By analyzing and researching on capacitive liquid level sensor

a new type of capacitive array liquid level sensor is designed.The principle and design scheme is introduced.One electrode of capacitance is designed to array structure

another is shared.A tiny capacitance detection circuit based on the principle of charging and discharging is selected.SCM STC89C52 is used for controlling the gating of tiny capacitance

data acquisition and processing.The liquid level is calculated and converted to current signal of 4～20 mA.Experimental results show that the non-linearity and precision of the liquid level sensor approach 0.3 %FS

zero output is stable.It has the advantage of little drifting

low temperature influence

and zero temperature drift is less than 2×10-5FS/℃.