Using 4 tubes, this 1924 receiver combines new technologies as an intermediate frequency stage that was already beginning to appear. Listening is via phone and battery power.
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...