Introduction: USB Tester

Picture of USB Tester

This simple device allows you to check the correct working of the USB ports of any computer, using a green led and message from your operative system.
It will allow you to test the proper assembly of any port without risking any expensive device.
If you normally work fixing computers this is a must in your tool kit.

Ps: I'm from Argentina so let me know any grammar mistake

Step 1: The Circuit

Picture of The Circuit

The circuit is very simple using only some discrete components.
The operation is simple, you connect it to the USB port, if it's okay, the green LED is lit in all its intensity and you will have a message from your operative system telling you than a USB device has been detected. If the polarity is reversed the red LED is lit in all its intensity. Any other combination causes lit one of the two LED but very dim.

You will need:
The PCB (see step 2)
The USB connector (see step 3)
Two 22K resistors
One 1k resistor
One 100 ohm resistor
One 1.5 k resistor
One 3v3 zener diode
One 1N4148 diode
Two leds (green and red)

The diagram was extracted from this forum (in Spanish):

Step 2: The Board

Picture of The Board

The PCB is very small and simple.
I made it using the method of ironing.
PDF file annexed contains the design ready for printing.

Step 3: The Connector

Picture of The Connector

This project seeks to be economical so you're not going to buy a connector. We will recycle a cable that does not work.
First we remove the plastic guard with a knife.
Then remove the remains of cable and solder it new terminals.
Finally I soldered two terminals to the metallic body to keep it firmly attached to the PCB:

Step 4: Soldering Components

Picture of Soldering Components

The components are easy to weld.
Try not to overheat the diodes and not allow shorts in the PCB.
Use the second image as an assembly guide.


gmrad (author)2016-10-26

Clever hack!

Aaaecm (author)2016-07-29

Great project! Very useful. This is just what I needed. Thanks!

ortegacomputacion (author)2015-07-27

Hey Bruno, thanks for sharing, this is exactly what I was looking for. I'm planning to use a bicolor led, the one which turns green or red depending which way the current flows. anyways, I'm from argentina too, and I have a small grammar correction for you, "Try not to overheat the diodes and not allow shorts in the PCB." should say : "Try to not overheat the diodes and don't (or do not) allow any shorts in the PCB" brunoip, you are legendary , here in Argentina. also se dice easy to solder, weld is for big uniones.

TheGimpAddict (author)2010-06-26

Did you design the pcb by yourself?

brunoip (author)TheGimpAddict2010-06-26

Yes, I did.
Using PCB Wizard.

AtLarge (author)brunoip2015-07-20

Thank you Brunoip. I made mine on a breadboard. Seems to work work fine although I only had 15k resistors on hand not the 22k you had specified. Need you to design one for testing a USB 3.0 port now. :-)

MildredGreen (author)2015-06-09

very good article for IT students like me :) thnx

azimovismayil (author)2014-11-30

very good.I could make it at 4th time :D

Machintosh1984 (author)2013-10-23

Can anyone please tell me the working principle of this USB tester

cholerah21 (author)2013-05-13

sir laptop got like this hhh

m1s73r (author)2011-11-16

When does the red LED light up?

panic mode (author)m1s73r2013-04-24

Q: "When does the red LED light up?"

A: when USB polarity is reversed. this little mistake can easily be done on auxiliary or remote ports on desktops. those are ones that connect to motherboard through cable, for example:

plugging in camera or phone etc is an expensive way to test for this.

brunoip (author)panic mode2013-04-24

Pánico mode is right, Thanks for answering him.

bobbock (author)2010-11-01

What wattage resistors are you using, or does it make a difference?

I'm new to building electronic devices, and thought this would be a good one to try. When I went to get the supplies from my local store the first question they asked was what wattage. I bought 1/4 watt ressistors assuming that the voltage of a usb port is around 3.3 volts.

Thank you for the project and any help you can give.

ionic (author)bobbock2011-11-08

I believe they are 1/8W as they are the same size as a 1N4148 diode.

