This sensor circuit from a 1967 Ferranti documentation uses components from the era. The circuit can be used as a shield, although the integrated one used is unusual today.
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...