Transformer for power supply

A transformer for use in a power supply, comprising:

• a primary winding;
• a secondary winding;
• a bobbin on which the primary winding and the secondary winding are separately wound, said bobbin being provided with a magnetic core insertion hole, said bobbin having a trunk portion through which the magnetic core insertion hole is formed, and plural bases connected at least to both ends of the trunk portion, said trunk portion having a wire winding area partitioned into plural regions by middle guards, each of said bases having plural terminals connected thereto;
• and
• a core subassembly including cores and connected to the bobbin, the core subassembly forming a closed magnetic loop to magnetically couple the primary and secondary windings;
• wherein the primary winding is wound on one of the regions of the trunk portion and has ends connected with different terminals of the bases;
• wherein the secondary winding is wound on another of the regions of the trunk portion and has ends connected with different terminals of the bases other than the terminals with which the ends of the primary winding are connected;
• wherein an inside core of the core subassembly is inserted in and located inside the magnetic core insertion hole, whereas an outside core of the subassembly is located outside the magnetic core insertion hole, at least some parts of the core subassembly being adhesively bonded to the bases;
• wherein the trunk portion of the bobbin is provided with an opening between the regions on which the windings are wound to expose a part of the core inserted in the magnetic core insertion hole;
• wherein the core located inside the magnetic core insertion hole and the core located outside the magnetic core insertion hole are adhesively bonded together through the opening in the trunk portion;
• and
• wherein a spacer is inserted between the core located inside the magnetic core insertion hole and the core located outside the magnetic core insertion hole at a location of the opening, and wherein the core located inside the magnetic core insertion hole and the core located outside the magnetic core insertion hole are adhesively bonded together through the opening via the spacer.