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.

Posted in Arduino Hacks Tagged adafruit wave shield, arduino, ultrasonic, ultrasonic distance sensor, wav shield ← Fabricate Your Own 7-Segment Displays Easy Capacitive Touch Sensors In Eagle → ...

The goal of this module is to teach students about the properties of sound and computing distance with an ultrasonic sensor. The program can also be used to measure the relative distance. This module ...

While Hiten Gautam's device made using ultrasonic sensors, buzzer, and LED light that gets power supply from a 5 volt adapter, you don't have to touch Sarthak Jain's doorbell to ring it.