| 摘要 |
<p>A coin validation system includes a plurality of coils (21,22) in an oscillating circuit operable to create a substantially homogenous three dimensional electromagnetic field. The oscillating signal is converted into a square wave signal from which the maximum oscillating frequency on passage of a coin between the coils (21,22) is determined to obtain a measure of coin diameter. A peak detector is provided and an indication of coin composition is obtained from the lowest measured peak. The system can enable detection of coins in free fall through the coils.</p> |
