| 摘要 |
The coil used in the measurement is supplied with a current pulse at the instant, determined by a light gate, when the test coin (4) is near the coin. The voltage swing in the coil produced by the coin is compared with a reference voltage when there is no coin present. In the side walls of the coin channel (5) there are two holes (3, 3`), forming shutters for the light transmitter or LED (24) and the light receiver or phototransistor (22). These are designed to measure the instant a coin passes the coil.
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