I built this project a few years ago with three normal LEDs and a 3D printed pumpkin.

I used an Arduino to control their brightness randomly so that that it looked like a flickering flame.

Each LED is connected in series with a resistor to a pin with PWM on the Arduino so that I can control the brightness.

And in the code, I change the brightness of each LED to a random value every 50 milliseconds.

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I 3D-printed my pumpkin, but you can place your LEDs in whatever you have at hand. For example a carved pumpkin or an old lantern.

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​The code is pretty straightforward

In the setup() function, I set up the LED pins as outputs. And in the loop() function, I use the analogWrite() function to set a random brightness value to each LED, with a 50-millisecond delay between each change of value.

int ledPin1 = 9;
int ledPin2 = 10;
int ledPin3 = 11;

void setup() {
  // Set LED pins as outputs
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  pinMode(ledPin3, OUTPUT);
}

void loop() {
    analogWrite(ledPin1, random(10, 255));
    delay(50);
    analogWrite(ledPin2, random(10, 255));
    delay(50);
    analogWrite(ledPin3, random(10, 255));
    delay(50);
}

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The Arduino does take up a lot of space in this project. But did you know that you can also shrink it down into a chip?

It's actually pretty simple with the ATtiny85.

(If you're an Ohmify member, you can learn how in the Shrinking Your Arduino Project course in the Ohmify library.)

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Keep On Soldering!
Oyvind @ build-electronic-circuits.com

PS: Are you into electronics and need some guidance to get to the level you want to be? Here are two ways I can help you get better at electronics:

• ​Getting Started With Electronics is the first eBook I wrote to help people get started. It’s a step-by-step guide with simple instructions to get started building electronics. Perfect for complete beginners.
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• Explore Ohmify: Whether you’re a beginner or have some experience, Ohmify helps you learn essential electronics skills and work on engaging projects to deepen your understanding.