This circuit was found in a 1965 General Electric documentation. It is intended for reception of the aviation strip, but inside an aircraft or nearby (which is now prohibited).
This commercial receiver from the year 1958 uses two AA cells as Power supply. The circuit is...
PIC18F “K40” Features Intelligent ADC with Filtering and Signal Analysis Capabilities Ideal for...
This circuit appears in similar versions on this site. This is from a Popular Electronics from the 80's. The...