This windshield wiper timer was obtained in an 80's Hands On. The transistor can be the BC548 and the relay is 12 V sensitive. The time is set to R3.
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...