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

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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.

usb.pdf(595x841) 14 KB

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.

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azimovismayil3 months ago

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

Can anyone please tell me the working principle of this USB tester
cholerah211 year ago
sir laptop got like this hhh
m1s73r3 years ago
When does the red LED light up?
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 mode1 year ago
Pánico mode is right, Thanks for answering him.
bobbock4 years ago
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 bobbock3 years ago
I believe they are 1/8W as they are the same size as a 1N4148 diode.
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_sanches3 years ago
kkkk, muito bom.
jupiter23 years ago
good job!
beaver843 years ago
cool! :D
inhaos3 years ago
your schematic is cool
here is a perfect solution for you

mased0074 years ago
Hello. How to ironing method do? please
MoritzB4 years ago
Does it only check the voltage at the red and black connections, or does it also check the data lines?
dwyatt10454 years ago
I was wondering what the wattage is for the resistor
brunoip (author)  dwyatt10454 years ago
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.
kenobr1004 years ago
how much did this cost to build ?
brunoip (author)  kenobr1004 years ago
I think it would be less than 2 dollars.
xtagz4 years ago
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..
You don't have to be a pro to get that PDF, did you try clicking it?

i need a circuit diagram.

can u help me.....
Taran6064 years ago
i dont have any 3v3 zener diodes any other parts i can use
Taran6064 years ago
Insted of using 5 resistors can't u use one 100 ohm resistor and one 46.5k resistor
brunoip (author)  Taran6064 years ago
Why explain and can u make a smaller compact version plz
Why explain abd can u make a smaller version that's more compact
Taran6064 years ago
In the 5th pic or the last one what are the extra leeds on the side for and are they inportant
brunoip (author)  Taran6064 years ago

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

regards, Bruno

Can I make a diagram because this one has to many resistors and I want to make it smaller
Leuh4n4 years ago
Fa, que trabajo posta :O
vhhp4 years ago
Brunoip, Good work. Liked your product and also your sensible replies. ..regards..
MASKELF4 years ago
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
ozzymon4 years ago
buenisima la idea, increible tu ingenio!!! segui asi y ojala que tenfçgas suerte con tu usb tester!!
brunoip (author) 4 years ago
An user sent me a photo of his prototype.
It worked perfectly.
Here it is:

papajay_234 years ago
what is the introduction of this usb tester??can i use thiis in thesis proposal?
vyncynt4 years ago
I have been wanting to have one since I got my tech job. this is very neat, thanks brunoip.
fpm20004 years ago
Nice instructable! Since I don´t have the skills to build one, I purchased a similar device from
Did you design the pcb by yourself?
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