Abstract: A transformer includes a first electrical conductor, a second electrical conductor and a core. The second electrical conductor is electromagnetically coupled with the first electrical conductor. The second electrical conductor includes at least one multilayer spiral coil, which is formed by winding a conductive wire and has a through hole at its central portion. Both ends of the conductive wire extend outward from a periphery of the multilayer spiral coil. The core penetrates through the through hole and covers at least one portion of the first electrical conductor and the second electrical conductor.

Abstract: A transformer includes a first electrical conductor, a second electrical conductor and a core. The second electrical conductor is electromagnetically coupled with the first electrical conductor. The second electrical conductor includes at least one multilayer spiral coil, which is formed by winding a conductive wire and has a through hole at its central portion. Both ends of the conductive wire extend outward from a periphery of the multilayer spiral coil. The core penetrates through the through hole and covers at least one portion of the first electrical conductor and the second electrical conductor.

Abstract: A low profile transformer includes a first core and a second core respectively having a projection, a first printed circuit board and a second printed circuit board serving as primary windings of the transformer and having a hole for allowing the projections of the cores to penetrate therethrough, respectively, and an insulation wire wound around the projections of the cores as secondary windings of the transformer. The low profile transformer becomes smaller in size and lighter in weight and can meet the isolation safety standard and reduce the manufacturing costs. Furthermore, a variety of cores can be applied to the low profile transformer for a wide range of electrical current loading.

Abstract: A linear filter is disclosed including a metal core, a bobbin surrounded said metal core for spinning around electric lines to form coils thereon, a plurality of metal pins disposed on said bobbin for providing electrical signals to said coils, and a plug disposed between said metal core and said bobbin for filling a gap between said metal core and said bobbin to prevent said metal core from moving.

Abstract: The invention discloses the design of a low profile transformer, which is smaller in size and lighter in weight. The low profile transformer will meet the isolation safety standard and is manufactured with low cost. Furthermore, a variety of cores could be applied to the low profile transformer for a wide range of electrical current loading.