This Instructable will show how to build a very bright usb powered led light. This can come in very handy while working on your computer or lighting up your keyboard in the dark. Another possibility of this light could even be for a mood light, because it can be placed behind a monitor and shine onto the wall or ceiling. This is my first Instructable so I hope you enjoy!
Step 1: Materials
The first thing you have to do is gather your materials. ALL of the electrical parts I used to build this project were scrapped off old electronics I had laying around, and the tools needed are pretty common.
Things used for this project:
-Solder (duh :P)
-Hot glue gun
-Screw driver (for making holes)
-12 white LED's
-Small box (or anything that can hold the components)
Step 2: Getting Started
After gathering all of the materials you can now begin the modification of the box. First thing you need to do is to mark a spot where you want to put the usb cable. Now using a screw driver (or nail, or anything pointy) make a hole where the mark was.
Step 3: The beginning of a brighter future
You now have a hole in your box and you are sitting there wondering what to do next. Well...now you need to get a usb cable. The usb cable doesn't have to be anything special just as long as you can strip the wire for it to fit in the hole you made earlier, but of course the usb cable also has to be working so that you can plug it in when you're all finished. For this project you will need to cut off the green and white cables and keep the red and black, the reason being is because the black and red cables are the power cables. After the cable has been spliced you now need to put it in the box, and when after you do I recommend tying a knot so that the cable wont be pulled out or moved out of place.
Step 4: What would we do without one of these?
Switches are a part of everyday life, and with the use of a switch it is now possible to control when it's on or off...instead of constantly plugging and unplugging your usb cable. With that in mind, you will need to purchase a small switch like the one below. That switch was purchased many years ago but can be bought for around a quarter a piece. Then you will need to mark another hole, but this time it needs to be much bigger because you're going to be putting the switch in. After marking the hole you should then use your knife to cut out the hole and then fit the switch nice and snug in its place.
Step 5: Connection to the switch
I know that you've just cut that nice new hole and now your switch is in place, so what you need to do next is to connect your usb cable to the switch. Out of the 2 wires that are left in the usb cable, you will only be connecting the red wire to the switch. Solder the red wire directly to the switch on one pin, and then on the next pin you will need to solder another extra piece of wire.
After you have the two sections of red wire attached to both pins you will now need to add a resistor. For this project I used a 47 ohm resistor (which was more than enough...but better safe than sorry.) to figure out what size resistor you will be needing you can go to [http://metku.net/index.html?sect=view&n=1&path=mods/ledcalc/index_eng] Now attach the last section of red wire to the other end of the resistor and solder in place.
47 ohms was assuming that each LED takes 3.6 volts and 20ma to run.
Edit!: ACTUAL RESISTOR SIZE SHOULD BE AROUND 70 OHMS and for best results you should solder 1 resistor to the leg of each LED.
Step 6: LED time!
Actually we're close...but it's not quite LED time. It is however time to mark your holes on the lid of the box for where you want your LEDs. In my design below I have it set up as 2 rows of 5 and 1 row of 2 becoming a total of 12 LEDs. But anything will do and you are not limited to this design by any means.
For making the holes to fit the LEDs, I found that it was quickest to burn each hole out with your soldering iron, and from there expanding the hole with a screwdriver or anything large enough.
Now that your holes are made, you can now place the LEDs in the holes. Make sure that you put the LEDs in from the bottom, because the ring on the LED will help secure them inside. Something very important to note is that all of the LEDs should be facing the same way. In other words, each Anode should be on the right, and each Cathode should be on the left. After they are pushed into place and each anode and cathode line up correctly you should now use a small amount of hot glue to keep JUST the plastic of the LED in place, you DON'T want to get much hot glue on the legs of the LED because the LEDs soldered still.
Step 7: Now it's actually LED time!
Now it's time to wire the LEDs, which is quite a long process since I didn't have any sort of circuit board to work with (which would've been much safer, and cleaner). In case I didn't mention it before...the LED setup is running in parallel, due mostly to the fact that the voltage of USB power is only 5v, so with the parallel setup it was possible to power each of the LEDs at a maximum voltage. The pictures pretty much explain how to wire the LEDs. It's important to leave some extra wire hanging off like it's shown in the picture so that it can later be attached to the base of the box.
[The wires between each LED are going to be bare, make sure to add some hot glue to the overlapping wires to keep them separated, otherwise the circuit will short out, and the LEDs will either flicker or not light at all]
It is also important to note, that if the polarity is wrong, the LEDs will not light at all.
Step 8: You're almost there!
The LEDs are wire to the lid, and the switch is wired to the base, what next? you attach them! All that's left of this project is completing the circuit by connecting the anode to the red wire, and the cathode to the black wire (directly from usb cable) The black wire however needs to be extended in order to reach the other wire.
After everything is wired up, now all you have (should) do is cover the bare wires in electrical tape to prevent any short circuits, and you also might want to glue/screw in the switch that was put in at the beginning to make it more permanent. see pictures below...
Step 9: Let there be light!
All that's left of this is putting the two halves back together for the final time, and putting a small amount of glue around the edges to make the box stay together.
And the moment we've been waiting for is here...plug in the usb cable and flip on your switch. If all went well, you should have a nice and bright USB-LED light!
Step 10: Finished
This project was actually my first project that had to do with LEDs in a circuit, and was a learning experience for me (not that it was very hard at all) and now I have a great light to work on my computer with or do whatever.
I hope somebody tries this project, and I would love feedback since this is my first Instructable ;)