Structure of a transformer

A transformer comprising two E-shaped core parts, each having a back from one side of which projects at right angles thereto three spaced-apart legs, positioned with the extremities of the legs abutting such as to define a center leg and a leg at either side thereof between the backs of the E-shaped core parts, a spool on which is wound a coil positioned on the center leg and an I-shaped core part of a length and breadth corresponding to the length and breadth of the backs of the E-shaped core parts positioned in engagement with the back of one of the E-shaped core parts, means defining an open groove at the interfaces exclusively in one of said interfaces, a coil wound on the I-shaped core part, the windings of which are received in said groove and a C-shaped, elastically-engageable clamp means encompassing the core parts and clamping the E-shaped core parts in engagement with each other and the I-shaped core part in engagement with the back of said one of the E-shaped core parts.