A card is provided, such as a credit card or security card, that may transmit information to a magnetic stripe reader via a magnetic emulator. The emulator may transmit the information serially in order to reduce the amount of circuitry needed to emulate a particular block of information. Additionally, for example, a serial encoder may send any amount of information through a single emulation segment. Such a magnetic emulator may be provided on a credit card. A dynamic credit card number may be provided by, for example, coding a number with a different coding scheme for different periods of time. The magnetic emulator may be utilized to transmit a particular coded number for a particular period of time. In this manner, a dynamic credit card number may be provided such that to help secure, and progress, a payment transaction.