Abstract: A card having two adjacent magnetic tracks is used as a substitute for coins in activating laundry machines and the like. The first track is a data track encoded with a security code and pulses indicating a number of future uses of the card. The second track is a timing track used for both reading and writing encoded with square wave signals having a rate greater than the data rate on the first track and having the assertive edge coinciding with the start of pulses on the first track to strobe the first track to determine whether pulses are a "1" or a "0". The system re-encodes on the first track as the card leaves the machine one less number of uses of the card than when the card entered the machine, energizes a relay to start the laundry machine, and punches the card to indicate one use. A noise suppressor prevents re-encoding noise from affecting reading second track signals. The system employs a counter which is disabled so that the re-encoding cannot occur when the card enters the machine.