(A) ;STABILIZED SYNTHETIC RESIN COMPOSITION

摘要

In a motor-driving system, the motor speed is controlled by a feedback signal derived from the difference in frequency and phase between a manually adjustable variable frequency and a rotational speed indicating signal. Frequency deviation of the manually adjustable frequency from a standard frequency is detected to energize a visual indicating device to indicate the magnitude of the frequency deviation and hence the motor speed deviation from a setting level. The direction of the frequency deviation is detected to indicate whether the motor speed deviation is above or below the setting level. The variable frequency is manually adjusted to vary the motor speed by noting the visual indication until null indication is obtained.