| 摘要 |
<p>To test a coin, the latter is moved through the controlled alternating-current field of a sensing coil (11) and from the difference between a reference voltage and the measured oscillator voltage which is changed due to the influence of the coin (1) on the alternating-current field, a controlled variable is formed by means of a differential circuit (18) which variable corrects the measured oscillator voltage to the voltage ratio between measured oscillator voltage and reference voltage which existed before the beginning of the coin measurement, via an influencing element (14) influencing the output voltage of an oscillator circuit (12). The controlled variable is used as criterion in the testing of the coin in such a manner that it is determined by means of a monitoring circuit (20) whether this controlled variable has reached a value which is located between an upper and lower limit. <IMAGE></p> |
