| 摘要 |
A control circuit providing pulse width modulated energization to a load from a d.c. power source has a pair of input terminals connected to the source and a pair of output terminals connected to the load. A potentiometer provides a variable magnitude control signal. A first transistor has the base terminal connected to the potentiometer. The collector terminal is connected through a first resistor to the positive voltage input terminal. The emitter terminals is connected to one of the output terminals. A second transistor has its base terminal connected intermediate the first resistor and the collector terminal of the first transistor. The emitter of the second transistor is connected to the positive voltage input terminal. The collector is connected through a second resistor to the one of the output terminals. A capacitor is connected in between the collector terminal of the second transistor and the base of the first transistor. A third transistor has the collector connected to the positive terminal and the emitter connected to the one output terminal. The base is connected intermediate the second resistor and the collector of the second transistor. The control circuit may be incorporated in a bridge circuit providing bi-directional speed control to a d.c. motor.
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