Loud 10-W Car Alarm Siren



This alarm generates square-wave output that sweeps down and up in frequency, producing force field of high-intensity sound inside car, building, or your other properties. In security application for example, this circuit can make a car thieve panics and decide to run before anyone catch his action. D1, C1 and R1 produce triangle waveform by shaping a square wave output of IC1.  If using sweeping alarm sound is prohibited by regulation, then C1 can be removed to provide legal two-tone sound as heard on old ambulance. The diodes are general purpose small signal silicon except D2 which is silicon rectifier rated 1 A at 50 PIV. This circuit can handle up to 10W depends on the horn loudspeaker. This circuit can be easily wired on a dot matrix  PCB, as well as on the printed one. Because the TIP30 transistor works in linear mode (when not fully driven for lower intensity), it probably need a larger heat-sink to avoid overheating.