Producing items onto a screen simply by touching the air is a marvelous thing. One way to accomplish this involves four HC-SR04 ultrasonic sensor units that transmit data through an Arduino into a ...

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.

The compact module helps us to test HC-SR04 modules quickly without a costly microcontroller setup (no code lines/solder smokes) and/or build an extremely portable minimalistic sonar device. I have ...