Abstract: A position-detecting sensor comprises a magnetic recording medium carried on a moving object and having a signal track recording a magnetic signal, a first MR element disposed nearby the magnetic recording medium and varying its internal resistance by sensing the magnetism of the magnetic recording medium, and a magnetic sensor electrically picking up resistance variation of the MR element and detecting the magnetic signal of the magnetic recording medium. In the position-detecting sensor, the present invention is arranged by providing a second magnetic signal track on the magnetic recording medium in addition to the signal track, disposing a second MR element nearby the second magnetic signal track. The variation of a gap between the magnetic recording medium and the magnetic sensor is detected as resistance variation of the second MR element. And the detected signal is serviceable as correcting the output picked up by the first MR element.

Abstract: Disclosed is an apparatus for controlling a motor unit including a variable-speed reversible main motor for driving a load and a subsidiary motor for driving a fan. The control apparatus comprises a temperature sensor circuit sensing the temperature of the main motor and generating a first output signal when the temperature of the main motor exceeds a first predetermined level, a second output signal when the main motor temperature exceeds a second predetermined level higher than the first predetermined level and a third output signal when the main motor temperature drops to a level lower than the first predetermined level, and a control circuit connected to the temperature sensor circuit for energizing the subsidiary motor in response to the first output signal, deenergizing the main motor in response to the second output signal and deenergizing the subsidiary motor in response to the third output signal.

Abstract: A flat armature is manufactured by forming a given number of coils over a separatable winding frame, fixing their relative positions by putting adhesive tapes across the coils on the frame, removing the coils from the frame, arranging a group of coils on a plane so that it will form a ring configuration, equipping the coils with a commutator, and moulding the coils equipped with the commutator with resin.