Blip-Blip-Duino (author)bobbock2011-07-12

Wattage(sounds like cabbage, haha) doesn't really make a difference. In this case, seeing as you're using an USB port, with 1/8 you're more than fine. BTW USB uses 5 volts DC, usually @ 200-450 mAh.

os_sanches (author)2011-08-07

kkkk, muito bom.

jupiter2 (author)2011-07-15

good job!

beaver84 (author)2011-05-06

cool! :D

inhaos (author)2011-05-05

your schematic is cool
here is a perfect solution for you


mased007 (author)2011-03-17

Hello. How to ironing method do? please

MoritzB (author)2011-02-12

Does it only check the voltage at the red and black connections, or does it also check the data lines?

dwyatt1045 (author)2011-01-26

I was wondering what the wattage is for the resistor

brunoip (author)dwyatt10452011-01-26

The smallest you can get.
1/4 or 1/8 watts shloud be fine.
There is no problem if you want to use a big one.
Regards, Bruno.

kenobr100 (author)2010-12-01

how much did this cost to build ?

brunoip (author)kenobr1002011-01-26

I think it would be less than 2 dollars.

xtagz (author)2010-08-20

Sir.. Can u send me some other links for the PCB design..?? i cant DL the pdf file because im not a pro members... thanks..

Minifig666 (author)xtagz2010-11-17

You don't have to be a pro to get that PDF, did you try clicking it?

manish_1october (author)xtagz2010-09-29

i need a circuit diagram.

can u help me.....

Taran606 (author)2010-10-27

i dont have any 3v3 zener diodes any other parts i can use

Taran606 (author)2010-08-19

Insted of using 5 resistors can't u use one 100 ohm resistor and one 46.5k resistor

brunoip (author)Taran6062010-08-19


Taran606 (author)brunoip2010-08-19

Why explain and can u make a smaller compact version plz

Taran606 (author)brunoip2010-08-19

Why explain abd can u make a smaller version that's more compact

Taran606 (author)2010-08-18

In the 5th pic or the last one what are the extra leeds on the side for and are they inportant

brunoip (author)Taran6062010-08-19

Read the text:
" keep it firmly attached to the PCB"

regards, Bruno

Taran606 (author)brunoip2010-08-19


Leuh4n (author)2010-08-16

Fa, que trabajo posta :O

vhhp (author)2010-08-10

Brunoip, Good work. Liked your product and also your sensible replies. ..regards..

MASKELF (author)2010-07-10

excellent creation Bruno after creating it worked perfectly and as expected, is a great tool because I lost a USB memory port through a poorly connected, thanks! add a photo of mine

ozzymon (author)2010-07-07

buenisima la idea, increible tu ingenio!!! segui asi y ojala que tenfçgas suerte con tu usb tester!!

brunoip (author)2010-07-07

An user sent me a photo of his prototype.
It worked perfectly.
Here it is:

papajay_23 (author)2010-07-07

what is the introduction of this usb tester??can i use thiis in thesis proposal?

vyncynt (author)2010-07-06

I have been wanting to have one since I got my tech job. this is very neat, thanks brunoip.

fpm2000 (author)2010-07-02

Nice instructable! Since I don´t have the skills to build one, I purchased a similar device from

zilcho (author)2010-06-22

I'm a complete noob on electronic stuffs so could you tell me what kind of iron on thing you used to print the circuit board.

brunoip (author)zilcho2010-06-23

You can use any type of iron.
Instructables has several posts explaining how to do it.
Regards, Bruno

TSC (author)2010-06-22


The nerdling (author)2010-06-20

hello heres a tip: use a rule for your lines but s is syill good

brunoip (author)The nerdling2010-06-21

I prefer it that way. Thanks [i]A la criolla[/i] Regards, Bruno

About This Instructable




Bio: Robots and video games...
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