| 摘要 |
A motor-controlling apparatus is disclosed, wherein the signal generated by the Hall element located near the rotor of a motor is amplified twice, first by an input amplifier and then by an output amplifier, thus producing two drive pulse signals which are out of phase and having a 180 DEG duration. These signals are supplied to the motor coils of the motor and also to comparators connected at the output. The output currents of the comparators are thus combined, forming an output current, which is delayed and then converted into a voltage. This voltage is applied to the inverting input terminal of a two-input amplifier constituting a feedback circuit. A constant voltage is applied to the non-inverting input terminal of the two-input amplifier. The two-input amplifier generates a bias current, which is fed back to the output amplifier, thereby reducing the changes in the speed of rotation of the motor which result from the variation of the load on the motor. The constant voltage applied to the non-inverting input terminal of the two-input amplifier, or the resistance of the resistor connected to the inverting input terminal of the amplifier is changed, thereby to drive the motor at two or more different speeds of rotation.
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