The USB powered LED CD lamp

The USB powered LED CD lamp is a very useful gadget. It's powered by the USB port, so you don't need any external power supply. The stiff mounting wire, I used acts as a gooseneck and lets you bend the light source in different angles and directions.

Step 1: Get the parts

Here is a list of the parts you'll need to make this lamp.

4 CDs or DVDs (and if you're rich, you can even use Blu-ray discs or HD DVDs)

7 5mm White or warmwhite LEDs, I used warmwhite, because that I'm tired of the cold light, you get from the ordinary white LEDs. (I've posted some pictures, so that you can see the difference between the white and the warmwhite LEDs)

7 Resistors for the LEDs. I calculated, that my resistors should be 68 ohms. you can find a very good resistor calculator here.

Some electrical mounting wire. Should be the stiff type (the one with only one thick cupper conductor)

5 AA batteries preferably Duracell, cause they're the heaviest (the batteries are just there to act as a counterweight. Without them, the lamp would just tip over and fall).

A switch (optional)

Some ordinary hookup wire.

A USB male A connector with cord (I got mine from a broken webcam)

Some wire without insulation.
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cvolckmar3 years ago
I have a challenge here. I have a power source that is 53v DC and I want to use 7 Super bright LEDs. I'm new to electricity and I think that it will blow the LEDs since they run on a few volts each. What size resistors do I need use? And where do I install them? I need to use the 53v source. Please show calculations. THANK YOU in advance =]
3 years ago
add the voltages of the LEDs
subtract from the 53v source
divide with the LED current , most LEDs have 20mA so it is .02 A

so
R=(V1-V2)/.02A
5 months ago

Best way in your case is to put them in series (i.e. you chain the LEDs and then you add a resistor). But I'd discourage you using that power supply for this application.

High brigthness LED could draw significantly more than 20mA...

Let's suppose you have 7 LED rated for 1.5V @100mA

You would need a resistor sized like this:

R = (53V - 7*1.5V)/100mA = 425 ohm

So your LED will use this power

P = V * I =7*1.5V * 100mA = 1,05 W

P = (53 - 7*1,5) * 100mA = 4,25W ...

That means that you would not blow your LEDs but you'll probably blow your resistor, or if you have a resistor rated at least 5W, you'll end up with a heater more then a lamp, as the resistor will use 4 times more power than the LEDs...

For this kind of application you should use a DC/DC converter, but it's definitely no subject for a novice...

I really like this project. Really creative and elegant. I've made a similar project on my blog and featured you.

rimpelido2 years ago
Does this double the consumption of the energy from the laptop or desktop?
sherryk2 years ago
leds r always connected in parallel.with a 1k resistor each,try in series,they wont light.am good in this.
nemanja923 years ago
hello can someone tel me why i can powered Led lights by USB???
taurusguy885 years ago
well i made my usb lamp,
but i connected all the led in series
but the pro is i get a notice on my pc
power serge on usb ...
whts to do with tht ??
3 years ago
you short connected something
nodoubtman4 years ago
Hello! : How do you get 68 Ohms resistor ??

So : 7 LEDs 20 mA each, 3.5 V each to run, 5 V usb max.

R = (5 - 3.5) / (0.02 * 7) = 10.71 Ohms near value = 12 Ohms. Which is far away from 68 Ohms resistor.

Can you give me your trick? :)

Have a great day! :)
DrChill7 years ago
Just a suggestion. You may need just one resistor. Just wire it so its between each LED and power. I'm guessing a 1/2 or 1 watt resistor should do the trick... It will save a little solder and 1/2 dozen parts ... Nice job. : )
7 years ago
It is a bad idea to wire LEDs in parallel as you are sugesting.

I'll quote from The Electronics Club:

Connecting several LEDs in parallel with just one resistor shared between them is generally not a good idea.
If the LEDs require slightly different voltages only the lowest voltage LED will light and it may be destroyed by the larger current flowing through it. Although identical LEDs can be successfully connected in parallel with one resistor this rarely offers any useful benefit because resistors are very cheap and the current used is the same as connecting the LEDs individually.

