We found this circuit in a Motorola manual. The circuit has the capacitor charging at 15 to 30 V, then discharging through the coil and generating a voltage that reaches 500 V for the spark plugs.
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...