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 can be installed inside a toy space gun to produce a “Phaser” effect. The circuit is from...
This circuit was found in a 1988 publication. The circuit is an alarm with interrupt sensors that...
The frequency in this circuit is adjusted by P1 and given by C1. Short pulses, as the ones...