This circuit by Ferranti, in a 1967 publication, is intended for reading perforated tapes. The circuit uses transistors from the era that can be replaced by modern equivalents.
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...