This sensitive two-transistor circuit was found in the June 1965 Radio Electronics magazine. The circuit has low drift and uses an analog instrument. The input resistance is high.
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...