Abstract: A method of manufacturing a transformer with coaxial coils. A coil bobbin (1) is provided with a first flange (3) and a second flange (5) between which a winding space is informed in which a first coil (9) is wound. Around the first coil an electrically insulated foil (13) is fitted, on which one or more second coils (15, 17) are wound. An essentially U-shaped spacer (23) made of an electrically insulating material is placed, before the winding of the second coil (15, 17), around the insulating foil (13) such that its members (27) extend axially into the winding space. Each of the members (27) is provided near the first flange (3) with a first radial projection (29) and near the second flange (5) with a second radial projection (31). These projections define a minimum possible distance between the second coil (15, 17) and the first and second flanges.

Abstract: A method coil bobbin (1) with a first flange (3) and a second flange (5) between which a winding space is formed in which a first coil (9) is wound. Around the first coil and electrically insulated foil (13) is fitted, on which one or more second coils (15, 17) are wound. An essentially U-shaped spacer (23) made of an electrically insulating material is placed, before the winding of the second coil (15, 17), around the insulating foil (13) such that its members (27) extend axially into the winding space. Each of the members (27) is provided near the first flange (3) with a first radial projection (29) and near the second flange (5) with a second radial projection (31). These projections define a minimum possible distance between the second coil (15, 17) and the first and second flanges. Each member (27) of the spacer is perferably also provided with at least a third radial projection (33) which separates two successive second coils (15 and 17) from each other in the axial direction.