This circuit is from a 1977 Radio Shack manual. The photocell is an LDR and the operational one is a 741. Components with non-standard values can be approximated.
This circuit was found in the February 1983 issue of Radio Electronics magazine. It is a 4-digit...
The circuit shown consists of a single switched power supply. We found it in English...
This logic level indicator was found in a 1988 documentation. The circuit can be used with both...