This simple power supply circuit triggers when the light on the LDR reaches the level set on the potentiometer. The circuit is from an Electronics Now from July 1995.
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...
We found this circuit in a Radio Electronics from January 1967. The SCR is already the C106, which...
This power source with silicon diodes at a time when valves were still used was found in Radio...