Here is light siren or siren ray. this circuit based of ic 555 timer. This circuit can be used as an anti-burglar alarm in certain rooms, such as cupboard, cupboard in the open when the light will hit the circuit, so the alarm will be activated. When no light falls on the LDR, the transistor is pulled high by the variable resistor. Hence the transistor is OFF and the reset pin of the 555 is pulled low. Due the this the 555 is reset. When light falls on the LDR, its resistance decreases and pulls the bases of the transistor low hence turning it ON. This pulls the reset pin 4 of the 555 high and hence enables the 555 oscillator and a sound is Produced by the speakers.