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Basics project 108a Proximity sensor FC-51

Basics: Project 108a

Project name:  Proximity sensor FC-51

Tags: Arduino, Arduino Nano, proximity sensor, distance sensor, MH-B, KC-51, infra red distance sensor, IR Infrared 2 – 30cm, Obstacle Detection Sensor Module FC-51, IR Sensor, obstacle avoidance sensor

Attachments: sketch

In this project, you needed these parts (Dear visitors. You can support our project buy clicking on the links of parts and buying them or donate us to keep this website alive. Thank you):

1. Proximity sensor FC-51 1pc


2. Jumper cables  F-F


3. Arduino Nano and Mini-B USB cable 1 pc



We will learn how to use the proximity sensor FC-51 with Arduino Nano.

Understanding the Arduino Nano

You can read more about it here.

Understanding the proximity sensor FC-51

Infrared Obstacle Avoidance Proximity Sensors Module has builtin IR transmitter and IR receiver that sends out IR energy and looks for reflected IR energy to detect presence of any obstacle in front of the sensor module. The module has on board potentiometer that lets user adjust detection range. The sensor has very good and stable response even in ambient light or in complete darkness.

The sensor module can be interfaced with Arduino, Raspberry Pi or any microcontroller having IO voltage level of 3.3V to 5V.


  • Obstacle avoidance in robots
  • Production counting on assembly lines
  • Presence detection
  • Security systems


  • LM393 Comparator based detection circuit is very stable and accurate
  • On board potentiometer sets obstacle detection range
  • On board Power LED indicator
  • On board Obstacle Detection LED indicator
  • 3.0 mm mounting hole for easy mounting the sensor.
  • Male header for easy connection
  • Good Accuracy: By use of Infra-red LED transmitter the module performs well in Ambient light

Technical Specifications:

  • Model Number: FC-51
  • Detection angle: 35 °
  • Operating Voltage: 3.0V – 6.0V
  • Detection range: 2cm – 30cm (Adjustable using potentiometer)
  • Pcb size : 3.1 cm (L) x 1.4 cm (W)
  • Overall Dimension: 4.5cm (L) x 1.4 cm (W), 0.7cm (H)
  • Active output level: Outputs Low logic level when obstacle is detected
  • In-active output level: Outputs High logic level when obstacle is not detected
  • Current Consumption:
    • at 3.3V : ~23 mA
    • at 5.0V: ~43 mA

LM393 Comparator IC Datasheet.

Signals and connections of the FC-51 Proximity sensor


VCC – 3.3 to 5 VDC Supply Input pin
GND – Ground Input pin
Signal out – Digital output pin. LOW when obstacle is in range
Power LED – Illuminates when power is applied
Signal LED – Illuminates when obstacle is detected
Variable resistor – Adjust detection distance. CCW decreases distance.
CW increases distance.

Signals and connections of the Arduino Nano

You can read more about it here.



Step by Step instruction

  1. Do wiring.
  2. Open Arduino IDE.
  3. Plug your Adruino Nano board into your PC and select the correct board and com port
  4. Verify and upload sketch to your Adruino Nano.
  5. Open up Arduino IDE Serial monitor and set your baud to 9600 baud and select Both NL&CR.
  6. Move your hand towards the IR LEDs. As you near them, the output LED on your Arduino Nano will illuminate. Open your serial monitor and vary the distance of your hand while viewing the serial monitor. The output should show “clear” to “OBSTACLE!!, OBSTACLE!!”.


We have learnt how to use the proximity sensor FC-51 with Arduino Nano.

Thank you for reading and supporting us.


  • None

Project resources:

  • See attachments on the beginning of this project description

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