detector but worked as a linear amplifier (though techniques were worked out subsequently that made it detect).

The operation of the two devices is very different. The vacuum triode requires a lower anode (plate) voltage than the constructionally equivalent audion. More importantly, the vacuum triode must have a negative grid bias which the audion did not require (because of its totally different modus operandi). Even if the audion was provided with negative grid bias, it wouldn't have achieved anything as grid current would be present in the audion unlike the vacuum triode. This again is a consequence of the differing modus operandi.

De Forest himself attempted unsuccessfully to argue that his audion was the same invention as the vacuum tube. He presumably suffered from the same problem as you in that he also did not have the faintest idea how the audion worked (even though he had invented it). It was Edwin Armstrong who eventually figured out its modus operandi and established that they were two very different devices. Armstrong was not a patent lawyer by the way. DieSwartzPunkt (talk) 15:03, 12 December 2012 (UTC)[reply]

There are still hints in the article that the push-pull technique was developed for carbon amplifiers, but there is, as yet, no evidence that this predated Colpitts's patent. DieSwartzPunkt (talk) 15:03, 12 December 2012 (UTC)[reply]

Wtshymanski has now provided a cite that the technique predates the audion by some considerable margin. But in spite of that he has reinserted the (now) incorrect claim that it was developed in the early years of vacuum tubes. Whether an audion can be considered a vacuum tube is now moot as the technique, as was suspected, predates both. In any event, the sentence added nothing to the article as was.

I might also observe, that I make it three editors who have told you that you are wrong and you still will not accept the fact. A pattern that I have observed on many previous occassions. I B Wright (talk) 17:29, 12 December 2012 (UTC)[reply]

{years later} As it turns out, not three editors but one editor wearing three socks? --Wtshymanski (talk) 19:34, 26 January 2023 (UTC)[reply]

The only reason there's any history in this article at all is because I found some. Read the sentence - it didn't say it "originated" with tubes, only that it was "developed". The Radiotron handbook is unhelpful in descrbing how the world learned about corssover distortion and bias. --Wtshymanski (talk) 19:22, 12 December 2012 (UTC)[reply]

Well congratulations on finding the much needed reference and adding it to the article. I was fairly certain that it was developed in the late 19th century, but unfortunately had not found any evidence. However, you then resort to your usual obfuscation of the point in hand. Of course the push pull technique was developed with tubes. It was also developed with carbon based amplifiers. We now know that it was also developed with audion tubes. It was further developed with transistors. It was even further developed with MOSFETs and so on and so forth, so the claim is entirely vacuous. The point of interest here is when it was first used. You have provided a cite with a date which as it is a patent may well be the first use. But patents aren't always as reliable as one would hope in this regard, but this one is adequate for the purposes of the article.

I should have realised that the claim was yours to start with. After all, this is your encyclopedia and you have self appointed yourself as the arbiter of what may or may not appear. You have consistently demonstrated that you don't tolerate anyone altering or removing your contributions or changes. The editing screen used to have a statement on it advising editors not to submit content if they don't want it deleted or altered. Although the statement is gone, it still holds true. Despite your delusions, this is not your encyclopedia and you are not the arbiter of its content. DieSwartzPunkt (talk) 17:31, 13 December 2012 (UTC)[reply]

Definition

I think we need to distinguish between push-pull and totem pole/complementary pair. To me, the push-pull term applies only to output stages that use a centre-ht output transformer. Then the distinction between totem pole and complementary pair depends on the polarity of the transistors used with complementary pair being a subclassification of totem pole. Typical design for a complementary pair uses either two completely complementary darlingtons or else a pair that is complementary in their first transistor, to get the emitter follower transfer function, but both NPN in their second pair to save on silicon cost. 213.122.76.96 (talk) 20:35, 12 April 2014 (UTC) David J Greaves.[reply]

Requiring a transformer would be way too narrowing; we are not stuck with vacuum tubes. See Howowitz and Hill or this book. Dicklyon (talk) 22:36, 12 April 2014 (UTC)[reply]

I's kind of hard to argue with Howowitz and Hill (page 106 in 3rd edition). but the transformer with transistors circuit is common in switch-mode PSUs especially above 100W, so most desktop PCs have this internally, thus we are in no way stuck with vacuum tubes, but it's not actually an output here as the transformer secondary feeds into rectifiers. Similar push-pull drive is used with unipolar stepper motors - maybe a page on "push-pull (electronic)" or "push-pull drive (electronic)" is needed (without "output" in the title). Jasen betts (talk) 10:09, 12 March 2020 (UTC)[reply]