This circuit was found in Delco documentation from 1965. The transistor is of the time, but any current power PNP with at least 500 mA collector current and 100 V collector voltage can be used.
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...