This TTL time base for 60 Hz or 50 Hz can be used in instrumentation circuits or even with microcontrollers, serving as a precision shield. The circuit is based on 7400 NAND ports and two transistors.
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...