A planar transformer includes first and second windings that may be comprised of electrically conductive traces etched onto one or more printed circuit boards. The printed circuit boards may be arranged in various orientations so as to change the turns ratio of the planar transformer. In one embodiment, the printed circuit boards are substantially similar and may be electrically connected via connectors that separate the circuit boards. Insulating sleeves may be inserted between the printed circuit boards in an interleaved configuration.