The Smallest USB LED




About: Sometimes my Instructables are few and far between, but I try to make them as well as I can. Hopefully you can be inspired or helped by the content in them!

Here is the smallest USB LED you've probably ever seen! It uses a USB plug made with a piece of perfboard, so you should already have everything needed to make this. No cutting up USB cables here!

This kind of homemade USB plug could also be used for other things, like repairing USB cables.

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Step 1: Supplies

All you need for this project is:

A Soldering Iron
150-200 Grit Sandpaper
1k Resistor
Blue LED (Other colors will work just fine, too)
Small Piece of Perfboard
X-Acto Knife

I used a 1k resistor because I just wanted a nice looking light, not a blinding one. ;P Feel free to use a different value if you choose.

Step 2: Score and Sand

The first thing we need to do is make the USB plug. Luckily, the traces on the perfboard are spaced apart just right so that they will work for USB ports.

If your piece of perfboard isn't already in a strip like mine, cut some out by scoring the perfboard with your X-Acto knife, then breaking it apart.

Take your strip of perfboard and score it four traces in with your X-Acto knife (Four USB pins = Four traces). Break the piece off so you have a squarish piece that fits in a USB port. If it does not fit right, sand it a little bit to make it the right size.

Step 3: Bend and Cut

Now you need to bend and trim the leads on the LED and resistor.

Bend the positive lead of the LED 90 degrees out, and bend one of the leads on the resistor down and out, so it will line up with the bent LED lead. Check the pictures if you're a little unclear on what to do; after all, they ARE worth a thousand words each.

Clip the leads down so that there will be enough left for soldering, but clip them enough so that they will not get in the way of anything. Make sure everything lines up with the two outer traces on your perfboard, like in the second picture.

Step 4: Put It Together

Now solder everything together.

First, you need to fill the perfboard traces with solder. This is where bridging actually comes in handy. :P
You only need to do the two outer pins, but later I did all four for good looks.

Next, solder the LED and resistor together.

Solder the LED/Resistor combo to the perfboard. Make sure you get the polarity right. In the pictures below, the negative side of the LED needs to be on the left side, not the right. Make sure you don't mess that up, or your USB LED won't light.

Step 5: Plug It In, Plug It In

Congratulations! You've just finished the worlds smallest USB LED! ((Patent Pending) Not really :P)

It might be a good idea to sand the contacts after soldering, to remove oxidization and make it look nicer.

Plug it in, and watch it glow! These are easy to make, and very small, so many of them could fit in a pocket at once! I've made several for some of my friends and teachers. :) These are good for using unused USB ports, and they look cool, too! Have fun. ;)


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203 Discussions


11 months ago on Step 1

How to maier the output voltage when we conect any resister with led etc.


2 years ago

nice. Did a similar thing.

My daughter broke her previous usb charging cable, so i decided to keep it for myself. Made a pretty nice led flashlight.


3 years ago

Sandisk has smaller pd than this led


4 years ago on Introduction

"The Smallest USB LED"

Looks like 5mm, a 3mm LED would be smaller!


But seriously, why not SMD?


5 years ago

If you use an SMD LED you can make it even smaller! :)


5 years ago on Step 4

i made this for my dad last christmas! thanks for the idea. i just used an old usb plug and removed the parts i didnt need instead of making a custom end but its basically the same thing.


5 years ago

Awesome idea! this is my first prosject so far on instructables! :-) (NOT SO GOOD!)

Kante Tech

5 years ago on Introduction

I'm thinking of attaching a fishing wire or string so that I can easily pull out the board when needed.


5 years ago on Step 5

smart and very good idea.the most important thing is it's really very easy for DIY.

thanks. I want to try to DIY one for myself.

Luigi Pizzolito

6 years ago

I'm building one as soon as I get the ressistor

Luigi Pizzolito

6 years ago

Cool instructable!!!

It would be even cooler to build one with surface mount components and a mini USB.


6 years ago on Step 5

Very nice....I used a unused USB in my TV to power a bluetooth Wii bar... I might use this design for say...? I have an idea!! ill share later...BUT



USB ports are 5 volts. A typical blue or white led is around 3.2v, to be safe, we'd use 10ma on it,
so using so by going (5-3.2)/0.01= 180 Ohms

So using any resistor above 180 ohms is absolutely safe, but using a resistor higher than maybe 1000 Ohms will not be very bright/not light up at all.

However, I commonly use 100 Ohm resistors for 5v, and I have no problems with that.
It just means I get 20ma instead of 10


11 years ago on Introduction

How come in the 1st image and 2nd to last image, the resistor shows brown, black, red, gold OR gold, red, black, brown... I can't really tell, but in step 1, your yellow note over the resistor says color code: Brown, Black, Red?

Do you know how you can figure out which way it goes?

Like lets say there are colors WXYZ.

The resistor is eithe WXYZ or ZYXW, how can you tell?

(In the image, is this the resistor you're using?)

4 replies

if you are asking, no the polarity of the resister does not matter.

no, it does not matter if the resister comes first or the LED

and you read resisters from the band that's closest to the end toward the gold ban (sometimes silver or wide-stripe brown)

these are brown, black, orange, gold = 10 K ohms with a ±5% tolerance


Reply 11 years ago on Introduction

Why do they go on positive, Ive never figured this out, if electrons flow from negative to positive wouldn't it make sense for them to go on the negative?