Studying and Making A Portable Meter to Measure the Liquid-Level

The portable meter to measure the liquid-level uses the phase-locking IC 567 as the detecting device ,MCU 89C2051 as the main control device, battery to provide the energy. The theory ,the circuit, and the program is introduced. The advantages of keeping clear of the medium which is detected, being likely to detect low temperature medium, no movable component, longevity and so on can be obtained when using the ultrasonic to detect the liquid-level. The system’s price can be reduced and the ability to catch the ultrasonic can be improved with 567 as the detecting component of the ultrasonic. The more intelligent can be obtained when using the MCU to control the emission and receiving and to calculate the liquid-level after temperature compensating. The causes by the ultrasonic velocity’s variety and the delay of the 567’s output to bring the measuring errors is analyzed and the method to reduce it is by heightening the precision when adjusting the ultrasonic velocity and the delay is also put forward.