Fritzing

LDR and 555 timer based light activated police siren

You can make a simple light activated police siren using 2 NE555 timers and light dependent resistor. Both timers are configured in astable mode and connected to each other. The timing of both timers make police siren. A simple LDR based light sensor is connected to the circuit to make it light activated police siren. You can get all the schematics and operating videos on buildcircuit.com