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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Signing UpStep 1: 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): http://www.ucontrol.com.ar/forosmf/proyectos-en-general/probador-usb/








































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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:
http://www.usbman.com/Guides/Belkin_F3U001.jpg
plugging in camera or phone etc is an expensive way to test for this.
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.
I believe they are 1/8W as they are the same size as a 1N4148 diode.
here is a perfect solution for you
http://www.inhaos.com/product_info.php?products_id=29
cheers!
1/4 or 1/8 watts shloud be fine.
There is no problem if you want to use a big one.
Regards, Bruno.
i need a circuit diagram.
can u help me.....
Read the text:
"...to keep it firmly attached to the PCB"
regards, Bruno
It worked perfectly.
Here it is: