Found in an American publication from the 1980s, this circuit can be found in commercial sound equipment of the time. The list with the component values is given next to the diagram.
This circuit was found in an old documentation and can be implemented with BC549 transistors. The...
This mid-waveband receiver was found in a book on transistors from 1954. The antenna coil is of...
Old multimeters used a 22.5 V battery for high resistance measurements. If you have one, you...