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.

Hi, I'm Bill. I'm a software developer with a passion for making and electronics. I do a lot of things and here is where I document my learning in order to be able to inspire other people to make ...

With a standard old HC-SR04 ultrasonic sensor, an audio module and a servo to drive a custom gauge needle he’s made a device which can warn people around you if they’re too close for comfort.