This circuit uses a wire potentiometer, but the current is much more intense in the control thanks to the 2N3055 which must be mounted on a heat sink.
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...