DIY IR Proximity Sensor

When you need object detection for a robot or other electronics project, an IR proximity sensor can be a great solution. These devices are probably most common as a small PCB, and after using one for his automatic hand sanitizer, “New Pew” decided to investigate their operation further. This resulted in building his own proximity sensor using an IR emitter and receiver, along with a pair of BC547 transistors.

When sufficient IR light is reflected back to the receiver, it signals the first transistor, which in turn signals the second transistor to provide power to a green LED. This lights up to indicate that something is around. There’s no sensitivity pot, but if needed the emitter/receiver sensor can be bent so as to avoid false readings. A 100 ohm resistor is added to the positive leg of the LED to avoid sending it excessive current, and powered is supplied by a 9V battery.

The sensor is beautiful in its simplicity, and instead of using a breadboard or similar means, the whole thing is soldered together as a sort of freeform circuit. Perhaps several of these could be used together for a full robotics setup, or one could even be integrated into a revised non-contact hand sanitizer!