This high sensitivity sensor was found in a 1967 General Electric SCR manual. The circuit admits equivalents by triggering a load according to the used SCR.
This circuit that uses two LDRs as sensors was found in Radio Electronics magazine from November 1961....
Indicated by Popular Electronics to be used with a car headlight, this circuit can also have...
This circuit was obtained in a 1982 English magazine. It is a regulator for outputs between 1 and...