This circuit that emits siren sound can be used in a fire alarm. We found it in an old American documentation. The signal must be applied to a good audio amplifier.
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...