This good power amplifier, a few tens of watts, is part of an article in the December 1972 Radio Electronics magazine. The power supply must be symmetrical with at least 3 A.
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...