This CW circuit was found in a Radio Amateur Today from the 890s. The CMOS circuit must be powered by an isolated source and has different dash and dot timings.
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...