Textile machine yarn monitor - has electrically conductive sensor for electric registration of yarn presence and speed of travel

Using a resistance of a high ohm value the charge is measured as a current to determine the presence of a yarn and its speed of travel. The current led off the yarn by the sensor is passed into an input amplifier with a high ohm value. It is then filtered and passed through a further amplifier acting as a rectifier to a comparator. The registered signal is compared with a reference signal, and the difference between them is used to illuminate an indicator or trip a stop circuit on the machine. The reference signal is extracted from the measured signal by a deep pass filter or a high order filter. The design gives a rapid and positive indication of a yarn break, using simple circuitry, when working with high yarn speeds, without being affected by dirt.