Rotary variable resistor

A rotary variable resistor, comprising:

• a resistance circuit module, including:
• a circuit board, having a circuit arrangement portion and a terminal arrangement portion extending from the circuit arrangement portion;
• an output circuit, including:
• a brush contact port, located at the circuit arrangement portion, having an annular brush contact area defined by a central axis;
• and
• an output port, extending from the brush contact port to the terminal arrangement portion;
• three input circuits, each of the input circuits having a resistor contact end and an input port, corresponding resistor contact ends of the three input circuits being evenly annularly separated around the central axis, each of the input ports of the corresponding input circuits being extended from the corresponding resistor contact end to the terminal arrangement portion;
• and
• a resistance ring, centered at the central axis, annularly spaced to the brush contact port, contacting each of the resistor contact ends of the corresponding input circuits;
• a fixation frame, fixedly mounted on the resistance circuit module;
• a brush assembly, rotatably restrained by the fixation frame, bridging the annular brush contact area and the resistance ring;
• and
• a rotor shaft, connected with the brush assembly so as to drive the brush assembly.