Fc 51 Ir Sensor Datasheet _verified_ May 2026

is a popular, low-cost infrared (IR) obstacle avoidance sensor module commonly used in robotics and DIY electronics for proximity detection. It operates by emitting an IR signal and detecting the reflection from nearby objects. Technical Specifications

The module is designed for simple "object vs. no object" detection rather than precise distance measurement. Specification Operating Voltage 3.0V – 6.0V DC Current Consumption ~23 mA at 3.3V; ~43 mA at 5.0V Detection Range 2cm – 30cm (adjustable via potentiometer) Detection Angle LM393 Voltage Comparator Output Type Digital (HIGH/LOW) Board Dimensions ~3.1cm x 1.4cm (PCB) Pinout and Indicators

The module features a standard 3-pin male header for easy interfacing. Fc 51 Ir Sensor Datasheet

FC-51 IR Proximity Sensor - am I doing it wrong? - Arduino Forum

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Onboard Components

• IR Transmitter (TX): An Infrared LED that emits invisible light.
• IR Receiver (RX): A photodiode or phototransistor sensitive to infrared light.
• LM393 Comparator: Compares the analog signal from the receiver with a reference voltage to provide a clean digital output.
• Potentiometer: A small blue screw terminal used to adjust the sensitivity (detection range).
• LEDs:
  • Power LED: Lights up when the module is powered.
  • Status LED: Lights up when an obstacle is detected (Output is LOW).

Part 4: Output Logic and Operation Modes

Understanding the output logic is crucial for programming. The FC-51 outputs a digital TTL signal. By default (most modules), the logic is: is a popular, low-cost infrared (IR) obstacle avoidance

• No object detected: Output = HIGH (Vcc, ~5V or 3.3V)
• Object detected within range: Output = LOW (GND, ~0V)

However, some variants (or if you modify the comparator circuitry) can invert this behavior. Always test with an LED and resistor first.

7. Typical Applications

• Line-following robots (using two FC-51 modules)
• Obstacle avoidance robots
• Contactless proximity sensing (e.g., touchless faucets)
• Edge detection for automated guided vehicles (AGVs)
• Simple presence detection (e.g., trash can lid opener)

7. Interfacing the FC-51 with Arduino (with Code Example)

Now, let's put the datasheet knowledge to practice. Below is a complete example of connecting the FC-51 to an Arduino Uno and using the digital output to turn on an LED or print a message to the serial monitor. Onboard Components

When to use—and when to choose something else

• Use FC-51 when you need a cheap, easy-to-integrate proximity or line sensor for controlled indoor hobby projects.
• Avoid it in outdoor, safety-critical, or high-precision contexts. For those, consider modulated IR with matched demodulation, LiDAR/ToF sensors, or ultrasonic sensors with known, robust performance envelopes.

Standard Pinout (Version A – Most Common)

| Pin Number | Name | Function | | :--- | :--- | :--- | | 1 | OUT | Digital output signal (HIGH = no object, LOW = object detected) | | 2 | VCC | Power supply input (3.3V or 5V) | | 3 | GND | Ground (0V) |

8. Connection Example (Arduino)

int sensorPin = 2;
int ledPin = 13;
void setup() 
pinMode(sensorPin, INPUT);
pinMode(ledPin, OUTPUT);
Serial.begin(9600);

void loop() 
int sensorValue = digitalRead(sensorPin);
if (sensorValue == LOW)  // Obstacle detected
digitalWrite(ledPin, HIGH);
Serial.println("Obstacle!");
 else 
digitalWrite(ledPin, LOW);
delay(50);