7 years ago
Yeah, I've heard that to, and that's why I didn't do it.
4 years ago
Are the led in parallel or series ??

thank you!
CYa!
7 years ago
"If the LEDs require slightly different voltages -only- the lowest voltage LED will light " No. And how much is 'slightly' anyway ? Is 2v 'slightly' different than 3v ? As long as the resistance is appropriate for each LED and the resistor can handle the load, there's no problem. Since this DIY uses the -same- LEDs, they need the -same- current, so there's no problem. And, as the last line of the quote says,"...and the current used is the same as connecting the LEDs individually." Thats my point. Its the same. It's the same current unless the LEDs -are- different, and if they ARE different then use different resistors, not 7 of the same ... Try it yourself. Its easy to test and see who is right here... I like elegant solutions, not wasting parts, and not scaring people away from simpler solutions without understanding why. If you like wasting parts, I have lots of projects for you to try ... ; )
Artificial Intelligence (author)  DrChill7 years ago
OK, then do it your way. And what projects could I try to waste parts.
7 years ago
You should post up some instructables of your own. A.I. and I both have posted instructables where we wired circuits for LEDs. Not that simple LED circuits are that challenging but you might be able to demonstrate what conditions are required to use a single resistor safely.
7 years ago
Thanks for the suggestion. AI's project is a good candidate for using one resistor for all ( not each ) LED. As long as each LED has the same specs, and the resistor is properly sized, it would work. I started playing around with using the PC power supply as a source of power for projects including an LED Lamp.... I'll keep you posted. Regards.
7 years ago
I'm not scaring people off, I'm stating the generally accepted rule of circuit building.
7 years ago
Sorry. The Electronics club doesn't have it quite right.

Its NOT a generally accepted rule. Its a waste of parts, and there's no logical justification for it.

I will say that as a design rule, simpler is better.

Here's a link that discusses LED wiring more fully and accurately than the Electronics Club.

From circuitry 101:
http://www.theledlight.com/ledcircuits.html
Vanix5 years ago
What resistor did you use, not sure if i need any specific type of thing or what... I am making this project for my computers class. Thanks for the help.
Artificial Intelligence (author)  Vanix5 years ago
As I said, it really depends on the LED specs. When you buy LEDs, you've probably got the specs with them. Usually, 5mm white and warmwhite LEDs has a voltage drop of 3.6V and a drive current of 20mA. You may use a series resistor calculator to find the appropriate resistor. I always use ledcalc.com.
4 years ago
If you put those on parallel if : voltage = 5v, Current across led = 3.6, 20 mA each led to run, 7 leds total, = 10 Ohms resistor? right?..

why did you put a resistor of 68 Ohms?

Thank You!
Have a great day! :)
jbernal14 years ago
Thanks for your nice work. Actually your work inspired me to made my own usb lamp, I used your "on-CD circuit" design, but the difference is the base, I did it with Legos!! xDDD Can I share some pictures later?

zsingh4 years ago
Great effort to reduce e-waste. GREAT Keep it up
yogesh_nik4 years ago
Amazing use of scrap good to recycle my all scrap CDs.
jtc105124 years ago
I wonder if you solder a USB port to it, it will act as a USB extender. Since the lamp itself would be taking up a usb port, you could regain the amount of free USB ports on your computer. For that, you would not cut off the data wires.
Gideon Ackon5 years ago
Why did you add the batteries? Is the batteries going to be charged? Why not the USB connected strait to the switch and the LEDs? Please send me the answer to piechart88@yahoo.com
4 years ago
The Batteries are a counterweight not for power,
just use something more efficient than batteries though.
drf0095 years ago
what is resistor volt?? 250ohm???
nacho.cheese5 years ago
excellent work!!!...
I did one, and it work nice...
georgettemarston5 years ago
Hi my son is doing this for a school project and we cant open the step by step instructions without being a member we have all the parts , could someone paste the instuctions and email to me would be greatly appreciated thanks a bunch,

sweetmaria_33@yahoo.com
Vanix5 years ago
I am looking at these right now

2.2K ohm, 1/4-watt, 5% tolerance carbon-film resistors sold in packets of 5.

• 2.2K ohm
• 1/4-watt
• 5% tolerance
• Package of 5

markymonkeymark5 years ago
@sir Jan 12, 2010. 4:25 AMArtificial Intelligence
- wow nice...its really work... i already made one for my new modding project...soon ^_^ ...
see my worklogs here...

http://s358.photobucket.com/albums/oo30/markymonkeymark/Pc%20Mods/Wirings%20and%20Electronics/?start=20

thanks a lot...
pr.sreehari5 years ago
wooow its very nice.
but  5v in usb port is enough to drive those 6 leds??
thnx
5 years ago
5 Volts is enough, because the LEDs are driven in parallel instead of series.
5 years ago
yes u r right
i did it
markymonkeymark5 years ago
Hi sir Artificial Intelligenc, nice work... im just wondering, what happen to those green and white wires?where did you connect those?white wire connected to red wire(5v+) , and the other one which is the black (grnd), did you connect the green one?

im just a noob and willing to learn...