The OCB100CZ calibration board can also be mounted into existing equipment to enhance system reliability and consistency. Degradation of the LED and the phototransistor is compensated for each time the system is calibrated which provides a consistent output and years of reliable operation. The OCB100 series is designed to maintain the calibrated setting even if power is lost, thus allowing a faster startup without the need for calibration every time the device is powered up. The calibration procedure can be easily initiated at any time by momentarily grounding Pin 4. This allows the device to be remotely calibrated, even while mounted in equipment.