The Study And Development Of Liquid Density Meter

In this dissertation, the vibratingtube density measuremeflt scheme is ProPOsedby StUdying liqud measurement methods, and the liquld densimete is construCted. Ustyle quartz tube is the kernel of the transducer, the paper discusses the designprinciples of the tube. The author designed self excitatCd posihve feedbak circuitwhich is made uP of gathering the signals, amplification, filtering waves, shiftingPhases, keoping amplitude excitation. On the effeot of self excitated POsitive feedbackcircuit, the tube oscillates in it's mechanical ndural frequency. To eliminate theinduence of environmental temperature and increase the stability of measurement, athennostat based on fhaz controller is designed. Digital sAnulation shows thecontrOller to be more adaptive than PID. The deVloped aPPaatus has passed the testof National Institthe of MCtrology...