The circuit on this page is for a simple light detector circuit board that has 8 detectors that can be used with visible or infrared light systems. The detectors use LM339 voltage comparators as the active element.
Phototransistors or CdS photocells can be used as sensors for this circuit. If phototransistors are used the circuits can also be used as infrared light detectors. These detectors can be used as part of other light detector circuits shown on other pages at this site such as these Light Activated Detector Circuits at this site.