Introduction: USB Laptop Light

Quick, easy and cheap way to make a USB laptop LED light. I made this one in about 20 minutes with spare parts. Great for presentation or just night time surfing.

Comments

author
gamer (author)2008-02-27

why are you putting the green and red together??? what about the white and black? why didnt you put a resistor on your l.e.d. (why do you say it is 5 volt 30 mA)? nice project, except for a few... lot of questions i asked myself while you were building it... -gamer ps. please answer the many questions, because i dont understand half of the stuff about this video, and i know a lot about L.E.D.s and USB... thanks

author
irishjim68 (author)gamer2014-08-28

All diodes (including LEDs) are CURRENT DEPENDENT devices. This means
that the current flowing through the device must be limited to the
specifications of the device (Too much current, the device will fail.
Too little current, the device will not conduct properly). The 30ma
rating on the package is the safe working current of the particular LED
chosen for this project, therefore, one needs to choose a resistor
soldered to the negative leg of the circuit to LIMIT the current flowing
through the LED in order to not have it burn out. As [mellink] explains
below, Ohm's law is used to calculate the value of resistor to limit
the current through the circuit to the proper value with the supplied
voltage.

author
mellink (author)gamer2009-06-19

can i help.
The LED when supplied with 5V and 30mA (3x10-3A) needs a resitor to stop the current burning out the LED.
Use V=IR to calculate the resitor value.
in this case:
V/I=R
5/(30*10-3) = 166.6 Ohms
So just go for a resistor near that and your safe.

author
SRRPC (author)mellink2010-03-04

hey i was wondering if i could damage anything on my laptop if i touched the positive and negative together.?prolonged or momentary i jus want to know before i damage anything.
thanks

author
murray182 (author)gamer2009-03-16

+1

author
branedge (author)gamer2008-02-27

someone will have to explain the resistor to me....i dont quiet know why to use it. i can add that the laptop light 2.0 version. gamer - the ledinfo 5 volt 30 mA came off the package...was trying to tell folks what i used. from my research(not a lot) on usb cable the red and black are for the power the white and green are for data...when i used these it windows tried to discover my usb device and i only wanted power. plus these are the color combinations that worked, hope this helps will answer more if u want

author
gamer (author)branedge2008-02-28

im guess gonna have to make an instructable about the usage of a resistor, so everyone understands... when i try to get power from the usb port, i use the black as the gnd, and the red as the vcc (positive)... the data shouldnt be used, this is just giving the laptop a 1 on both data, and it wonders what that is supposed to mean... anyways... if it worked.

author
eydryan (author)gamer2008-10-10

he meant the white and green wires of his led :)

he didn't touch the white and green data wires.

author
Noodle93 (author)gamer2008-02-29

He said that the LED was safe at 5v without it being destroyed. USB ports power 5v.

http://upload.wikimedia.org/wikipedia/commons/thumb/6/67/USB.svg/700px-USB.svg.png

author
Yerboogieman (author)gamer2008-03-13

i had a 5volt 30mA LED they sell em at radio shack, they only need about a 1/4 watt 100ohm resister and they work fine

author
sinner_93 (author)2011-05-23

My LED just flashed thrice, and then gives out a very dim light. Why is this happening? BTW I used the USB plug from an old mouse, is it because of that?

author
pennachi1 (author)2010-02-28

I just did this and it works great. Took five minutes and now I am writing in the dark.

author
gnuoy (author)2009-10-26

it looks very iteresting, but could you please post a regular non-video version of the guide? metacafe players is terrible and won't let me see it

author
HiImLizzay (author)2009-05-12

Great video! I made my own, and added my girly touch to it, I thought it would be cool if it looked like a flower so I made "petals" made of acrylic paint, puffy paint, and aluminum foil for the reflective purpose! I also spray painted the "stem" green, and voila a really fun project! I also ended up using some tubing for fermenting beer to stabilize the wire so it didn't droop down from the usb port (that was my own mistake because i didn't extend the wire far enough to the base) but it worked fabulously! Thanks for the video it was great! PS- It defiantly didn't need a resistor.

IMG_1527.JPGIMG_1528.JPG
author
carrierpilot1357 (author)2008-10-18

try diffusing the led and it should be even better!

author

Yeah good idea, I would definitely do that if I was going to make this.

author
spartansi2 (author)2008-10-13

i made one and it works great!

author
shooby (author)2008-09-14

They sell USB LED keyboard lights at my local dollar store. For 1$ US.

author
npsark (author)2008-04-01

i suggest you sand the led to diffuse it a bit. very nice though

author
iMoody89 (author)2008-03-18

10x very much for this video i used it to fix my laptop cooler thanks a lot again nice job

author
branedge (author)iMoody892008-03-18

Glad to hear it. glad you liked

author
Brennn10 (author)2008-02-27

This is good for the dark! Nice and easy, I like!

author
GorillazMiko (author)2008-02-27

Pretty cool! You most likely WOULD want to add in a resistor. Very nice job anyways!

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