An exercise repetition sensor comprises an electricity generator, such as an electricity generator, which is coupled to an exercise system, where the electricity generator is capable of sensing exercise movements of any size or intensity on the exercise system. The electricity generator can be based on a number of electrical, magnetic, or optical sensing principles. For example, an electricity generator comprising an electricity generator includes a spindle that is coupled to one or more parts that move in proportion to an applied force. The voltage-generator generates an electrical current as the spindle moves, and sends the electrical current to an electronic display interface. In one embodiment, the voltage-generator sends a positive direct current through one of two circuit wires to the electronic console, such that the electronic console can immediately identify that the user has performed an exercise repetition.