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 ...

To build this DIY buzz wire game, you'd need an Arduino Nano, a 9V battery, two LEDs (red and green), a buzzer, a seven-segment LED display, a shift register for the display, and resistors for the ...

Instead, it relies on an ultrasonic distance sensor to detect a hand (or foot) waved in front of the door. An Arduino Leonardo runs the show, sounding a buzzer when the ultrasonic sensor is triggered.