The history of a new direction in transformer engineering is described. The operation of the new transformers is based on the principle of electromotive force induction in a winding with a magnetic circuit. With the new arrangement of the windings (or winding), together which perform the functions of the electrical and magnetic parts of the transformer, the windings (magnetic circuits) in one transformer are perpendicular to each other, and with mutual coverage of each other. This ensures the use of this principle of electromotive force induction. The materials that make up the transformer are used in a complex way: one material both for the manufacture of magnetic circuits and for the manufacture of electrical windings of the transformer. In this case, we can refuse copper. As a result, combined windings-magnetic cores can be made of a single material with sufficient electrical and magnetic properties, such as pure iron. For the complex use of the winding-magnetic core in a single-phase transformer, the “monkey knot” lineup is proposed.