Abstract: A device for measuring the transverse dimension, such as the diameter of a textile thread, comprises a light source, a linear array of optoelectrical sensors, a clock for periodically scanning the linear array, and electronic circuitry for evaluating the serial signals furnished by the linear array. The electronic circuitry comprises amplifying means, a limiter such as a Schmitt-trigger, and means for integrating the pulse amplitudes furnished by the linear array over a plurality of scanning periods or cycles. Further, means are provided for automatically controlling the response of the electronic circuitry in inverse proportion to the averaged output of the integrating means.

Abstract: The invention is concerned with an electronic device for testing and controlling the clearing action of an electronic yarn clearer. The device comprises an individual fault measuring circuitry connected to the yarn sensing head of the yarn clearer for detecting yarn faults such as thick and thin places, and selector means for separating the non-tolerable faults from the rest. By comparing the output of the device and the output of the yarn clearer, the non-tolerable faults which have not been cut-out by the yarn clearer are detected. It is possible to eliminate also the latter faults from the yarn by actuating the severing device of the clearer.