| 摘要 |
<p>PCT No. PCT/GB97/00229 Sec. 371 Date Oct. 16, 1998 Sec. 102(e) Date Oct. 16, 1998 PCT Filed Jan. 24, 1997 PCT Pub. No. WO97/29460 PCT Pub. Date Aug. 14, 1997A coin diameter measuring circuit uses a pair of coils coupled in the feedback path of an oscillator so that the oscillator frequency depends on the inductances of the coils and the mutual inductance therebetween. The coils are switched between aiding and opposing configurations when the coin passes between them, the oscillator frequency in each configuration is measured, and the difference between the frequencies is determined to provide an indication of the mutual indictance of the coils and, thus, the diameter of the coin. Preferably, the diameter is determined by the difference between the measured mutual inductance with the coin present and the coin absent.</p> |
