MOVABLE CORE FORMING METHOD OF DIFFERENTIAL TRANSFORMER

PROBLEM TO BE SOLVED: To provide a differential transformer at a low cost in which quality is improved by dissolving ununiformity of magnetic flux flow and ensuring linearity of an induced voltage to displacement. SOLUTION: A movable core 41 of a differential transformer includes a core main body part 42 and a pin part 43 which are welded by stud welding. The pin part 43 is arranged on the upper electrode side of the stud welding machine, and a protruding part 43a faces downward. The core main body part 42 is arranged on the lower electrode side. The upper electrode is made to descend toward the lower electrode side, and a current is made to flow in the state that the pin part 43 is pressed against the core main body part 42, thereby performing welding.