Using 555 timer to drive flashing / blinking LED and beeping siren sound - this is another simple circuit that has quite plenty of application in the real world.
1 x 555 Timer chip
1 x 680 uF Electrolyte capacitor
1 x 150 Ohm resistor
1 x buzzer
1 x LED
1 x 9 Volt battery optional and 5 Volt also can be used.
1 x Breadboard