Natural resonance frequency measurement by magnetostrictive bar - vibrates longitudinally by oscillations induced in coil coupled to bar

摘要

The measurement apparatus determines the natural resonance frequency of a magnetsatrictive bar vibrating longitudinally. A coil, coupled to the bar (13), is alternately connected to an oscillator (21) and a measurement circuit, during periods P and Q respectively, this being repeated periodically. The oscillations induced in the coil are passed to a first gate circuit (15) which passes them on only during the periods Q. A frequency multiplier (19) receives the oscillations from the gate circuit (15) and passes them to a second gate circuit (10) which only passes them on during a predetermined fraction R of each period W. A display counter (7) receives the oscillations from this gate circuit (10) and operates during a time period defined by a time base (2) stabilised by a quartz oscillator (1). This time base (2) controls the periods P, Q and the fraction R.