Are DC flybacks full-wave or half-wave

[MRMILSTAR]

I've never torn open a DC flyback transformer. Is the output half-wave or full-wave rectified? I am guessing that its half-wave because the schematics that I've seen of flybacks show only a single diode.

[Mads Barnkob]

Yeah its half-wave with a single diode or a chain of diodes in series.

[davekni]

I haven't torn one part either.  As Mads said, it is definitely half-wave.  That can be measured by comparing DC output voltage with asymmetric input waveforms.

My understanding is that DC flyback transformers generally have multiple winding sections with diodes between sections.  This makes much of the parasitic capacitance across DC rather than AC, raising secondary self-resonance frequency much higher than can be accomplished in an AC flyback.  Also reduces corona stress internally.

[johnnyzoo]

Unless I'm missing something, flyback converters are inherently "half-wave" due to how they operate (storing and releasing energy in the core magnetic field). So any TV/CRT transformer that is driven by a flyback converter must be half-wave rectified for proper operation.

[Mads Barnkob]

Unless I'm missing something, flyback converters are inherently "half-wave" due to how they operate (storing and releasing energy in the core magnetic field). So any TV/CRT transformer that is driven by a flyback converter must be half-wave rectified for proper operation.

That is correct. But the half-wave rectification is done internally in modern flyback transformers, whereas it was done externally with a rectifier tube in old flyback transformers (which is just a disk high voltage AC transformer)

I go through 4 different kinds of flyback transformers in this video. At 2:40 in this video you can see the old transformer with tube.