Abstract: A self-calibrating photoelectric control system for use in a checkstand to control the starting and stopping of a conveyer belt utilized to move products closer to a checkout clerk. The self-calibrating photoelectric control system including a light source for emitting a light beam having an intensity, a photoelectric sensor for receiving light from the light source and for generating an output signal when the received light is equal to or greater than a light-state threshold of the photoelectric sensor; and a calibration circuit for automatically calibrating the sensitivity of the photoelectric control system to partial beam breaks after occurrence of any one of a plurality of predefined events. The calibration circuit is operative for performing a calibration process which adjusts the intensity of the light beam emitted by the light source such that the intensity is slightly greater than the light-state threshold of the photoelectric sensor.