This circuit was found in a 1970 American publication. The FETs are power types according to the desired output current. The operational can be replaced for modern equivalents.
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...