| 摘要 |
PURPOSE:To reduce a load to be applied to a drive transistor by so switching the voltage of a power source to a state as to be supplied directly to the transistor or to a state as to be supplied to the transistor through a predetermined voltage drop, and varying a motor supply voltage in response to the variation in a load. CONSTITUTION:When a control signal S1 is an L level, the output of an inverter 32 is an H level, and hence a relay controller 31 is not turned ON, and a relay contact 37 is OFF. The output of fan inverter 33 is an L level. In this case, since a predetermined voltage clamped by a Zener diode 32 is supplied to the base of a transistor 36, the transistor 36 is turned ON, and a power source voltage of voltage drop by the transistor 36 is supplied to the transistor Q1 of a drive transistor 2. On the other hand, if the signal S1 is an H level, the output of the inverter 32 is the L level, and the contact 37 is ON. The transistor 36 is self-biased, and a voltage Vcc is supplied directly to the transistor Q1 of the transistor 2. |
