This bargraph circuit was found in the January 1986 issue of Radio Electronics magazine. It is based on the well-known LM3914 and has two of them in cascade driving a good number of LEDs.
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...