USB Powered LED/ Christmas Lights





Introduction: USB Powered LED/ Christmas Lights

This shows how to power an LED or some Christmas lights from the USB port on your computer.

Step 1: Get Your Materials

For this you will need the following:

Old USB cable with a male end (like an extender that you can buy at the dollar store)
An old set of battery operated Christmas lights (also a dollar store product)

Step 2: Get Out Your Wires

Cut one end of the USB cable off. You may wish to give yourself as much cable length of the male side of the cut cable. there are 4 colored wires inside the large wire. expose the red and black ones. these are the power wires that would power the USB device. the white and green ones are for information transfer and aren't used.

History Lesson:
A USB cable puts out about 5 volts of power, just enoguh to power most LED's and battery operated Christmas lights (they usually take 2 AA or D cell batteries which are 1.5 volts a piece. 2 batteries = 3 volts, so a USB cable has more than enough power but not too much)

Step 3: LED

The LED has two legs the long one is positive (+) and the short one is negative (-). The wire from the red coated wire from the USB cable is the positive, wrap that one around the long leg of the LED. (if you have money you can use a soldering iron) and wrap the wire form the black coated wire around the short leg from the LED. put tape or something of the like on one leg to prevent crossed wires ( it can cause a spark, personal experience) plug the USB cable into your computer and it will light up. Simple.

Step 4: Christmas Lights

The same applies with the red and black coated wires here. Take the battery pack from the Christmas lights and snip it off. strip the wires.plug the USB cable in and touch the wires from the lights to the red and black wires, striped. when the lights light up, unplug the USB and twist the wires together. tape one of the wire connections to prevent crossed wires. There you go!

Step 5: Enjoy

this is a neat project to spice up any computer area. if the USB cable is left plugged in, when the computer turns on and off the lights will light up with the computer. it is nice to turn on your computer and have your desk light up! Also, this was my first instructable and hopefully, they will get better from here on out =P



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    Cool. I have one of these battery powered things. 4 AA? I think not. And this way, it will only be on when I'm sitting there. Thanks for the info.

    1 reply

    Glad you like it! Honestly, I forgot I had this 'Ible. =P

    Love the idea and effort but have to agree with Itsgoofytime. You really should add a resistor as they are cheap and easy. Just put one in the circuit and the led will last forever. Here's the formula. Good luck! //rick//

    R = (VS - VL) / I

    VS = supply voltage
    VL = LED voltage (usually 2V, but 4V for blue and white LEDs)
    I = LED current (e.g. 20mA), this must be less than the maximum permitted

    hey i followed your instructable (very nice btw) but my LED only blinks four times and then nothing. At first it was on more and the device manager thingy popped on and off installing it and stuff ( i run win xp ) but after a few reconnects it does nothing :( any ideas?

    2 replies

    it could also be that hes over powering the light maybe thats it it did it to me before i connected a resisitor but eventually the led will burn out sad but true i use my green led as a backlight to my xbox 360 lol works fine

    hmm, did you do anything with the green and white wires? if so, disconnect them they are for data transfer. Also check to be sure that you have no crossed wires, that would mess up the circuit. thank you for the compliment and I hope that this helped.

    check out my first instructable that i posted over two years ago: usb Christmas lights.

    you might also check out the link i provided showing where i got the idea from.

    looks like we started at the same place. hope to see more from you.

    Add Resistor. Add Resistor Add Resistor. Add Resistor Add Resistor. Add Resistor

    I just did this for a small tree on my desk at work. I used a 10-light battery powered string from the dollar store and a spare usb cable. Works great!

    does it have to be battery operated ones or can you use regular ones?

    1 reply

    The battery ones operate on 3 volts of power and you get 5 volts out of the usb port. I've not tried it with regular ones but i think that they require more power

    This is all wrong. USB puts out 5VDC, with a max of 500mA, which is close to blowing out the port. You need a resistor on the LED so it wont burn out, which is apparent in your LED picture. The LED appears to be yellow indicating a burning LED die. It should be green, as indicated by the green colored lens. Revise.

    1 reply

    my bad, the Picture was bad and the LED wasn't burnt out, the Christmas light was the main part, I just had an LED lying around