Incense adds a nice mood to a room, as does mood lighting. This instructable shows you how to modify an incense burner to subtely glow via hidden leds. The combination of light, smoke and nice smells makes for a really cool chill-out object that looks quite magical.

This project is really easy to build and is very cheap, making it a great beginners electronics project. Hence, I've written this instructable with beginners in mind. Also, the modification is done in such a way that you won't do any damange to your incense box and is easy to remove whenever you want.

I gave this incense burner to a friend of mine when he graduated. Hope you're as happy with yours as he was with his :-)

Step 1: Stuff You Need

For this project you will need:

1. An incense burning box
The type with a closing lid and holes for the smoke. You can usually pick these up in new age or fair-trade shops. This one cost around £6.00 and takes either incense sticks or cones.

2. Some square dowel
You can get this at all good hardware shops. The stuff I use in this project has a profile of around 8mm square. 1 meter cost about £1.50

3. Leds.
I used 3 green ones but this is where you get to be creative. No reason why you can't have different colours. I chose some with a wide viewing angle to get a nice distributed light.

4. A Swtich
I took mine out of a broken torch (flashlight). You want something that you can mount inside the box when the lid is closed. It also needs to lock in position (like a light switch).

5. Battery holders + Batteries
2 single AA holders provide enough power while not taking up too much space.

6. A bit of wire
To connect it all together (two different colours)

7. Heat shrink (optional, you could use tape)
To prevent short circuits

9. A bit of Tape (duct, electrical or masking tape all good)

10. An elastic band

Tools
You will require this modest selection:

1. Soldering Iron + solder
2. Super Glue
3. Pencil
4. Junior hacksaw
5. Strong safety pin / Tack
6. Helping hands / crocodile clips (optional but a great tool to have anyway)
7. Small piece of sandpaper (a file will do)

Step 2: Cut and Fit the Dowel

The square dowel is going to act as the holder for your leds and needs to fit inside the incense box.

Measure the inside of the box and add 1mm. Mark this length with your pencil and cut using your hacksaw.

The extra 1mm means that the dowel is a tight fit in the incense box so won't rattle around. It also means that you can angle the leds as you see fit. If it is too big to fit then sand / file the end of the dowel. If it still rattles round then just put some tape on the end, you'll see that I do this later on in the instructable after sanding my dowel too much.

Step 3: Mark the Led Postions

Push the dowel into the box and mark the positions for your leds with an X using your pencil.

I put one in the middle and the others half way between the middle and the end. So if you were to divide the dowel into quarters the leds would sit on the dividing lines (see the picture in step 1 if you are unsure).

Step 4: Make Holes for Leds

Now you are going to make some holes for your led legs to fit into. I use small 3mm diameter leds so my holes are 3mm apart. If you are using different size leds you should change your hole width to match.

With a strong pin, make some indents either side of the X. Then push these holes right the way through with a tack for a pin board.

NOTE: I put the holes to the left and right of the center of my middle X but above and below the center of the outer X's. This means that I can angle the middle led up and down but bend the other two leds to point away from the middle. You'll see this in the next step.

Step 5: Insert Led Into Dowel

Push the leds of the leds through the holes in the dowel.

Leave a few mm of wire at the top so that you can bend the leds later on. You can see in the second picture that two of my leds are orientated to bend outwards while the middle one is orientated to bend up and down.

Step 6: Solder the Leds Together

You now need to solder the leds together in a parrallel arrangment. So the long legs all connect together and the short legs all connect together. I like to put a bit of heat shrink on the long legs to prevent a short circuit, if you don't have any heatshrink you could use a bit of tape. Use a different colour for the positive and negative legs.

Bend the legs of the leds against dowel before you start this. I used a crocodile clip / helping hands to hold the wires against the dowel while soldering. This means I can easily make the wire just the right length so it doesn't stick out from the dowel. If you don't have a clip you could just tape the wire to the dowel.

Solder two longer wires to the leds, this is how you will connect your power. These wires need to be long enough to bend around inside your incense box and connect to the battery pack (look at the picture in step 1 if unsure. You can either solder them both to the same led (as in the pictures) or solder your positive to an led on one end of the dowel and your negative to another led on the other end of the dowel, just make sure you solder to the correct legs!

If you have a spare power supply you may want to test your leds now, if not don't worry, you can test it later with the power pack we're going to build in the next step.

Step 7: Make the Battery Pack

It takes 2 1.5V AA batteries to light up 3 leds directly. I used AA as they'll last for ages.

Take two single AA battery holders and superglue the negative (spring) end of one to the positive (flat) end of the other. Hold them together with an elastic band.

Now, this bit is a bit tricky if you are new to soldering. After the glue has dried (or while it's drying if you are impatient like me) bend the legs of the glued ends of the packs together so they touch one another. Now solder them really quickly so that you don't melt the plastic.

When that is all done solder the positive wire from your leds to the positive terminal of the battery pack.

Step 8: Solder the Switch

Now solder one side of your switch to the negative end of your battery pack with a piece of wire. Solder the other side of your switch to the negative wires coming from your leds.

This is a funny switch that I pulled out of a broken torch. It's nice because it's locking push to make. I wish I knew where I could buy more of these (please message me if you know).

Don't worry if you can't find a similar switch, any small switch will do the job.

Step 9: Test the Circuit

Put in some batteries into the pack and push / flick the switch.

Hopefully it works :-)

If not then the chances are that you have one of the leds in back to front or might of connected the postive end of your batteries to the negative end of the leds. This is a really simple circuit so there are only a few things that can go wrong.

You'll notice in the picture that I've introduced a bit of tape on my dowel, this keeps the wiring tidy and means I can push the dowel into the box without scratching the varnish. It's also because I sanded my dowel too much in step 2 :-\

Step 10: Put It in the Box

Put everything in the box. I put a bit of tape around the batteries as they had a tendancy to pop out (cheap holders).

Try to leave the middle of the box clear to prevent the incense dropping ash onto your circuit.

Don't forget to angle the two outmost leds away from the center to distribute the light nicely. Also angle the dowel so that the leds all point towards the center of the lid.

Make sure the lid can close nicely.