| 摘要 |
A polisher has a polishing disc on a shaft driven by a brushless DC motor driven by a motor controller mounted spaced from the polisher and adjacent a ground fault interrupt circuit and a power plug. Power and control wires form a cord that provides communication between a speed control switch, and a speed set switch, mounted on a handle of a polisher housing, which is a magnetic field sensor responsive to a movable magnet. The speed set switch sends a signal to the motor controller either to maintain the current speed of the motor or to allow the speed of the motor to vary in accordance with the output of of the speed control switch. The speed control switch is a variable output switch which can be an optical potentiometer constructed by reflecting light from a light source off a reflective surface forming part of a spring loaded trigger.
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