This is an Arduino-based Proximity Sensor circuit wired using the popular HC-SR04 Ultrasonic ranging module,used here for non-contact object detection purpose. The HC-SR04 module includes ultrasonic ...

Buy arduino, buy sound shield, buy distance sensor shield, plug into each other, burn example code, stuff components inside box. Not only is this not a hack but he might as well have just bought a ...

The sensors were home-built using ultrasonic capsules soldered into a custom board, ... PVC pipe, weights/pulleys, Arduino and the Radio key fob – were all bought for under 40 dollars.