Prototype was constructed & tested using “Arduino UNO-R3” board Sketch created,compiled & uploaded (to Arduino board) using Arduino IDE0022 Piezo-Speaker in the circuit is a “passive piezo-speaker”.

The set-up process is very simple, and best understood by referring the wiring diagram. If everything goes right,you should see the burning eye of the red LED when there is no object in the safe-zone ...

You'll need a DC piezo buzzer or siren, a 10k Ohm resistor, an NPN transistor, two nails, 4 AA batteries and a battery pack, and an extremely thin wire to act as the trigger.