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]