USB Led Light





Introduction: USB Led Light

About: Full time student in the Industrial Electrical Tech program. Wanna be redneck, driving my 93 ford ranger 4x4. Back yard mechanic... well heated garage mechanic in the winter. Avid DIYer, off road newbie. ...

USB led light

Step 1: Materials

USB plug and cord
Blue LED (any other color will work too)
100 ohm resistor
Case or housing to hold the led ( I used a cheap mini keychain flashlight housing)

Tools Needed to do this project

Soldering iron
Screwdriver to take apart case

Step 2: Assembly

Open keychain flashlight housing and remove all components. Solder positive wire of USB plug to the positive of the LED, solder the negative lead to the 100 ohm resistor, and solder the other end of the resistor to the negative of the LED. Install components in case.

Step 3: Test It

Connect to a working USB port and it should light up. :)



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    i also have a USB cable but in that there is no output from black wire so connected to the green wire and by using a multimeter  it shows 5v and i connect LEDs to it without using resistor my PC is showing that the USB device is not recognizable please help me 
    and i can't afford another USB cable

    thanks so much, but what i would like to know is, the voltage of the usb for multiple LEDS, can some one help me plz, and email me on

    1 reply

    Go there :

    Good luck! :)

    Hello! To power up a blue light which is (2.5V), you have to put a resistor of 125 Ω, because if you put a resistor of 100 Ω, you will burn out your blue led. here's the formula : (Vc - Vf) / 20mA (1 led) *1000 = 125 Ω. If you put up a resistor size of 100 Ω : ((5 - 2.5) / 100 Ω) * 1000 = 25 mA, a single led is 20 mA, so your will burn out your LED.

    thank you!

    were do you get those male usb plugs i only find female

     windrago its called auto hot key. google it

    1 reply

    awesome thanks!

     is possible to turn the light on/off through software?
    I mean writing an app in C# for example.

    1 reply

    You can do it...just disable that specific usb port...most modern languages support it, even script languages...

     so would this work if i tried to plug it up to my cell phone?

    i cant find leds anywhere and im looking for one so i can make a keyboard light

    4 replies

    try "the source" by circuit city. i'm not sure if they have "the source" in the us tho(if thats where u live)

    circuit city is gone from us I think but they have radio shack its cheaper to buy stuff in radioshack though (im from canada)

    ya our radio shack went out of buisness when i was like 4. so now i have to eithe buy stuff from the internet or go get ripped off at the source.

    try radio shack. they should have drawers of electrical components

    heck looks like u bought it