| 摘要 |
PURPOSE:To enable performing always a stable constant-speed operation by connecting a transistor with both ends of one side of a voltage divider circuit for setting a rotational speed and by turning ON and OFF said transistor to change a speed. CONSTITUTION:If a switch SW is closed, a transistor Q is turned OFF and a low speed operation is performed at a uniform rotating speed to be set according to a ratio of a resistance RT, variable resistances R1, R2 and a resistance R4. Also, if a switch SW is opened, the transistor Q is turned ON and the resistance R1 is short-circuited so that a high speed operation is performed. In this case, a base emitter voltage VBE acts upon a terminal S of a speedcontrolling IC2. This voltage VBE acts so as to prevent a variation of rotating speed of the motor 1 due to a change in the environment and temperature, Therefore, a constant-speed rotation is possible also in case of a high-speed revolution.
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