Wooden Christmas tree with colour-changing lights

Here's how we constructed a wooden Christmas tree decoration with colour-changing LED lights.

Step 1: Required parts and tools

You will need the following parts:

- 1 piece of MDF (whatever size you want your tree - ours was about 70cm x 50cm)
- Red, green and brown paint
- Hot glue sticks (lots of them)
- Slow flash colour-changing RGB 5mm LEDs
- - we used 31 for our size of tree
- - we got ours from ebay.co.uk trader "amigoofchina"
- One or two white LEDs
- - ours also obtained from ebay:amigoofchina
- One resistor for each LED, suitable for your chosen supply voltage (our LEDs came with free resistors for use with 12v)
- One 12v _regulated_ mains adapter
- - also from Ebay
- - rated at 1000 milliamps (the tree uses about 600ma, so we're not running it at maximum)
- - we chose a switched-mode adapter, because they don't get so hot, the voltage regulation is good, and it's protected against overload and short-circuit
- One inline power connector (suitable to attach to whatever connector is on your power adapter)
- One inline fuse holder (for 20mm fuse)
- One 20mm fuse (we used a 1 amp fuse, but it depends how many LEDs you're using - they consume ~20 milliamps each)
- Some flexible insulated wire
- Some solid copper wire
- - we stripped some 3-core mains wire to obtain ours
- Maybe some insulation tubing, or insulating tape
- Some thin card and masking tape

Tools required:

- Jig-saw
- Drill
- 5mm wood drill bit
- sandpaper
- pencil
- paintbrush
- soldering iron and solder
- a couple of screwdrivers
- hot glue gun

Comments

[christiank]

i will do it for this xmas

[emdarcher]

how much did this cost?

[Dr Rob]

Hi,

I don't know exactly, but roughly:

- for the bit of MDF - £1-2? You generally can't buy such a small piece of MDF on its own, but if you go to a timber merchants with a cutting service they may have an off-cut they'll sell you.
- for the colour-changing LEDs, I used 30 for the tree shown, but you can buy 50 for £8 including postage - http://cgi.ebay.co.uk/50x-RGB-5mm-White-LENs-Diffused-Slow-Colour-Change-LED_W0QQitemZ370068178291QQcmdZViewItemQQptZUK_BOI_Electrical_Components_Supplies_ET?hash=item370068178291&_trksid=p3286.c0.m14&_trkparms=72%3A1301|66%3A2|65%3A12|39%3A1|240%3A1318 (these aren't exactly the type I bought, but I've got some samples of these new diffused ones and they'd be better for the task). I have another, smaller tree with only 10 LEDs, which looks just as good.
- resistors for using the LEDs at 12v - free with the LEDs
- red, green and brown paint - ? No idea. I used some of my kids' paint that was left in the cupboard. Find some kids and look in the back of their cupboard, there's bound to be some left over.
- 12v PSU - I bought mine new from Ebay and I think they cost around £6.
- 2.1mm socket to match the plug on the PSU - £1.59 (http://www.maplin.co.uk/Module.aspx?ModuleNo=1407)
- 20mm fuse holder - 39p (http://www.maplin.co.uk/Module.aspx?ModuleNo=430)
- 20mm fuse - £1.79 (for 10!) (http://www.maplin.co.uk/Module.aspx?ModuleNo=451)
- solid core wire - already had some spare in the garage
- hot glue - 99p for a pack of cheap sticks from the local garden centre - you might not need this for the front if using the diffused LEDs, but still useful to glue everything into place at the back.

I think that's everything.

It's the sort of project where you can reuse stuff you've already got, varying the design to make use of what you find.

If you make one, please send me a picture!

[Dr Rob]

ps. If that Ebay link fails to work, use Ebay advanced search to search for keywords "RGB diffused" and Ebay seller "amigoofchina". They've given me good service but I'm not connected with them in any other way.

[Dr Rob]

pps. Oops, I forgot you need one white LED for the star. Surely you have a spare one of these lost at the back of a drawer somewhere...?

[hivoltage]

i'm thinking about making a disco dance floor style wall in my room. would these leds work as the lights? are they bright enough? also, do they all cycle through the colors at the same time, since they all start at the same time?

[Dr Rob]

Oops, forgot to answer the question about brightness: I'm not sure really. It depends what other lights you'll have in your room. If this is the only light, I guess you'd get away with cells up to about 5cm square. You can buy these LEDs in small numbers - experiment!

[Dr Rob]

Hi, The colour-changing effect of these LEDs might be a bit slow for a disco, but I believe there are some fast-flashing ones available too. The supplier I bought mine from sells the faster ones too, though I haven't tried them myself. Your main problem will be getting an evenly lit light in each cell of your wall. The lens on the tip of these LEDs focusses the light into quite a tight cone - I think it is 20 degrees. So if each cell is a square of say 5cm square, then the diagonal would be ~7cm, and to get a 20 degree cone of light to cover that the LED would have to be... (hang on while I do some trigonometry)... 9.6cm away from the semi-opaque surface of the wall. And you'd need fully-opaque matt-black dividers between the cells, to stop the colours bleeding between cells or reflecting off the sides and making the front less even. Actually, since the LEDs project a circular light, you could use hexagonal shaped cells, and "waste" less of their light. You're right - they do all follow the same sequence of colours, but since they're not crystal controlled, they all run at slightly different speeds, so they very quickly get out of sync, which is what you want really.

[hivoltage]

i do want them to get out of sync, that would probably make a cool effect. as far as the angle that the light is at, i will either add something to diffuse the light like some fibers or something, or i will just sand/grind the lens off the led. the seller on ebay also carries some 10mm leds that are about twice as bright at 15kmcd, but i was wondering if these might be bright enough by themselves.

[leahculver]

very festive! great project!