This is an Arduino-based Proximity Sensor circuit wired using the popular HC-SR04 ... If everything goes right,you should see the burning eye of the red LED when there is no object in the safe-zone ...

Inside [Klaus]’ device is an Arduino Uno, an HC-SR04 ultrasonic distance sensor, ... He’d have got 3-4 sensors and a little LED/beep display to be placed on his dash. Report comment. Reply.