Using the 741 this basic circuit was found in the November 1973 Radio Electronics magazine. The power supply must be symmetrical. The components can be recalculated for other frequencies.
This line protector circuit was found in a 2002 documentation, but it is totally current and...
This antenna for the frequencies 146 or 440 MHz was found in a magazine 73 for Amateur Radio of...
With this circuit it is possible to increase the output voltage of a 7812 regulator. The circuit...