This circuit is from the 1968 ARLL documentation. The MOSFET admits equivalent and the coil determines the operating frequency range being the plug type.
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...