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Blinking LED — Your First Arduino Project
E

Created by

Ed

09. March 2026

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Blinking LED — Your First Arduino Project

The classic first electronics project! Build a blinking LED circuit using an Arduino, a breadboard, a resistor, and a single LED. Perfect for absolute beginners — no soldering required.

Instructions

Gather Your Components

Collect all components from the BOM list below. You need:

  • Arduino Uno R3 — the microcontroller brain
  • 1x 5mm LED (any color)
  • 1x 220-ohm resistor (red-red-brown-gold bands)
  • 1x Breadboard — solderless prototyping board
  • 2x Jumper wires (male-to-male)
  • 1x USB-B cable — connects Arduino to your computer

No soldering is needed for this project. Everything plugs into the breadboard.

Circuit Schematic

This is the electronic schematic for the blinking LED circuit. The signal flows from Arduino Pin 13 through a 220-ohm current-limiting resistor (R1), through the LED (D1), and to ground (GND). The resistor prevents too much current from burning out the LED.

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Wire It Up

Follow these connections:

  1. Insert the LED into the breadboard. Long leg (anode +) in one row, short leg (cathode -) in the next row.
  2. Insert one leg of the 220-ohm resistor into the same row as the LED cathode (short leg). The other leg goes into a separate row.
  3. Use a jumper wire to connect the LED anode row to Arduino Pin 13.
  4. Use another jumper wire to connect the resistor's free row to any Arduino GND pin.

Tip: The resistor can go on either side of the LED — it just needs to be in series.

Upload the Blink Code

Connect the Arduino to your computer with the USB cable. Open Arduino IDE, paste this code, select your board (Tools > Board > Arduino Uno), and click Upload.
blink.inoarduino
// Blinking LED — Your First Arduino Project
// Turns an LED on for one second, then off for one second, repeatedly.

const int LED_PIN = 13;  // Pin connected to the LED

void setup() {
  pinMode(LED_PIN, OUTPUT);  // Set pin 13 as an output
}

void loop() {
  digitalWrite(LED_PIN, HIGH);  // Turn LED ON
  delay(1000);                  // Wait 1 second

  digitalWrite(LED_PIN, LOW);   // Turn LED OFF
  delay(1000);                  // Wait 1 second
}

// EXPERIMENT IDEAS:
// - Change delay(1000) to delay(100) for fast blinking
// - Change delay(1000) to delay(2000) for slow blinking
// - Try delay(50) for a strobe effect
// - Use different values for ON and OFF times:
//   delay(200) ON, delay(800) OFF = short flash
//   delay(800) ON, delay(200) OFF = long flash

PCB Layout (Reference)

This is what the circuit looks like as a printed circuit board (PCB) layout. For this beginner project you do not need a PCB — the breadboard works perfectly. But this shows you how the same circuit would look if manufactured as a real board.

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Test and Experiment

If the LED blinks: Congratulations! You just programmed hardware.

Troubleshooting:
  • LED does not light up? Check the LED orientation — flip it around. The long leg should connect toward Pin 13.
  • LED stays on but does not blink? Make sure you uploaded the code successfully (check for errors in Arduino IDE).
  • Nothing happens? Check your wiring matches the schematic in Step 2. Verify the USB cable is connected.

Next experiments:
  • Change the delay() values in the code to control blink speed
  • Try adding a second LED on Pin 12
  • Replace the LED with an RGB LED

Materials

  • Arduino Uno R3 - 1 piece
    View
  • 5mm LED (any color) - 1 piece
    View
  • 220 ohm Resistor (1/4W) - 1 piece
    View
  • Breadboard - 1 piece
    View
  • Jumper Wires (Male-to-Male) - 2 piecess
    View
  • USB-B Cable - 1 piece
    View

Tools Required

  • Computer with Arduino IDE
  • Wire Strippers
    View

📜 CC0 Public Domain

This blueprint is released under CC0. You are free to copy, modify, distribute, and use this work for any purpose, without asking permission.

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