| 摘要 |
A coin-validating arrangement including a coin guide path and a sensing coil disposed adjacent said path, the coil being part of a tuned circuit coupled into a negative feedback path of an amplifier whereby to produce a phase shift sufficient to result in positive feedback and oscillation in said amplifier in the absence of a correct coin at the region of said path adjacent said coil, the tuned circuit being so arranged that on passage of a correct coin past said region the oscillation is quenched or reduced in amplitude, a circuit being provided for detecting the quenching or amplitude reduction of said oscillation, and a threshold detector provided for responding to said detecting circuit and opening an acceptance gate for the said correct coin. |
