This Reflective IR Sensor comes in a simple plastic casing with two key parts: an IR LED and an IR phototransistor. You can switch on the IR LED to bounce infrared light off objects and measure their reflectivity. White and light - colored objects will reflect the light, allowing the sensor to detect them. In contrast, black and dark - colored items will absorb the IR light, so they won't be detected. Also, if there's nothing in front of the sensor, it won't activate. These sensors are extremely useful. They can detect if something has passed by, work as a basic hand - detector, or function as a rotary encoder when used with an encoder wheel having black and white stripes to measure RPM. They're a top choice for line - following robots because they're tiny, easy to solder, and can be placed close together. The sensor is compact, breadboard - friendly, and simple to solder. It even has helpful markings on the plastic to show which side is the LED and which is the phototransistor output. The pack includes 5 sensors, but it doesn't come with 470Ω - 1KΩ resistors for the Infrared LED or a 10KΩ output pull - up resistor. It works best when detecting light - colored objects about 5mm away, though a range of 2mm to 10mm can also work, with results varying based on LED brightness and object shininess.
Using these sensors is quite easy. First, if you want to detect an object's reflectivity, turn on the IR LED. When an object passes in front of the sensor, it will react based on the color of the object. For using it as a rotary encoder, attach it to an encoder wheel with black and white stripes, and it will measure the RPM. If you're building a line - following robot, simply solder the sensors close together on your circuit board. When it comes to wiring, remember that the pack doesn't include the necessary resistors. You'll need to add 470Ω - 1KΩ resistors for the Infrared LED and a 10KΩ resistor for the output pull - up. Keep in mind that the sensor works best at around 5mm from a light - colored object, but you can experiment within the 2mm to 10mm range. To maintain these sensors, keep them away from excessive heat and moisture. Also, avoid scratching the plastic casing as it has useful markings that help you identify the LED and phototransistor output sides.
