Using a common crystal diode and a 741, this circuit can be used to detect microwaves. The circuit is from old documentation and the switch selects the gains.
This is the basic configuration of a function generator with the 8038 integrated circuit (uncommon...
This filter for receiving audio in telegraphy was found in a magazine 73 for radio amateurs, in an...
This circuit amplifies VHF signals in the two-meter range and is very critical, especially...