The maximum current you can draw from the OUT pin is limited by the LM393's output stage. Do not connect the output directly to a heavy load (like a motor). Use a transistor or a microcontroller input.
| Parameter | Value / Range | | :--- | :--- | | | 3.3V – 5V DC | | Operating Current | 10 mA – 20 mA (typical 15 mA) | | Detection Range | 2 cm to 30 cm (adjustable) | | Optimal Detection Range | 10 cm – 15 cm | | Output Type | Digital (TTL: 0V or VCC) | | Output Logic | Active LOW (or HIGH – depends on board revision) | | Comparator IC | LM393 (Dual comparator, only one used) | | Infrared Emitter | 5mm IR LED (940nm wavelength) | | Receiver | Phototransistor (NPN type) | | Response Time | < 2 ms | | Adjustment | Onboard 10kΩ trimmer potentiometer | | Operating Temperature | -25°C to +85°C | | Board Dimensions | 32mm x 14mm x 8mm | | Mounting Holes | 2 x 3mm holes |
| Symbol | Parameter | Min | Typ | Max | Unit | | :--- | :--- | :--- | :--- | :--- | :--- | | VCC | Supply Voltage | 3.0 | 5.0 | 5.5 | V | | ICC | Supply Current | 5 | 15 | 25 | mA | | VOL | Output Low Voltage (sink) | 0 | 0.2 | 0.4 | V | | VOH | Output High Voltage (source) | 4.5 | 4.8 | 5.0 | V | | IOL | Output Low Current (max sink) | - | 10 | 15 | mA | | IOH | Output High Current (max source) | - | 5 | 10 | mA | | Tdet | Detection response time | - | 1.5 | 2.0 | ms | Fc 51 Ir Sensor Datasheet
| FC-51 Pin | Arduino Uno Pin | | :--- | :--- | | VCC | 5V | | GND | GND | | OUT | Digital Pin 7 |
// FC-51 IR Sensor Connection Example const int SENSOR_PIN = 2; // OUT pin connected to digital pin 2 const int LED_PIN = 13; // Onboard Arduino LED void setup() pinMode(SENSOR_PIN, INPUT); // Set sensor pin as input pinMode(LED_PIN, OUTPUT); // Set LED pin as output Serial.begin(9600); // Initialize Serial Monitor void loop() int sensorState = digitalRead(SENSOR_PIN); // The FC-51 outputs LOW (0) when an obstacle is detected if (sensorState == LOW) digitalWrite(LED_PIN, HIGH); // Turn on LED Serial.println("Obstacle Detected!"); else digitalWrite(LED_PIN, LOW); // Turn off LED Serial.println("Path Clear"); delay(100); // Small delay to avoid flooding the serial monitor Use code with caution. Common Applications The maximum current you can draw from the
If the reflected signal strength exceeds the threshold, the LM393 trips, turning on the onboard indicator LED and pulling the OUT pin LOW (0V) . When the path is clear, the OUT pin remains HIGH (VCC) via an internal pull-up resistor. Important Limitation: Surface Color Reflection
Because the sensor relies on light reflection, its effective range is highly dependent on the target object's color and texture. | Parameter | Value / Range | | :--- | :--- | | | 3
What or hardware platform you are using (e.g., ESP32, Raspberry Pi, PIC )
import RPi.GPIO as GPIO import time # Use Broadcom SOC Pin numbers GPIO.setmode(GPIO.BCM) # Define the GPIO pin connected to FC-51 OUT IR_PIN = 17 GPIO.setup(IR_PIN, GPIO.IN) print("FC-51 IR Sensor Monitoring... Press Ctrl+C to exit.") try: while True: # Read sensor state (LOW means obstacle detected) if GPIO.input(IR_PIN) == GPIO.LOW: print("Obstacle Detected!") else: print("Path Clear...") time.sleep(0.2) except KeyboardInterrupt: print("\nProgram stopped by user.") finally: GPIO.cleanup() # Reset GPIO settings Use code with caution. Troubleshooting Common Issues
The FC-51 has a standard 3-pin male header (0.1" spacing). Beware: The pin order differs between some clones; always check your board's silkscreen.