| 摘要 |
PCT No. PCT/GB91/00680 Sec. 371 Date Nov. 6, 1992 Sec. 102(e) Date Nov. 6, 1992 PCT Filed Apr. 29, 1991 PCT Pub. No. WO91/17527 PCT Pub. Date Nov. 14, 1991.A method and apparatus for testing coins is described. In particular, the resistance introduced into a tuned circuit by the proximity of a coin while it is moving past an inductor of the circuit is determined by changing the amount of phase shift present in a feedback path associated with the circuit and measuring the resulting change in frequency of oscillation, which is dependent upon the resistance in the tune circuit.
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