Glowing Led Christmas Tree Topper

Hi! This is my very first instructable. Several times I started writing something, but never actually posted anything. However, this time I decided to go through, and complete this instructable.

This guide is intended to build and develop a glowing high intensity led Christmas tree star. It is made using pine wood, ws2812b led strips and arduino.

please make any suggestion, advice, comments and post your photos! Thank you!

Tools and Materials

Here is the list of the required material. None of them is strictly needed and could also be replaced by anything you prefer, as long as it is suitable for the needs.

1x Pine wood (plywood or any other wood will be okay) Approx 30x30x0.6cm (12x12x0.25 inches).
1x 67cm long (40 leds) ws2812b led strip with 60leds/m. You could also use a different number of leds, as long it is a multiple of 10.
1x small-sized ATMega328-based or ATTiny45 board (Pro mini 3.3/5v or Adafluit Gemma are suggested)
Medium grain sand paper
Acrylic glue
1x 3.3/5v power supply or 3.7v LIPO battery or any other suitable power source
Thin electric wire (black suggested)
Scissors
Pen (better if not black) or pencil
Ruler
Carbon paper
Jigsaw (suggested) or hand saw
Slodering iron

Draw the Star

The first step is the star creation. It is important to keep in mind that leds will be attached onto it, so proper measures have to be considered. For the described design (40 leds), you can use the stencil attached. Note that, in order to fit an A4 sheet, some ends were clipped. So, print the stencil, pick your wood sheet and carbon paper sheet. Put the latter on the wood (black side down please! ;-D) and stack the stencil on to it. Now, using the ruler and the pencil/pen, trace the edges of the stencil, so that it will copied to the underlying wood. Take care not to move the stencil while tracing. Once finished, resist the temptation to remove the stencil and double check all the edges (if you use a coloured pen this task is easier).

Now, remove the stencil and you should have the perfect reproduction of the star shape on your wood. You are ready for the next step.

Downloads

stencil.pdf

Cut the Star

Once the star is traced on the wood you can start cutting it using the jigsaw. I cut only the outer edges, but if you prefer you could also cut an hole inside the star by cutting the inner edges too. This step is quite easy and should not be problematic.

Once finished cutting, I suggest to sand the edges to make them smoother. The pine wood I used was already planed so there was no need to sand the surface too.

Prepare the Leds

Now you have your star, but till now it could simply be used as a decorative garland (hey, it is still a cool idea!). It is time to prepare and attach the leds.

Pick your 40 leds strip and using the scissors cut it into pieces containing 4 leds. You should end up with ten pieces (see figure)

I preferred to remove the waterproof tube, but this part is up to you. If you decide to cut it, make the cuts on the side, avoiding to damage the strips.

Important: before glueing the strips, make sure that the strips are oriented correctly. The Do contact of a strip should be followed by the Di contact of the following strip.

Glue the strip using the acrylic glue. Use some drops on the back of the strips and place them on the star using the pattern show in figure. Try to align the strips so that the pixels are even spaced. If you make mistakes slowly remove the wrongly glued strip and apply other glue before performing corrections.

Move to the next step.

Wire the Leds

Now, strips should be wired. Cut short pieces of wire, but not too short, 3-4 cm should be a good size. Using your soldering iron, connect Do contacts with Di contacts, V with V and GND with GND. You will test the wiring in the next step. By now just give a visual inspection aimed to check that there are neither interruptions nor overlaps between solderings.

Warning: Do not close the chain! The last strip has not to be connected to anything, while solder longer wires on the first strip leaving the other ends unsoldered, they will be connected to the microcontroller board.

Wire the Microcontroller

Connect your power and ground pin to your power source.

Connect your Vcc and GND pin to the V and GND contacts of the first led strip

Connect pin 6 (if you feel confident with your coding, you can also use another pin, most are valid) to the Di contact of the first led strip

If you are using Arduino Pro Mini wire the programmer pins to your serial programmer. Otherwise just plug your USB cable.

Program Your Microcontroller

In order to program your microcontroller board, you need an Arduino IDE equipped with the Adafruit Neopixel library, that can be downloaded from Adafruit site.

Once you are set up, upload the strandtest example sketch from:

File→Examples→Libraries→Adafruit_NeoPixel→strandtest

edit line 15, change 60 to 40, as we are using 40 leds. Leave the rest of the sketch unaltered.

Note 1: if you use an Adafruit Flora or Gemma Board, you will need to setup the board in the Arduino IDE, please follow these instructions.

Note 2: If in the previous step you used a different pin for led strip output, reflect such change in your code.

Test Connections

Now it is time to check your connections and wiring. Plug power on, and, if everything went smooth, all the leds will glow according to the uploaded sketch. You are done!

If some or all of the leds are not turning on, you should check your wiring, starting from the strip close to the board. Once you make it working, probably the following will turn on too, otherwise iterate again checking the first strip not turning on. Repeat until all the leds work correctly.

Final Touches

Before installing your star to your tree, you need to secure the board on the back of the star. You can use screws or tape. You also need a way to hold the star to the three top. For this purpose I used two screw eyes of proper size (see figure) which resulted a stable and nice solution.

Attach it to your three top and turn lights on, you are done!

Congratulations!

Thank you for reading this instructable, if you make this project, please make any suggestion, advice, comments and post your photos! Thank you!