This circuit with the 555, was obtained in a 90s American documentation. The signal must be applied to a good amplifier. The sound is similar to that of a police siren.
This circuit was found in the Electronics Experimenter Handbook of 1961. The circuit uses door...
The basis of this circuit is a National Semiconductor operational amplifier that functions as a...
This two-transistor amplifier can be used as power stage for intercom, experimental receivers,...