This is the receiver from the previous alarm system. The circuit is from Radio Electronics, April 1989, and has an LDR as the sensor. Optical devices should be used to improve performance.
This is yet another simple LED driving game circuit that appears in several other versions on this site....
We found this circuit in a manual of optoelectronics from Texas Instruments. In it photodiodes or...
This interesting circuit is from a 1988 documentation. It is a matrix of diodes that converts...