[sdiy] Polyphase transformers

[cheater cheater]

Hi,
I have been reading up on directional couplers lately and saw mention
of polyphase transformers. Supposedly they can output copies the
signal that is input, rotated in pi/4 steps. Sounds like a fairly fun
way to do a phaser. Anyone ever use one of those? Are there any
circuits that use this specifically?

Quote from wikipedia:
For three-phase supplies, a bank of three individual single-phase
transformers can be used, or all three phases can be incorporated as a
single three-phase transformer. In this case, the magnetic circuits
are connected together, the core thus containing a three-phase flow of
flux.[49] A number of winding configurations are possible, giving rise
to different attributes and phase shifts.[50] One particular polyphase
configuration is the zigzag transformer, used for grounding and in the
suppression of harmonic currents.[51]

Cheers,
D.