One aspect of the present disclosure can include an electronic signal processing system and method used in a control system (e.g., for hour meter functionality, intelligent start/stop functionality, etc.). The system can include a rectifier component to receive a voltage input from an operation source during use. The voltage input can indicate that an engine is running. The rectifier component to convert the voltage input to a positive voltage input. The system can also include a constant current component to receive the positive voltage input from the rectifier circuit and to control a current based on the positive voltage input. The system can also include an optical component to provide an output based on the current and to communicate the output to a microcontroller during use of the operation source. For example, electronic signal processing methods and apparatuses are also described.