Ultrasonic measuring circuit using sample and hold method

This paper presents the simple ultrasonic measuring circuit using sample and hold method. The proposed method is to measure the transit time of ultrasonic wave in fluid. The system consists of the pulse generator circuit, amplifier circuits, band pass filter, detector circuit, comparator circuit, timing circuit, saw-tooth generator circuit, and sample and hold circuit. The voltage output signal of the proposed technique is proportional to the transit time. The sugar solution with differential concentrations was measured in our experiment as an illustrative case study. Experimental results show that the proposed method can measure the transition time of the ultrasonic signal with satisfied sensitivity and good linearity.