With an output power of 1.5 W under a 12 V supply, this circuit makes use of transistors that are still common today. Power transistors must be mounted on heat sinks.
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...