This circuit was found in an American documentation from the 1980s. The circuit combines filters of different types in a single structure, each of which can be programmed for a frequency.
This traditional circuit with the 555 was found in a 1984 documentation. In this oscillator, the...
This circuit was obtained in a publication for radio amateurs of 1977. It is used to reduce the...
This LED indicator circuit uses an LM339 comparator. The circuit was found in the January 1995...