METHOD OF AND APPARATUS FOR ASSESSING COINS

摘要

The invention relates to a coin validator for use in a micro-processor controlled call coin box telephone instrument. The validator comprises first and second coil sets driven by square wave interrogation pulses. The arrangement of the coils is such that when a coin is in the coin-runway of the call coin box, one coil pair is used to interrogate the coin in the runway while the other coil pair provides environmental conditions apertaining to the runway. The information generated by both coil sets is combined thereby compensating for environmental changes and drift. Information pertaining to the relative response times of the secondary coils is then used to determine coin validity.