Abstract: A measuring head is used to measure a yarn characteristic while generating a continuous signal proportional to variations in the measured characteristic. The signal is multiplied by an identical second signal obtained either from a second measuring head located downstream of the first measuring head a distance corresponding to a predetermined periodic interval of yarn length (L) or by a time-delay of the first signal corresponding to the periodic interval (L). The multiplication of the signal deviations occurring at the periodic intervals, should such be present, produces a strong output signal indicative of the yarn irregularities. This output signal can be used to interrupt operation of the yarn processing machinery.

Abstract: The speed of the friction drive drum is electronically controlled as a function of the thread speed. The apparatus allows winding of a precision wound package or a random wound package. The apparatus employs an electronic control unit which calculates a desired value signal for the speed of the drive drum as a function of the thread speed from a mathematical formula and compares this value to the actual value in order to obtain a correction signal for the drive of the drive drum. A similar calculation is also made for controlling the speed of the traversing thread guide shaft.