Found in RCA documentation two years 70, this circuit triggers an incandescent lamp at dusk. The circuit uses an LDR 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...