| 摘要 |
PURPOSE:To obtain a drive controlling circuit for a DC motor without loss of wasteful power at the ordinarily rotating time by supplying a control signal through resistors of different resistance values to two transistors connected in Darlington connection. CONSTITUTION:When a control signal of high level is supplied to an input terminal 3, most of the control signal becomes the base current of a transistor Tr5 through a resistor R4 of small resistance value, thereby conducting the transistor. At the starting time, the starting current larger than the collector current corresponding to the base current flows. Accordingly, the voltage between the collector and the emitter of the Tr5 operating as a resistor exceeds approx. 0.7V, thereby conducting a transistor Tr4. Thus, the emitter current of the transistor Tr4 is supplied to the base of the transistor Tr5, thereby compensating for the starting current. Since the motor current is reduced in the same degree as the collector current of the transistor Tr5 at the ordinarily rotating time, the voltage between the collector and the emitter of the transistor Tr5 becomes substantially 0V, thereby allowing the transistor Tr4 to become OFF. |
