Abstract: A self-contained time cycled security code activation system for controlling a piece of power equipment includes a keyboard via which an activation security code is input into a microprocessor. The microprocessor controls an activation relay which selectively controls the equipment and it has stored therein a plurality of security codes which are time cycled via a real time clock. Thus, for example, a different security code can be automatically cycled for each lease or purchase payment interval, such as monthly. The lessee or purchaser is given only the security code or codes for which payment is current. A pair of LED's indicate the keyboard status, including an optional grace period during which the equipment remains operable. If the next month's code is entered during the grace period, the equipment remains operable for the next 30 days. In a second embodiment, the activation code is also a constant security code which is required to be input each time the equipment is used.