| 摘要 |
PURPOSE:To make self-reversing electrically possible and to materialize cost reduction of a DC motor, by providing electric normal and reverse rotating function and electric speed control function to the motor. CONSTITUTION:If a switch 3 is set on A side, PNP transistors 5 and 7 will be conducting and a DC motor 9 rotates normally. If a switch 3 is set on B side, PNP transistors 6 and 8 will be conducting and the DC motor 9 rotates reversely. Resistance bridges are composed of a resistance 4, an inner resistance Ra of the DC motor 9 and resistances 16 and 17. By a voltage comparator 15 reference voltage 19 and counter electromotive voltage of the DC motor 9 are compared to control the rotating speed. Thus, a unit can be obtained that controls the normal and reverse rotation and the speed of a small-sized DC motor electrically at the same time. |
