Spinning speed measurement - in false twister using resonance circuit to give output suitable for digital frequency meter
As the rotary tube section of a mon- or bi-galette false twisting machine spins, a scatter field is developed which is detected by a coil and a current induced. An amplifier with a resistance and condenser at its input form a resonance circuit with a basic frequency matching the basic frequency of the scatter oscillation, allowing a digital frequency meter to record the speed up to 750,000 rpm.