An Improved Device of Detecting True and False Coin

Abstract

In order to reduce the loss of an automatic coin machine for using a 1-Yuan false coin, an improved device is designed by applying the eddy current nondestructive testing technology, which uses two distinct frequency signals to detect the information of coin. The device includes four modules: two LC oscillating circuits, signal processing module, microprocessor module and external control circuits. The detection algorithm selects two counting values under two distinct frequency signals. The low frequency circuit detects the information of the coin material, and the high frequency circuit detects the feature of the coin surface. The detection region of true coin is decided by the method of least square. The experiment shows that the device has the characters of stability, reliability and high accuracy.