| 摘要 |
PURPOSE:To drive a motor at a stable rotating speed even if a supply voltage drops by inserting a parallel connection unit of a diode and a transistor switch between a switching control circuit and an earth, and closing the switch when the supply voltage is the prescribed value or larger. CONSTITUTION:In a circuit for controlling the power supply of a motor 1 by a switching control circuit 2 which has a plurality of transistors, a parallel connection unit of a diode D and a transistor switch Q5 is inserted between the control circuit 2 and an earth. Means for monitoring the supply voltage Vs is provided to close the switch Q5 when the voltage Vs is the prescribed value or higher, thereby shortcircuiting the diode D and turning OFF the switch Q5 when the voltage Vs is the prescribed value or lower. Thus, when the voltage Vs is low, it can be shifted to a high level by the diode D, thereby stably controlling the motor 1. |
