Talk:Center tap

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Electronics Mid‑importance

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Questioning the advantages of the central-tap rectifier[edit]

I can't see any advantages of the central-tap rectifier to the more usual rectifier without the central tap. The first one uses a larger transformer than is needed, only to save a couple of diodes. It is easier to understand, perhaps, but is clearly a couple of single-wave rectifiers in sync, therefore a couple of inefficient rectifiers instead of a single efficient one. -- NIC1138 (talk) 04:32, 25 January 2009 (UTC)[reply]

Some diodes are more expensive than others. At a wall-wart scale of power output the differences are minor but larger rectifiers exist. In vacuum-tube equipment you may not have wanted the space, heat, and economic penalties of two more 5Y3 rectifiers instead of a tap on a winding. Similarly, if you're building an aluminum pot line, two more "diodes" could take a huge amount of space. --Wtshymanski (talk) 16:01, 25 January 2009 (UTC)[reply]

For vacuum tubes, it was usual to have a tube with one cathode and two anodes. As far as I know, tube bridge rectifiers are rare. For modern low voltage power supplies, the diode drop is significant. Gah4 (talk) 21:03, 6 June 2019 (UTC)[reply]

Phase and rectifiers[edit]

"These two 12 VAC supplies are 180 degrees out of phase with each other, thus making it easy to derive positive and negative 12 volt DC power supplies from them."

That the two AC sources from a VCT are out of phase does refuce the parts count of (a typically older-style) full wave rectifier. However the phase dofference has *nothing* to do with the above paragraph's conclusion: "thus making it easy to derive positive and negative 12 volt DC power supplies from them." That the windings are simply split, yes. But the phase matters not at all because (duh) DC has no phase. VCTs by themselves are relatively easy to umderstand. But in schematics, I find them harder to figure out. I think for a noob (ment positively), the conflation in the above paragraph is a real head scratcher. If I'm wrong abouth this and there is some obscure config where phase difference does help, then perhaps the para could be teased apart. Thanks (written by: 2600:1702:1fa0:4e10:70ef:45a3:53c1:7062)

Partly, but not completely, true. You can generate a +/- (dual polarity) supply with two half-wave rectifiers. The advantage of a center-tap is that, with a bridge rectifier, you can generate a double full-wave rectifier. That means much simpler filtering. Gah4 (talk) 03:51, 1 June 2020 (UTC)[reply]

center-tapped bridge rectifier[edit]

Should the article mention the use of a bridge rectifier, with a center tapped transformer, to generate a center-tapped DC power supply? It seems to hint at it, as the above comment suggests, but not say it. Gah4 (talk) 03:53, 1 June 2020 (UTC)[reply]

SMPS[edit]

The article mentions the use of center tap rectifiers in switch-mode power supplies. It seems to me that this isn't quite right. They are used in low voltage power supplies, where the voltage drop of a bridge would be too much. It does happen that those are often SMPS, but if one was building a high voltage power supply, maybe not. Many microprocessors now need a 1 volt power supply, so you don't want two diode drops along the way. As well as I know, they use switched MOSFETs instead of diodes, though. Maybe that should be mentioned, too. Gah4 (talk) 00:55, 20 February 2021 (UTC)[reply]