This circuit was found in an ancient American documentation. The power supply is not given, but we have the voltages used. The relay is sensitive type for high voltage.
This circuit with automatic gain control was found in the July 1988 issue of Radio Electronics magazine....
The microwave sensor of this circuit is a common ceramic capacitor. The circuit is from an 80's...
This receiver was found in an article in Electronics Now magazine in March 1994. The coils are...