How a USB Works: the Inside of the Cable

by luster123

233K6139

Intro: How a USB Works: the Inside of the Cable

Hi all, My name is Dexter, I am 15 years of age and this is my first instructable. It will show you the inside of the USB cable. And will show you how to connect a light to it. NOTE: Do not directly connect an LED to a USB cable, use a resistor. I appologise for the poor quality of the photos.

STEP 1: Strip One End of the USB Cable

Strip an end of the USB cable, remember to leave a USB port on one end, show the wires inside (with their coloured covers). The wires should be the same as in the photo below, the red wire = 5 Volts (+) and the black wire is the ground (-), for now ignore the other two wires I will hopefully make an instructable about them at a later stage. We will only use the black and red wires for now.

STEP 2: Connecting the Light

OK firstly, I don't exactly know the type of light I use here, if you do please email me at luster123@gmail.com . Connect the negative(-) wire of your light to the ground (black) wire of the USB cable and the positive (+) wire of the light to the red (5 volts) wire of the USB. Once the wires are connected nicely go to the next step.

STEP 3: LET THERE BE LIGHT!

Connect your USB cable into your USB port and the light should shine like in the photo below.
That concludes this tutorial. Hope this helps you in any way and that you have enjoyed my first Instructable.

39 Comments

pror8ed4gaming 1 year ago

Ok so the pink must be the red, the blue must be the black, and the green and white are the data wires? I sent a pic, take a look and hit me back.

Wind1000100 9 years ago

Can you adjust how much power is sent to the thing being powered over the USB cable?

Otherwise, does anyone know a cheap thing that can do that?

johnwheeler1957 4 years ago

If you wire it through a rheostat switch you can adjust the amount of current that travels through it much like a volume switch highers and lowers volume

thomase3 9 years ago

a potentiometer across just one of the wires (red or black) will let you control the voltage. the current will depend on the device

AlexisG62 7 years ago

so i have a usb similar to this one and i am wondering if there is any way i can cut the usb type B end off and keep the usb type C end and join it to another wire so i can charge my phone. Is that possible?

bchell85 7 years ago

Hahaha that sucks why wouldn't you test it on another USB device or USB wall charger adaptor just to check its not wired wrong and I suggest putting a 100 ohm resistor in series to limit the current to around 25mA. This is an optimal current for an LED to function in most cases. Maybe Invest in nice volt meter, you can fix the USB ports by the way also maybe add an on off/switch

-Ben

LawrenceO8 7 years ago

Awesome instructable by a 15 yr old. Thanks for helping me reuse my power bank which i would have thrown away because the usb ports were damaged. Now I can charge the batteries using an alternative connector.

Lords_Army_Mil_Club-MILSIM_TEAM 7 years ago

Hey man I am 16 and I am doing a project with a Raspberry pi computer and I need to solder some usb cables the wire I have has 2 black wires are those both ground wires.

Onixgato 7 years ago

Hey bro. I am 48 and I bow before you. Great instructable.

dragmex 8 years ago

I have just joined this site and already it has saved me money and helped me fix the power cable for my car camera. The end that plugs in the camera is a micro USB-b type, and when I pulled it out of the camera it snapped inside the metal piece. As the cable is a very long power cable, they are difficult to find, so I cut the same type of connector off an old cable to enable me to use it. Because it has four wires and the power has only two, your diagram helped me identify the USB power cable earth and positive. Although I would have eventually found them, this diagram saved me a lot of hassle, and also the possibility of damaging the camera. Thanks for your help.

VarunT9 8 years ago

Suppose i am going to connect my usb camera to my phone..the length of the chord is about 3 meters..so,phone battery is not enough...If i cut the usb and powering it with an external source..and connecting the remaining 2 cabes (yellow and white) to otg cable ..will it work???If no..please give me an other option...External powering is done using usb port in a car.,

dragmex 8 years ago

I have just joined this site and already it has saved me money and helped me fix the power cable for my car camera. The end that plugs in the camera is a micro USB-b type, and when I pulled it out of the camera it snapped inside the metal piece. As the cable is a very long power cable, they are difficult to find, so I cut the same type of connector off an old cable to enable me to use it. Because it has four wires and the power has only two, your diagram helped me identify the USB power cable earth and positive. Although I would have eventually found them, this diagram saved me a lot of hassle, and also the possibility of damaging the camera. Thanks for your help.

ctguy1955 9 years ago

I was wondering if I would be able to take the nice braided usb cable off of my
razer nostromo keypad, and switch it with the plastic usb cable from my
newly ordered razer Orbweaver Stealth that has not arrived yet ???

Thanks with your answer for this as I do hope its possible.

rcollins6 10 years ago

I need to make a very very important point! Especially because of knexpert1700.

A USB port can only handle 500mA of current, if more flows it may break the computer. Ohms law (V=i*R or i=V/R, i is current, R is resistance) tells you that if you have 5V, and connect some resistance to it, current will be voltage divided by that resistance.
LEDs have a very low effective resistance, and if you hook them up directly across a 5V supply without a resistor in-between (in series) you may draw more than 500mA (or simply burn the LED). If your computer doesnt have current protection, it could break the computer, or at least your USB port.
I would suggest putting a 100 ohm resistor in series to limit the current to around 25mA. This is an optimal current for an LED to function in most cases.

acolak 10 years ago

can i do this with my wireless keyboard? i want to make it wired...there is 1 red and 3 black wires ...red and one of the blac came from where the battery is.

Dunncan 10 years ago

Well. Looking back while I was young, I did not know much. The USB suppose to output 5V with a limit current of 500mA ( just to be safe - it can be higher). Depend on how the circuit is actually build, over drawn current can have various effect - like rendering the port useless.

Read a bit about Ohm's law V=IR before you try it: Given the 5V and 500mA, you would like a resister that is at least 10 Ohm's without a light device. With a light device, the value for the resister can change depend on the lighting device you used - that 10 Ohm will protect the USB but may not be your lighting device - understand your lighting device will help you device a safe good circuit.

alpual 11 years ago

simple and instructive. Thanks.

Flying_MashedPotatoes 13 years ago

yet you dont tell us what resistor to use... not even a link to where they say what rated resistor for what voltage of LED.

Void Schism 13 years ago

Just use Ohm's Law V = IR
or R = V/I = 5/20e-3 (for 20mA diode)
so 250 Ohms
Seeing as electronics isn't an exact science use a 220 Ohm resistor or try using combinations of resistors. Don't be afraid of a little trial and error :)
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