| 摘要 |
PURPOSE:To enable the effective operation of a DC motor even if the voltage of a power source becomes low by connecting resistors in series across the motor and connecting the common connecting point of resistors to the noninverting input terminal of a comparator. CONSTITUTION:A transistor 3 forming a current mirror circuit with a transistor 2 is connected to a DC motor 1. Resistors 11, 12 are connected in series across the motor 1, and the common connecting point C of the resistors 11, 12 is connected to the noninverting input terminal of a comparator 7. The noninverting input terminal of the comparator 7 is connected to the connecting point of the transistor 2 and a positive temperature coefficient resistor 5 through a resistor 13, and is connected to a constant-current circuit 20. In this manner, since the input voltage of the comparator 7 is fallen in the input voltage operating range of the comparator 7, the effective operation of the motor can be performed even if the voltage of the power source becomes low. |
