Abstract:Aiming at the current problems in paper counting, an astable multivibrator was constituted by 555 timer, and a paper counting display device was designed. With paper sheets placed between two polar plates, the corresponding capacitance could be transformed to frequency and then the impulse frequency would be sent to STC89C52 and processed by it. Through the operation function of single chip computer, the number of paper sheets could be judged by fitting curve of measured data module. The number of paper sheets could be displayed by LCD 1602. The experimental results showed that the experiment device could realize some functions as self-calibration, short circuit alarming and paper sheets testing and so on. The error could be controlled less than one when the paper sheets were within 30 pages.