Found in a 1924 publication, this 2-valve receiver has a speaker output. Power comes from several batteries. Information about the coils is given.
Found in documentation from the 1980s, this circuit applies to other 3-terminal voltage...
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
This very simple configuration produces the sound of a space gun or laser. The circuit uses common...