Two fun festive projects

Feeling festive I wanted to make something novel for Christmas, so I decided on two projects. For the first I decided to make a 3D laser cut acrylic Christmas tree with LEDs, and the second a simple festive LED ornament using conductive paint for the first time.

LED tree

First I designed the two pieces of the tree in Inkscape.

This was then sent to be prototyped from MDF on the laser cutter.

I needed to make a few adjustments to the proportions, since the initial prototype was only 120mm tall and so to fit all the LEDs I wanted on it (12 in total) it would need to be quite a bit bigger. I ended up starting again with the design and more than doubled the height, and once I was happy with this I cut a second prototype.

Since I hadn't taken into account that the MDF used in prototyping is slightly thicker than the acrylic, when I tried to fit the prototype together it didn't quite fit. However this shouldn’t be a problem when cut in acrylic because it is the correct thickness.

Once fitted together it was time to do the wiring. This was the more tricky part, since I hadn't previously attempted a project that was quite as fiddly as this and had thought that wiring 12 LEDs and resistors in parallel would be easier than it was.

I made a few mistakes when connecting the first few LEDs as I accidentally connected some of the wires to the wrong side of the resistors, which meant that they were in series. I managed to rectify this mistake fairly quickly as I noticed each LED getting dimmer.

I discovered that a good way to confirm if the wiring is correct is by wiring GND to all the cathodes of the LEDs first, then when it comes to wiring the anodes you can connect the battery to see that all those which have been wired illuminate.

I had the intention of draping the wires between LEDs to give the effect of tinsel, but at the end of the wiring though it became clear that it looked a bit messy!!

I thought that adding a few ornaments to the wire tinsel might improve the look of the tree, so I designed some small stars with candy cane-like hooks to loop onto the wires. These were first prototyped in MDF and when happy with the design sent to cut in acrylic.

When completed the tree still looked slightly messy, however the small star ornaments greatly improved its appearance and made it look more like a Christmas tree. With the addition of a large star on top, secured with a hot glue gun, and some glue to the ornaments to ensure they wouldn't fall off the tree didn't look quite as well as I hoped, but for a first effort it wasn’t too bad.

Overall the tree could be greatly improved, things didn’t turn out how expected and it looked a lot messier than intended, but I’ll take this as a learning experience.

If I were to repeat this project I would spend more time planning the wiring, possibly by etching deep grooves into the acrylic for the wires to sit in, or perhaps creating small holes for the wires to be threaded through similar to sewing. By creating a design with secure placement for the wiring it would not only improve the appearance but it would make the finished project much more robust. All of these things are aspects which I should have spent more time considering in the design process, and in future I will keep in mind that there are sometimes mechanical considerations in electronics projects.

LED ornament

The Santa clause bauble was cut out of card and the electronic component is a single LED incorporated into the pom-pom on Santa's hat. The circuitry was very simple and only consisted of the battery, an LED and a resistor in series.

In place of the wires that would usually connect the components together I decided to use conductive paint from Bear Conductive, called Electric Paint. This went all around the outside of the bauble, with the battery clip wires at the bottom and the resistor at one side.

The components were “cold soldered” into place using the paint. Once this had dried all that was left to do was to connect it to a battery to see if it worked!

The Santa Christmas ornament looked really good!