| 摘要 |
PURPOSE:To set the variation in the rotating speed of a DC motor to the voltage of a power source substantially to zero by connecting a series resistor between the collector of a transistor for driving the motor and a ground point and connecting the series connecting point of the series resistor to the input of a comparator. CONSTITUTION:Resistors 13, 14 are connected in series between a common connecting point of collectors of transistors 6-8 for driving a DC motor, i.e., an output terminal B and a ground point C, and the connecting point of the resistors 13, 14 is connected to one input terminal of a comparator 12. The comparator 12 compares the voltage in response to the counter-electromotive force Ea of a DC motor 3 with a reference voltage Vref of a reference power source 10 to control the base current of drive transistors 6-8. In this manner, the variation in the rotating speed of the motor to the voltage of the power source can be set substantially to zero. |
