Fc 51 Ir Sensor Datasheet Hot Jun 2026

The IR LED emits a 38kHz–56kHz modulated signal (though many clones use continuous IR). The phototransistor detects reflected IR from an obstacle. The LM393 comparator compares the phototransistor’s voltage to a reference voltage set by a (blue box on the board). When reflected IR exceeds the threshold, the output goes LOW.

: If the module is hot to the touch, check for a reverse polarity connection (VCC/GND swapped) or a short circuit in your wiring.

≥ 20mA (Typically around 30-50mA during active detection)

❌ Digital output only – cannot measure exact distance ❌ Susceptible to ambient IR (sunlight, incandescent light) ❌ Detection distance varies with target reflectivity ❌ May require physical LED alignment for maximum range fc 51 ir sensor datasheet hot

The reflective IR principle works very well for distinguishing between white and black surfaces. A robot equipped with FC‑51 modules can follow a dark line on a light background.

must go to a Digital Input pin (e.g., D2) on your Arduino. Step 3: Measure the Input Voltage

The is one of the most popular, affordable, and essential components in the hobbyist and professional robotics community. Whether you are building an automated line-following robot, a smart parking system, or a basic collision detection mechanism, the FC-51 offers a reliable solution. The IR LED emits a 38kHz–56kHz modulated signal

Digital TTL level (Low when an obstacle is detected, High when clear)

This code reads the digital state of the sensor. If it reads LOW (meaning an obstacle is detected), it turns on the Arduino's built-in LED and prints a message to the serial monitor.

As John started the robot, everything seemed to work fine. The IR sensor detected obstacles correctly, and the robot moved smoothly around the workshop. However, after a few minutes of operation, John noticed that the FC-51 IR sensor started to heat up excessively. He measured the temperature of the sensor and found it to be around 50°C (122°F), which was much higher than the recommended operating temperature range of 0°C to 40°C (32°F to 104°F) specified in the datasheet. When reflected IR exceeds the threshold, the output goes LOW

Because FC-51 modules are mass-produced at incredibly low costs, quality control can vary. A solder bridge between pins, a faulty LM393 comparator chip, or a defective resistor can cause an internal short right out of the box. Step-by-Step Diagnostic and Fix Guide

✔️ Operating Voltage: 3.3V - 5V ✔️ Detection Range: 2cm ~ 30cm (Adjustable) ✔️ Interface: Digital Output (High/Low) ✔️ Built-in LED Indicator

Gently bend the IR LEDs so that their optical axes converge slightly. Then recalibrate with the potentiometer.