This circuit is from a 1980s Motorola documentation. The circuit can be set to fire from 60 to 120 V DC or from 42 to 84 V AC. The circuit has a forehead button that activates an indicator lamp.
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...