Hi,

One day, my girlfriend and I were getting ready to attend an event, but we were running late. While I was ready to leave, she was still searching through her jewelry. When I asked what was wrong, she smiled and said, "I can't find a necklace that matches my dress."

That simple moment sparked an idea in my mind: Why not make a pendant that can change its color to match any outfit?

And that's how I created the Aurora Pendant. The name "Aurora" is inspired by the beautiful Aurora Borealis, the natural light display created when charged particles from the Sun collide with gases in Earth's atmosphere. Just like the colorful lights dancing across the night sky, this pendant can glow in multiple colors, making it a perfect name for the project.

My goal was to make this pendant as simple as possible, so that even beginners and kids with basic soldering skills could build it. Instead of using a programmable microcontroller, I designed it to be non-programmable and powered by a coin cell battery, making the circuit inexpensive, reliable, and easy to assemble.

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The pendant features three individual switches, each controlling one color of the RGB LED—Red, Green, and Blue. By turning the switches on and off in different combinations, you can create 7 unique colors, allowing the pendant to match different outfits, occasions, or moods.

To complete the project, I designed two different 3D-printed enclosures. One is printed in solid white, while the other is made from semi-transparent material that diffuses the LED light for a softer glow. Since I couldn't decide which one looked better, I built both versions.

So, let's build the Aurora Pendant together and find out which design shines the brightest!

Supplies

COMPONENTS:

  1. RGB Through Hole LED (amazon.com)
  2. 3P Dip Switch (amazon.com)
  3. CR2032 SMD HOLDER (amazon.com)
  4. CR2032 cell (amazon.com)
  5. 3 X 100 Ohm SMD Resistor (amazon.com)
  6. Super Glue (amazon.com)
  7. 2 X M2 3mm heat inserts (amazon.com)
  8. 2 X M2 4mm Screws (amazon.com)
  9. Custom PCB
  10. 3D Printed Parts

TOOLS:

  1. Soldering Iron (amazon.com / amazon.in)
  2. Screwdriver (amazon.com / amazon.in)

RGB Through Hole LED

RGB through-hole LEDs are available in two different types: Common Anode and Common Cathode. To make this project as beginner-friendly and flexible as possible, I designed the PCB with selectable solder jumpers that support both types of RGB LEDs. This means you don't have to worry about buying a specific version. Simply purchase whichever RGB LED is available in your local market or online store, set the appropriate jumper on the PCB, and you're ready to go. This small feature makes the Aurora Pendant more versatile and ensures that the project can be built easily using commonly available components.

3P Dip Switch

A 3P DIP switch (3-position Dual In-line Package switch) is a simple manual switch that is mounted directly on the PCB. It contains three independent ON/OFF switches, each controlling one channel of the RGB LED. In the Aurora Pendant, each switch controls one color—Red, Green, or Blue. By turning the switches on and off in different combinations, you can create 7 different color combinations (excluding the all-off state). This allows you to easily change the pendant's color without any programming, microcontroller, or mobile app.

CR2032

The CR2032 is one of the most popular 3V lithium coin cell batteries used in compact electronic devices. It measures 20 mm in diameter and 3.2 mm in thickness, while offering a typical capacity of 220–240 mAh. For the Aurora Pendant, the CR2032 is an ideal power source because it is small, lightweight, inexpensive, and readily available. It provides enough power to drive the RGB LED while keeping the pendant compact and wearable. You can easily find CR2032 batteries in local electronics...

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