📊Arduino LED Bar Graph with Potentiometer

An Arduino beginner project that demonstrates how to create an LED bar graph using multiple LEDs controlled by a potentiometer, similar to a volume or level indicator.

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🎯 Introduction / Objective

This project demonstrates how to read an analog input using a potentiometer and display the result visually using a row of LEDs (LED bar graph).

As the potentiometer knob is rotated:

• Turning one way → more LEDs light up
• Turning the other way → LEDs turn off in sequence

⚙️ Components Used

Component	Quantity	Description
Arduino UNO	1	Microcontroller board
Breadboard	1	For prototyping
LEDs	9	Used to form the LED bar graph
Resistors (220Ω)	9	Current limiting for LEDs
Potentiometer (50kΩ)	1	Used as analog input control
Jumper Wires	As needed	Circuit connections

💡 Note: The project originally specifies a 50 kΩ potentiometer, but a 47 kΩ potentiometer was used by me.

This does not affect functionality, as both values behave almost the same in this application.

🔌 Circuit Diagram / Wiring

LED Connections

• Arduino Pins 2–10 → 220Ω resistor → LED anode (+)
• LED cathode (–) → GND

Potentiometer Connections

• Center pin → Arduino A0
• One outer pin → +5V
• Other outer pin → GND

🔄 Note: Swapping the outer pins reverses the direction of LED increase/decrease.

🧩 Breadboard View

📐 Schematic View

⚙️ How It Works

This project uses a potentiometer to control how many LEDs are turned ON, creating a visual LED bar graph.

Step-by-Step Explanation

1. The potentiometer provides an analog voltage between 0V and 5V.
2. Arduino reads this voltage as a value between 0 and 1023 using analogRead().
3. The map() function converts this value into a range of 0 to 9 (number of LEDs).
4. A for loop checks each LED:
   • If its position is less than the mapped value, the LED turns ON.
   • Otherwise, the LED stays OFF.
5. As the potentiometer knob is turned, LEDs light up or turn off in sequence, forming a bar graph effect.

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🧠 Simple Example

Potentiometer Position	LEDs ON
Low	1–2 LEDs
Medium	4–6 LEDs
High	All LEDs

🔄 Simple Logic Flow

Start -> Read Potentiometer (0–1023) -> Map value to LED count (0–9) -> Turn ON LEDs up to mapped value -> Turn OFF remaining LEDs -> Repeat

💻 Code Explanation

const int analogPin = A0;   // Pin connected to the potentiometer
const int ledCount = 9;    // Number of LEDs

int ledPins[] = {2,3,4,5,6,7,8,9,10}; // Pins connected to the LEDs

void setup() {
  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT); // Set LED pins as OUTPUT
  }
}

void loop() {
  int sensorReading = analogRead(analogPin); // Read analog input (0–1023)

  // Map the sensor value to the number of LEDs
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    if (thisLed < ledLevel) {
      digitalWrite(ledPins[thisLed], HIGH); // Turn LED ON
    } else {
      digitalWrite(ledPins[thisLed], LOW);  // Turn LED OFF
    }
  }
}

🎬 Demo / Result

▶️ Watch Demo Video

🧩 Challenges and Learning

🔹 Challenges Faced

• Fixing LED wiring when only one LED lit up
• Understanding how map() converts ranges

🔹 What I Learned

• How to convert analog values into useful output ranges
• Using arrays and loops to control multiple outputs
• How LED bar graphs are used in audio level meters

🚀 Next Steps / Enhancements

• 🔊 Replace potentiometer with a microphone to create an audio VU meter
• 📟 Add an OLED/LCD display to show numeric values
• 🌈 Use RGB LEDs for color-based level indication