Rectifiers

[Enzo]

When we rectify AC say from a transformer, we can have half-wave, like a typical Fender bias supply. Or we can have full wave. Very common full wave circuit is the bridge, which is four diodes. But around here, we don't seem to have a term for the center tapped feed to a pair of diodes Some folks call it a bridge, though it is not

I am currently reading a book about high power motors and controls, specifically those used in railroad locomotives. Locomotives can have DC or AC motors, depending on the design and the preferences of the railroad company that buys it. Some systems use DC voltage - in particular the third rail system used in NYC railroads. Most catenary systems - overhead wire -- are AC. 25Hz is typical. The motors in the locomotive are not typically driven directly of this, and in fact an AC catenary can suply power to locos with DC motors, they rectify the AC power.

So in reading about this I encountered a basic motor circuit for DC motor with AC power mains. First option was a bridge - four diodes. The next was a center tap with two rectifiers. They call it "push-pull". Been staring at that basic circuit for decades, and in all that time, push-pull never occurred to me. But I like it. It is descriptive and is easy to grok.

[Mick Bailey]

I've always considered the regular tube amp PSU with a centre tapped secondary as a full wave circuit. I think of half wave, full wave and bridge when looking at rectification. If I read full-wave, I mentally distinguish this from a bridge, though a bridge is full wave. Isn't it fascinating how we internalise the way things work for our own convenience. A kind of flat-earth model that isn't strictly correct, but gets us by. I do the same with transistor circuits when looking at how something works - I just think "this goes high, that goes low" where someone else may be thinking in terms of outright mathematical theory.

[Dave H]

I call it a two diode full wave rectifier.

[pdf64]

Merlin refers to it as a two phase rectifier http://www.valvewizard.co.uk/bridge.html
But yes, I prefer the ‘push pull’ terminology, describes its operation nicely

[Mick Bailey]

Two phase rectification encompasses the 180 degree phasing of a centre tapped transformer with the 90 degree phasing of a two-phase supply (such as found on some motorcycles and in early power distribution) and the rectification methods are not necessarily the same - some two phase rectifiers use 4 diodes. I'll stick with my centre tapped full wave model for my own purposes.