| 摘要 |
PURPOSE:To improve the speed controllability by additionally providing another varistors at both ends of a resistor connected in parallel with a motor when controlling the motor incorporated with the varistor as a spark cancelling of a brush commutator. CONSTITUTION:A varistor 3 is incorporated in a micromotor A for preventing a spark or a noise of a commutator. It is then connected between a power source Vc and a terminal 1, a plurality of transistors Tr1 are connected between terminals 1 and 2, a parallel circuit of a resistor RT and a varistor 30 is provided between the power source Vc and the terminal 3, a transistor Tr2 is connected between the terminals 3 and 2, the Tr1, Tr2 are controlled by the difference between the partial voltage and the reference voltage Er between the terminals 1 and 3 to control the speed of the motor A. Accordingly, the unstable range of controlling the speed due to the influence of the varistor 3 provided in the motor A can be compensated by inserting the varistor 30, thereby improving the characteristics. |
