Abstract: A point-of-sale credit card verifier for checking the validity of cards, such as credit cards, comprises means for non-destructively storing information on invalid credit cards for comparison with information which is read from a card presented for use. The information on invalid credit cards is transmitted by signals embedded in a VHF stereo radio broadcast from a broadcast station which is received by a VHF receiver/demodulator. A credit card sensor and control maintains the verifier switched off unless a credit card is to be read. The verifier is switched on when information is about to be broadcast from a broadcast station. The verifier operates quickly and independently of telecommunications networks.