This circuit is from the time when cars used contact breakers. This 80's version measures the dwell angle of the contact breaker for dwell adjustment using an era integrated circuit, the LM3917.
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...