A planar magnetic structure has an electrically insulating carrier made up of a base portion and opposed upstanding sidewalls. A plurality of planar primary windings and planar secondary windings are interstitially disposed within the carrier with planar dielectric spacers located between each adjacent pair of windings. A ferrite core envelopes the assembly to magnetically couple the windings. The carrier and windings form at least two spaces-apart sets of cooperating registration features which maintain the windings in fixed alignment with the carrier.