| 摘要 |
PURPOSE:To reduce current concentration on the starting of the motors, and to eliminate the danger of the simultaneous starting of a plurality of the motors by turning the second motor when the speed of revolution of the first motor reaches a fixed value or more. CONSTITUTION:A signal (a) of frequency proportional to the speed of revolution of the motor 1 detected by a tacho-meter 1a is transmitted over a monostable multivibrator 6, and a pulse signal (c) of fixed pulse width is obtained in the repetitive frequency of the input signal (a). Voltage Va is generated by a frequency-voltage converter 7 from the signal (c), and transmitted over the voltage comparator 10 of a speed detecting circuit 14. When voltage Va reaches reference voltage VRFF or less, output voltage Vb reaches a ''H'' level, the reset terminal R of a FF 18 is triggered and a Q output reaches a ''H'' level, and a driving amplifier 9 is supplied with the voltage Vc of the FF and a capstan motor 3 is started. |
