Suggested by Texas Instruments in 1968 documentation, this circuit uses components from the era. Modern diacs and SCRs can be employed.
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...