An instrument for measuring speed fluctuations and a method of calibrating such instruments
A Swindells · Journal of Scientific Instruments · 1953
An a.c. tachogenerator followed by amplifier and filter equipment has been used to measure fluctuations in low rotational or linear speeds. The sensitivity is such that speed fluctuations in the frequency range of 10-60 c/s and amplitude 0.1 rev/sec can be measured directly or 0.03 rev/sec with an auxiliary amplifier. The load imposed on the measured system is low. A new method has been devised for the calibration of the instrument. A differential gear box summates a steady speed and a sinusoidal oscillation, and the instrument is calibrated on the known output velocities of the differential.