Breadboard Blinker

The same blinking LED, built the way you would on a real breadboard: parts pushed into the holes, jumper wires to the Arduino.

Beginner
LED & Lighting
4 parts

Open this circuit and run it

Opens in your browser with the parts, wiring and code already in place. Press Run to watch it work, then change anything you like.

How it works

This is the LED Blinker built the way it is built in real life. A breadboard is a grid of holes, and under the plastic the five holes of each half-column are joined by a metal strip. Pin 13 goes by jumper wire to column 5. The resistor stands between column 5 and column 15, so the signal passes through it. The LED’s long leg is in column 15 and its short leg in column 21, and a second jumper takes column 21 to ground.

Nothing is wired between the parts directly; the strips do it. Anything pushed into the same half-column is connected, which is why the resistor’s second leg and the LED’s first leg meet in column 15 even though they sit in different rows. The sketch is the same as the plain blinker: setup() makes pin 13 an output, and loop() switches it on, waits half a second, switches it off, waits again, and prints each state to the Serial tab.

Parts

Arduino Uno
Breadboard
Resistor
LED

Wiring

Arduino Uno D13 → Breadboard A5
Arduino Uno GND → Breadboard A21
Resistor A → Breadboard B5
Resistor B → Breadboard B15
LED Anode (+) → Breadboard D15
LED Cathode (-) → Breadboard D21

Arduino code

// Breadboard Blinker
// Pin 13 -> jumper -> column 5 -> resistor -> column 15 -> LED -> column 21 -> jumper -> GND
void setup() {
  pinMode(13, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(13, HIGH);
  Serial.println("LED ON");
  delay(500);
  digitalWrite(13, LOW);
  Serial.println("LED OFF");
  delay(500);
}

Try changing it

Drag the LED into a different column pair, for example so its long leg is in column 14. It stops lighting, because column 14 is not joined to the resistor.
Move the LED one row down within its columns: it keeps working, because all five holes of a half-column are the same strip.
Change both delay(500) lines to delay(100) for a fast flicker.