A transformer and method of making a transformer is disclosed. The transformer has a magnetic core, a first winding and a second winding. The first and second windings are wound about the core, and an insulating jacket, which includes a plurality of protrusion, mounted about the core. One of the first and second windings is wound about the insulating jacket. The core is preferably a toroid core in one embodiment. Some of the anchors are on the inner diameter of the insulating jacket, and other on the outer diameter of the insulating jacket. The anchors are preferably spaced at equal circumferential positions. The windings are a progressive windings, with various sections, and each section has a number of layers. Each progressive section is anchored by at least two of the anchors. The first and second windings are wound directly on the core insulation, and the insulating jacket is mounted directly on the core. The windings are separated by protrusions having sufficient size to provide electrical clearance and reduce electrical creepage.