| 摘要 |
PURPOSE:To enable to use the transistor of a low price by a method wherein a pulse-width modulated wave is provided in a trapezoidal form and the period of time in which two transistors are turned to OFF position simultaneously is provided by adding two transistors to be used for controlling of power supply. CONSTITUTION:The output of a pulse width modulating circuit 31 is converted into a trapezoidal wave through a trapezoidal wave generating circuit 32 and this is inputted to the common base of the two transistors Q4 and Q5. The reference potential terminal provided by the first power source 36 is connected to the common emitter of the transistors Q4 and Q5 and the trapezoidal wave and the reference potential are compared with. The output terminals of the transistors Q4 and Q5 are connected to the base of Darlington-connected transistors Q6-Q7 and Q8-Q9, and a DC motor 45 and a smoothing circuits 43 and 44 are connected to the emitter common point of connection of the transistors Q7 and Q9. As an OFF period is provided with the transistors Q6-Q9, no high-speed switching property will be necessary for the latter stage of transistors Q6-Q9. |
