Found in Motorola documentation from the 90s, this circuit makes use of a triac from that time. The circuit is for the 110 V mains but can be modified for other grid voltages.
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...