| 摘要 |
An inverting amplifier (6) circuit generates a comparison voltage by comparing a smoothed voltage (V6) of a voltage across a semiconductor switching element (TR1) and a setting voltage (V0) that is generated by means of a voltage setting volume. An operational amplifier (5) generates a drive signal (V5) by comparing the above comparison voltage (V3) and a triangular voltage (V4). Negative feedback is effected so that the setting voltage becomes equal to the smoothed voltage (V6), which is inversely proportional to the rotation speed of a DC motor. <MATH> |
