This indicator circuit used and game machines (arcades) to indicate that the machine is being shaken was found in NASA documentation. The circuit uses as a sensor a container with water and three sensors.
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...