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 was found in a 90's Electronic Design. It takes advantage of the nonlinearity...
This sensitive Japanese mid-wave receiver from the 1960s has an output power of 45 mW and is...
This sensitive MW receiver was found in a publication of year 1958., The circuit uses germanium...