This super regenerative detector circuit was found in an English documentation from 1963. The coil is frequency compliant. The transistors are germanium of the time.
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...