This reflection IR sensor is a simple plastic housing with two elements - an IR LED and an IR phototransistor. You can control the IR LED and turn it on to bounce the IR objects to determine their reflectivity. White and light-coloured objects bounce the light so that you can detect it. Black and dark objects absorb infrared light so that it is not detected. Similarly, if something does not interfere with the sensor, it will not trigger either.

These sensors are useful when you want to detect if something has passed through the sensor, or a very simple manual sensor. If the encoder wheel has black and white stripes, the photodetector is fast enough to indicate the number of revolutions per minute.

Comes with a 470 ohms resistor (to polarize the IR LED) and a 10K resistor that you can use as a pull-up resistor for the phototransistor. The sensor is user-friendly and easy to weld on a bredabord.

This works best when you detect a light-colored object at a distance of about 5 mm - 2 to 10 mm worked quite well, but your results may vary depending on the brightness of the LED, the brightness of the object, etc.

Features

    15mm x 18mm x 5mm / 0.6" x 0.7" x 0.2" x 0.2
    Weight : 1g

Documentation

OptoreflectorConnection diagram for example, pin 13 is the LED control pin, pin 9 is the sensor input.