Instructables
Picture of The Smallest USB LED
The-Smallest-USB-LED_Tech.jpg
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.
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sanneelh24 days ago
Awesome idea! this is my first prosject so far on instructables! :-) (NOT SO GOOD!)
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Kante Tech1 month ago

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

Kelly Smith made it!6 months ago

This was fun! Thanx :)

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littlebeastie7 months ago

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.

Ploopy1 year ago
I'm building one as soon as I get the ressistor
Ploopy1 year ago
Cool instructable!!!

It would be even cooler to build one with surface mount components and a mini USB.
ZaneEricB1 year ago
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

VERY NICE!!
how to calculate resistor value for against usb port output voltage against. plz help
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
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?)
DSC05156.JPG
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
thank you
(removed by author or community request)
agm88 agm881 year ago
brown black orange 10k ohm and it doesnt matter the polarity eathier
this message was intended for beggieners
It doesn't matter witch color first, but they do have to go on positive.
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?
1up (author)  emuman4evr6 years ago
... Don't they flow from positive to negative? And it actually doesn't matter if the resistor goes on the positive or the negative terminal.
emuman4evr 1up6 years ago
I read in one of my dad's electrician books that it was believed that electricity flowed from positive to negative but then proven it actually flowed from negative to positive. So it doesn't matter?
1up (author)  emuman4evr6 years ago
Well, a quick Google search confirmed that you are technically right. Electrons are negatively charged, therefore they have a tendency to flow towards the positive end of the power supply.

But, in electronics, it is said that they flow from positive to negative, so as not to be confusing.

And again, it does not matter if the resistor is hooked up to the positive side or the negative side.
gomibakou 1up1 year ago
Electrons are the only that can move... remember the atomic structure, protons and neutrons are "glued" together to form the nucleus and electrons are orbiting "around" it. Protons can't move, because you have to break the nucleus for that... and it's called nuclear fision xDDD (used in current nuclear power plants). Elecricity is only the electrons flowing trying to achieve a electric equilibrium... or electric potential if you like it. As only the electrons can flow... the direction of the current must be from the negative terminal to the positive, or i should say from the terminal with more electrons to the terminal with less electrons (it's "like positive" since it is not so negative as the other terminal)... that is the -resuming- the physics behind. I prefer thinking it flowing from positive to negative xDDD
Berserk87 1up5 years ago
this is what you guys are talking about.<br/><br/><a rel="nofollow" href="http://www.rkm.com.au/ANIMATIONS/animation-graphics/circuit-diagram.jpg">http://www.rkm.com.au/ANIMATIONS/animation-graphics/circuit-diagram.jpg</a><br/><br/>Conventional Flow, and Electron Flow.<br/>
1up (author)  Berserk875 years ago
Ah, yes, perfect. Thanks for the diagram.
gomibakou 1up1 year ago
Current flows (well really the electrons flow) from negative to positive. But, for study, usually its represented as the opposite: from positive to negative, but it's a representation not the true physics behind. I learnt this way and i'm fine with this, regardless i know the real current flows from negative to positive.

For a resistor, since it's a pasive component with no polarity, it doesn't matter where is the positive or negative voltage. The key is the POLARITY. It hasn't.
A LED has... a capacitor has or hasn't xD depends on the type...
Metallic colors always go last, like gold, or silver.
The gold band comes last, and is there on almost all resistors. The first three bands give the resistance and the last band (gold) gives the tolerance. The resistor he is using in this instructable is Brown-Black-Red. The resistor in your picture is not the right type, you need a 1k resistor (Brown-Black-Red) and yours is a 10k resistor (Brown-Black-Orange).
resistor-band.jpg
Oh okay, so gold is always last? That's how you can figure out which order it is?

Thanks, that helps a lot!!! :-)
Sometimes it's silver instead. But the premiss is the same.
1up (author)  Grey_Wolfe6 years ago
A gold band means 10% tolerance, silver means 15% tolerance. No band means 20%.
dark sponge 1up6 years ago
Actually, silver is 10% tolerance, gold is 5%, red is 2%, brown is 1%, and none is 20%
1up (author)  dark sponge6 years ago
Oh, yeah, whoops. I must've gotton confused. I just realized I wrote 10% for gold.
Grey_Wolfe 1up6 years ago
Didn't remember the exact tolerances, been a few years. But it's good that you through it out there.
Duh, how about "threw" it out there. Not sure what planet I was on right then. lol
YAY I havenoidea what your talking about!
Depending on the LED you use, you'll need a different resistor. If you know the rating of the voltage and amperage of the LED, you can figure out the necassary resistance. The equation is R=V/I. R is resistance, V is voltage and I is amperage (not sure why, there's no "I" in ampere, nor is there one in team :) ) I just finished an USB powered LED lamp in an Altoids Smalls tin. Not very "small" compared to this, but it came out well. It has a flexible neck and a 7000mcd LED.
1up (author)  GorillazMiko6 years ago
I just have always remembered that gold is always last, sorry for the confusion! :)
LAS1 year ago
The LED and Resistor connections are reversed between STEP 4 and STEP 5 images

Step 4 have Cathode (-) [LED Flat Side pin] on right
Step 5 Have Cathode (-) [LED Flat Side pin] on left

In both the resistor is on the Anode (+) side of LED so it appear one set of photos was done with a Mirror.

PS: Step 5 with Cathode (-) GND on left is the correct way around ;-)
http://www.addonics.com/technologies/usb3_tutorial.php
i would imagine its greatest purpose would be to test usb polarity and if its working or not? i love it none the less.
haha this is fantastic!
kevins821 year ago
Thats awsome i woud like to make video about this small project when parts arrive, if you allow?
1up (author)  kevins821 year ago
Of course, I don't mind at all. :)
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