This 1970s RCA circuit can be triggered by light or dark, depending on how the LDR is connected. The controlled load depends on the triac.
In this circuit of an American documentation of the 90s, when the light is cut, we have the...
The circuit shown was found in a 1995 documentation. This circuit is powered by a voltage of 6 to...
This simple regulated power supply was found in a 1977 documentation. The zener diode determines the...