If no obstacle blocks the path, the light disperses, and the receiver detects nothing. When an object enters the detection range, the light bounces back toward the sensor.
The LM393 comparator provides a stable, clean digital output signal.
[IR Emitter] --------> (Infrared Light Beam) --------> [Obstacle] | [IR Receiver] <------- (Reflected Light) <------------------+ | [LM393 Comparator] ---> Compares with threshold preset by Potentiometer | [OUT Pin] ------------> Drops to LOW logic state Fc 51 Ir Sensor Datasheet
int sensorPin = 2; int ledPin = 13;
The infrared emitting tube continuously shoots out a beam of high-frequency infrared light. If no obstacle blocks the path, the light
Smooth, glossy surfaces offer specular reflection, producing consistent detection. Rough, matte, or transparent objects scatter or pass light through, drastically hurting accuracy.
The black-tinted photodiode captures the reflected IR light. Its electrical resistance drops proportionally to the intensity of the received light. The black-tinted photodiode captures the reflected IR light
The FC-51 only provides a digital HIGH/LOW signal. It cannot tell you the exact distance to an object; it can only tell you if an object is within its threshold zone. If your project requires precise distance measurement, consider using an ultrasonic sensor (HC-SR04) or a Time-of-Flight (ToF) sensor.
This simple sketch prints "OBSTACLE!!" to the serial monitor when an object is detected.
| Parameter | Value / Range | Details | | :--- | :--- | :--- | | Model Number | FC-51 | | | Operating Voltage | 3.0V - 6.0V DC (Commonly 5V) | | | Current Consumption | ~23 mA (3.3V), ~43 mA (5.0V) | | | Output Type | Digital switching (0 / 1) | | | Active Output Level | LOW (0V) when obstacle detected | | | Inactive Output Level | HIGH (~Vcc) when no obstacle detected | | | Detection Distance | 2cm - 30cm (adjustable) | | | Detection Angle | 35 degrees | | | Comparator Chip | LM393 | | | PCB Dimensions | 3.1 cm (L) x 1.4 cm (W) | | | Mounting Holes | 3mm screw holes | |
The is a low-cost, highly efficient infrared (IR) obstacle avoidance sensor widely used in robotics, automation, and smart home projects. This comprehensive datasheet guide covers its technical specifications, working principles, pin configuration, and practical interfacing examples. Technical Specifications