Scoposcopy: EMJ Partner Coils Frequency-Phase Relationship

Here is an illustration of the phase relationship between the “partnered” coils when the primary is driven by a sine wave from the F43 function generator. The primary (L1) is overlaid on the L2 coil, the oppositely wound L3 coil is adjacent to the L1-L2 pair on the flyback transformer core.

I predicted that this would happen as the frequency increased. The truly “Cancelling” effect of the partnered coils only happens at DC or low frequencies. At high frequencies the two coils begin to go out of phase until finally they are 180 degrees opposite. So depending on the frequency of the drive signal the partnered coils can be entirely bucking or entirely aiding, or somewhere in between, without changing winding or connection polarity.

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