This experimental monostable CMOS circuit, activating an LED was found in a documentation from the 1980s. It is recommended to connect in series with the LED a limiting resistor of 470 ohms or more.
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...