TCRT 5000 is a highly sensitive IR reflective Sensor that has an IR lED and a Phototransistor in a common package. It is an ideal module for projects like Robotics, Position sensing, Detection of Reflective materials etc. Its range is 2-10 mm and best response range is 3 mm.
The Infrared Sensor has two parts. An Emitter and a Receiver. Emitter is the IR LED that has Anode and Cathode pins. A Current limiting resistor of 470 Ohms to 1K should be added in series with the Cathode of IR LED. Anode of IR LED should go directly to Vcc. The receiver is a Phototransistor with Collector and Emitter.A load resistor of 10K should be added to the emitter of Phototransistor and its Collector should go directly to the Vcc.
The Reflective sensor gives two types of outputs based on the intensity of the Reflecting IR rays falling on the Phototransistor. The Analogue out put is in terms of DC Voltage. That means, when the Phototransistor is not receiving the reflected IR rays, output is 0V and when the Phototransistor gets reflected IR rays, output voltage increases from 0V to around 3 V based on the intensity of the reflected light. The Reflective Sensor also has Digital output. That means, when the Phototransistor is not getting reflected IR rays, output remains in Logic 0 and when it gets reflected light, output turns to Logic 1.
A Test Circuit is give below. An LED is connected to the output of the Reflective sensor for visual indication. When there is no reflective surface in front of the sensor, LED remains off indicating Zero output ( Logic 0 ). When a reflective surface such as white paper is present in front of the sensor (around 2-5 mm distance ), LED turns on indicating High output ( Logic 1 )