| 摘要 |
PURPOSE:To control a rotational speed by obtaining a reference voltage proportional to the rotational speed of a DC brushless motor from the detection end of a bridge circuit and by comparing the voltage with another reference voltage and controlling a feed control transistor through the difference voltage between said voltages. CONSTITUTION:The output voltage of a constant voltage circuit 14 is divided by a resistance type voltage divider circuit composed of a series connection of resistances 21, 22 so that a reference voltage is obtained as the terminal voltage of the resistance 22. When a DC brushless motor varies in the number of revolutions due to load fluctuation, etc., an induced voltage generated in the motor changes and a voltage generated in a motor actuator also changes and the change is divided by resistances 18, 19 constituting a bridge circuit. Then, the divided voltage is compared with the reference voltage of a reference voltage source by an error amplifier 15 and the output of the amplifier is amplified by a transistor 16 and transmitted to a feed control transistor 17 to control the output current I. |
