This 9-pixel circuit has been implemented with 9 LDRs and can be coupled to a processing system for an elementary artificial eye. The circuit is from Radio Electronics, November 1986.
This preamp version uses BC109 transistors that are older versions of the current BC549 in plastic...
This circuit was found in a 1980s documentation, using a comparator from the time. The...
I found This circuit is in a documentation of transistors from 1958. It uses germanium PNP...