How to : LED Rainbow

This is a tutorial of how to make a cheap rainbow light with LED's and tubes.

First, we search for these materials in a local DIY and electronics store, it's possible you even have them at home.

- 6mm transparent tube ( 6mm is the outer diameter, most small tubes will do the job. It only depends on the diameter of leds you'll use.)
- 8  5mm LED's, ( 2 for each colour. If you want to make a rainbow of 3,4,... or 7 colours? just multiply by two )
- Some wooden planks for the housing, or any housing that fits your needs.
- 9 Volts battery
- Resistors
- Switch
- Wiring

You'll also need following tools :

- Soldering iron for electronics
- Glue gun
- Wood Glue
- Scissors

If you have all of these, we can start with our project.
It takes about 3 to 4 hours to complete. I made it in 5 :)

Take a piece of wood or plastic and drill 4 holes, 6 mm apart from each other. (depends on the number and diameter of tubing)
Then place the tubes from the inside to the outside, until you have this kind of result.

Then use the scissors to cut the tubes off, for about 5 mm of the bottom. It is okay to leave a bit spare if you're not quite sure about the length of the tubes. Light will pass trough anyway.

After this, let's take a bath and take the tubes and led's with you. Take the tubing out of its stand and fill them up with water. Make sure there's no air or dirt inside your tubing, this will result in an ugly air bubble, shining harder than the rainbow itself. Small air bubbles could eventually have a nice effect.

While holding the tube under water, push in a led of the same color at every side so that it won't come out easily. If the led falls out, the leds you use are to small or the tubing too large.

Dry up the tubes to make sure no water gets in an electrical circuit or just to prevent corrosion.

Put the tubes back in place and you should have a result like this.

Next, is the wiring of the Leds on the battery. 9 Volts is way too much for these Led's so we'll place them in series and parallel of each other. The circuit depends on the current and voltage drop of your led's so you'll have to do the calculations by yourself. An example of my circuit :

Therefore I used Leds's which with a forward current of 20 mA  have 3.5V for blue, 2.2V for green and 1.8V voltage drops for red and yellow.

Now the only thing left to do is wire the thing up and put it in an housing.

After, the result will be like this when lightened up. The yellow and green leds were to weak to light up a bow, and aren't visible on the picture. So make sure you choose extra bright led's for an optimal result.

I made a single bow to show the result with yellow and green leds.

Pictures of the rainbow in housing will follow soon!

 Leave a comment ;)