After the previous project, I discovered how much fun it is to use RGB LEDs. I wanted an excuse to use more LEDs so I came up with an idea to make a light up heart shaped pendant.
RGB LED Heart Wearable
2017
Electronics
The electronics are quite simple for this project. I used an ATtiny85 MCU since they are very compact and are commonly used in hobby projects, meaning there is a lot of documentation online to reference. The ATtiny controls a string of 3.5mm “neopixel” RGB LEDs. There is also a on/off switch, pushbutton and a charging circuit.
The PCB was designed in Eagle and hand assembled by me.
Case
Initially I planned to 3D print the case with a resin 3D printer. Resin 3D prints can be very optically clear compared to FDM prints which tend to be more translucent than clear.
I designed the case in Fusion 360 and tried printing it in resin but ran into many issues. THe thin walls of the case broke during printing due to the suction forces when the build plate lifts after each layer. To reduce this issue the part could be printed at an angle using support material, however after removing the support material the surface was left scarred and not didn’t look nice.
I decided to print the case with an FDM printer instead which was much easier, although I had to print several cases to get the tolerance perfect. The translucent appearance of the FDM prints are somewhat beneficial since it helps to diffuse the light from the LEDs.
The Wanhao Duplicator 7 was one of the first affordable resin 3D printers on the market.
These are the test cases I printed trying to get the tolerance right for the case halves to fit together nicely.
Conclusion
This is one of my favourite projects. The idea and the hardware is very simple, but there is something very satisfying about watching the RGB LEDs light up. It was also a lot of fun programming the light animation. I plan to do more wearable projects in the future.