How to light a LED or regular light with USB!!

This Instructable is going to teach you how to light a light bulb through a USB!!

SORRY: I currently have no camera so I can not load up any pictures!

BUT: I do have a scanner so I will do the best I can.

I guess you could use this when its dark and you don't have a light source or you want to save money. :P

Step 1 MATERIAL

You will need:

1) USB Cable. (Male Type A)
2)LED, regular light (what I used)
3) Electric Tape (I didn't have any so I used regular clear tape and burned it to mold it)
4)A Computer (duh... to power the light)
5)Scissors
6)Wire Strippers

Comments

[or_ford98]

cool substitute for soldering irons, i have to try that !!! :))))

[or_ford98]

nice idea of scanning the objects instead of taking pics.... ill try that sometime :)

[graphak]

I tried something similar. Using an LED hooked up to the end of a USB. The LED light worked, but after a while started smoking and would have eventually burnt out, or worse.

I also tried it with an on/off switch and got an error from Mac OS X that it was disabling the USB port because it drew too much power...had to restart to get it back to normal. Thank god for safeguards eh? Needless to say thats the last time I will experiment with my pricey Mac USB ports until I know EXACTLY what I am doing.

A resistor was definitely needed in my case. Here is a site with instructions for various LED configurations and a resistance calculator that I found very helpful for an electronics noob. http://www.llamma.com/xbox360/mods/How%20to%20use%20an%20LED.htm

The point is that impatience and experimentation without proper knowledge almost always leads to disaster. I was lucky.

[pancho del rancho]

wat if u use a smaller batter like 1.5 or 3 volts would it still need a resistor

[wobbler]

It's still a good idea to include a resistor. When you power an led from a battery, the battery's internal resistance acts as the limiting resistor. However, depending on the actual led, it may need less or more voltage. I usually stick in a small resistor no matter what (10ohms or so) just in case a new battery has a slightly higher voltage. The 1.5v battery probably won't even light a white led, torches which use only one battery have a step up circuit to raise the voltage to the volts needed by the led. Have a look at Joule thieves here for a simple circuit.

[graphak]

It also helps to know what type of LED you are planning to use. Don't expect to just de-solder one from something else and hope for the best.

[graphak]

This USB greenhouse video is somewhat misleading, and is what I tried to do. In the beginning he shows an LED light / laser pointer just like the one I had, but ends up using something different that involves a circuit that probably has a resistor already built into it. http://www.metacafe.com/watch/795228/cool_usb_greenhouse_for_less_than_10/

[wobbler]

Adding a resistor over 100ohms should be fine. This will give approximately 20mA drive current, which won't blow anything up. You could go down to 47ohms probably. As you go over 100ohms, the led will just get slightly dimmer, but anything between 100-330ohms should be fine, bright enough without any blown leds..

[electricdude107]

The reason that it went out is that your usb port gives out 5v and most led's use around 3 volts. SInce your providing too much electricity to the LED is burned out and cant be used again. You'll need to connect a resistor to your circuit to lower the current from 5v to the voltage you need. And ide recomend using a LED Resistor Calculator to see what resistor you need based on the voltatge that your led requires.

[kingdk2005]

couldnt you just add more than one LED?

[electricdude107]

yes, you could

[hoihoi151]

NOOOOoooo. ADD A RESISTOR. U need to stick a resistor in or u will blow the blub. if its a led

[pancho del rancho]

huh will it just stop working or is it kaboom?

[absolute zero]

i just learned that...i shoved the led in the end of a usb cable and POP goes the weasel...

[mikurej95]

yup, i did. i had a conversation if you read the comments. but the resistor i used really dulled out the light

[wobbler]

You just used too big a resistor. Try a 100ohms, then if it's not blasting go to a 47ohms one, etc. (33>22>10>4.7ohms). LEDs aren't very forgiving of too much voltage!

[YAMAHAMMER]

YOU SURE THATS AN LED?

[mikurej95]

no its not, its a regular light. but it works either way, led or regular light.

[CrashingDutchman]

I think you need a resistor (470 Ohm will do, I think) when using a led. A light bulb might draw too much current from your USB board and in a worst case scenario destroy it.

[mikurej95]

thanks for commenting ill try to update the information as soon as possible

[CrashingDutchman]

After commenting, I think it was a good thing to make one. I often sit in the evening at my computer with the lights off. Sometimes I am trying to find a key on the keyboard but because of darkness I can't find it. I thought that if I had a little light hanging from my monitor, pointed to the keyboard, this problem is gone. I have plenty of spare usb to micro-usb cables laying around and also had a white led. I used a 330ohm resister in series with the led. For the rest, I followed your instructable. The result is that I now have a led power from the USB port on my monitor pointing to the keyboard. It is bright enough to light up the biggest part of the keyboard. Goal achieved!

[Lftndbt]

Almost perfect except for "If you really don't know (*)" That comment I could do without. Otherwise brilliant, simply and to the point. I have been interested in trying some USB hacks and your I'ble has just amde it very clear. I have seen these instructions before in other I'bles, yet this was the clearest explanantion I have read. Thanks.

[mikurej95]

the main reason i made this was because i saw a usb powerd light but for the cost of 20 dollars... so i though, why waste 20 dollars when you could make your own anyways, this is my first instructable so thanks for the tips