Review on 20-Piece IR Infrared Obstacle Avoidance Sensor Module + Arduino Smart Car Robot Raspberry Pi 3-Compatible Reflective Photoelectric Sensor by Joseph Mathis

I bought them for a robot lesson for my students. We ended up using a slightly different version of these sensors, where the IR emitter and receiver are in a common plastic housing (and have an analog output). These offer good value for money, but it takes a little work to get the most out of them. The transmitter and receiver are discrete, so their alignment with each other can make a difference in response and performance. So mount the device and then carefully bend the wires on the transmitter and receiver so they point where you want them. In our case, we ran black line detection and they worked best at a slight angle to the vertical. So move them around to see what works best for your use case. There is no harm in adding a photocell between the transmitter and receiver. None of them are enclosed in a small tube to protect them from parasitic sources of IR radiation. Finally, the potentiometer needs to be adjusted depending on the use case - distance, target reflectance, etc. The built in status LED is great - it only allows adjustment when power is applied (no software required). The digital output is active low (green LED on). Beware of Electrostatic Discharge (ESD) - we have destroyed some LM393 comparators (small black chip) and IR receivers with static electricity. In general they are cheap and effective; good for simple projects.