This circuit is one of many that can be found in this section using the 555. This circuit was found in old American documentation being applied to cars that use contact breaker.
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...