Found in a 1967 RCA documentation, this AC power grid contactor can be fitted with modern equivalent components. The SCR and the diodes must be according to the load current.
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...