Coin verifying unit using oscillator coil - compares rectified oscillator voltage with reference voltage as coin falls through oscillator coil

摘要

The coin verifying unit, e.g. for a coin-operating vending machine, has the coin (1) forwarded through the constant AC field of an oscillator coil (11) with the rectified oscillator voltage during passage of the coin compared with a reference voltage, to obtain a control value. The latter is used to maintain the coil voltage constant via an adjustment element (14) and is supplied to a control circuit (20) which determines whether the control value lies between upper and lower threshold values. The time constant of the adjustment circuit is dependent on the velocity of the coin (1) such that the oscillator voltage during passage of the coin remains constant, while the control value for the control circuit (20) attains the highest possible amplitude.