The IR emitter LED emits infrared continuously. 2. When any object comes within the range, the infrared falls on that object and some amount of infrared reflects from that object. 3. Then the refected infrared sensed by the IR receiver LED. 4. The voltage across the IR receiver LED changes proportional to the amount of reflected infrared. 5. Then we compare the voltage with the predefined value by the LM358 comparator. 6. If the voltage crosses the predefined limit the output pin of the LM358 IC becomes high. Thus the IR proximity sensor can detect the presence of the nearby objects without any physical contact.