Introduction: How to Power Nearly Anything Off a USB Port
Hi , this is my first instructable so go easy on me :)
So i am going to show you how to power nearly anything off a USB port
This is for the USB competition
USB runs at 5v. The max current you can draw is 500ma. Therefore the max load is 5v x 0.5A=2.5. Watts. (W=VxI) If you try and draw more than 500mA, you may overload the port which will cause it to break
UPDATED PICTURES :)
Just a WARNING to look what your circuit needs if it needs a higher Voltage/current this can break your ports make sure you have got the correct details of the circuit WARNING
Step 1: How Many Volts ?
So to power something off a USB port it has to be under 5 volts as thats how much a USB port gives out so you can check this by ;
Looking at what battery is being used
4 x aaa = OK
4 x aa = OK
USB runs at 5v. The max current you can draw is 500ma. Therefore the max load is 5v x 0.5A=2.5. Watts. (W=VxI) If you try and draw more than 500mA, you may overload the port which will cause it to break
Just a warning to look what your circuit needs if it needs higher this can break your ports
Or looking at a the transformer and see how many votls go in to the circuit ( if your 5 or under your ok )
and you can power of the Port :)
Most electronics nowadays are under 10 V and most of them Under 5V which is good for USB
Step 2: Get Your Cable
Okay so your going to need to get any USB cable this can be a printer cable or a MP3 player cable , your going to be cutting it up so don't pick a cable that you need :P
I chose this :
Step 3: Cutting
So you have your wire , now you will want to cut it to the length you want it , you only need the Male end so the other bit can be discarded
Step 4: Stripping the Wire
Okay you will want to strip the wire to reveal the wire underneath once you have done this there should be 4 wires , you only need the red and black ones as they are the power the green and white are data so they can go :)
Step 5: Soldering and Finish
So you will now want to solder the red wire ( positive ) and the Black Wire ( negative ) to the power in to your circuit or appliance as shown below you can also put heat shrink on the wires to make it neater :
So The Red is Positive ; +V
And the Black Negative ; 0V or -V
Step 6: Testing
Now you've done that you should be able to test it , just plug the cable into a USB port on a computer or laptop of choice , and see :)
Thanks for viewing my instructable

Participated in the
USB Contest
100 Comments
Question 1 year ago on Step 6
Hi
I'm doing a project with require power from the usb port but I'm not using the cable. I would like to tap the power (solder the wire) from the circuit board itself that holds the usb port. The problem is I don't know which is the negative and positive. How do I do it ?
Many thanks in advance for any solution !
Answer 1 year ago
The outer pins are Vcc (5V+ voltage) and Ground. Looking at your photo, and assuming which way is up for the connector, I'd say your left one is GND and the right one is Vcc. Backing this up: ground usually goes to a large "ground plane" of copper on the board, and the others tend to go to wire-like traces, which is clearly visible under the right-hand pin.
Anyway, plug in a random USB power source and confirm this with a multimeter if you have one.
Question 1 year ago
So could a person power a 3 volt ANR headset with it without any chance of smoking the headset?
Question 1 year ago
Whitch voltage on the item I'm trying to power is the one I'm looking for? The box says 100-240v 50-60Hz , but then beside that it says "output voltage 5v" is it the output voltage I need to be 5v and lower? If so then This should work correct? Also does it make a difference if I cut the power cord of the device and solder my USB wires to the cord rather then soldering it directly to the devices powerboard? Thank you for your time!!!
Question 1 year ago on Step 6
How do you accomplish this on a USB-A female 3.0? what do you do with the white,green, blue, yellow, purple and orange wires?
Question 2 years ago on Step 6
Ok I have a 9V 300ma Radio Shack Mixer. They don't make anymore and folks are selling them for 4 times what they cost NEW from the RS store. The Mixer is powered by a 9V Battery. Sad part is if you forget to turn it off, you get a Dead battery. There is a 9V 300ma power connector at the back of it. The part I'm having issues with is the Transformer of the Power Supply creates a hum in the audio. I'm wondering if I can get away with attaching a USB to it and powering the Mixer, sure I'm losing 4Volts... But it should work... Still..???
Question 3 years ago on Step 6
Sir i wanted know that i have a 4 usb power hub port and I don't have a data transfer usb port, so there's a connection for DCv can I change the DC connection to AC so that the cable from my hub can be used as data transfer cable please help
3 years ago
Can I just solder the black and red wires to + and - wires from a 3V power supply (a small generator I)? This is for a school DT project.
Question 3 years ago on Introduction
Can i use my usb port like a cord u plug up to a wall
Question 4 years ago on Step 6
So I have a string of led lights run on 3 X 1.5 aa batteries. I buy a gizmo from ebay that lets me reduce the usb input voltage 5v down to 1.5v OK lights are on and bright BUT they are shimmering. Is this right. If I swap the wires over does not work at all SO ???
Answer 3 years ago
You need to draw a certain amount of current to make the USB port work. Put a resistor in parallel with the buck converter to fix this
6 years ago
sir can I have help ?
my laptop usb port don't produce enough power output so even mouse I can't use it all of my port in laptop didn't work i cant copy any file to/from flash drive, when I insert optical mouse it just blink the red light and didn't recognize at all how can i fix this sir
thanks.
sorry for my bad english
Reply 4 years ago
your laptop USB outputs should produce enough energy...
there might be something internally wrong. IE bad capacitor, poor solder, etc..
ill try to get back to you on this with some solutions.
6 years ago
If I have portable usb charger can I assume that it will work in the same way as a usb port on a computer for this tut ?
Reply 6 years ago
Some portable USB chargers give more power, but yes.
Reply 4 years ago
Generally the ones i see have 1 Port at 5V and a second at 2.5V.
i just made a wireless, rechargable LED RGB Lamp using a Portable USB charger that i got for $5 from walmart.
Question 4 years ago on Introduction
What if I'm powering 1.5v will this work. Plus how could I run this through my AUXILIARY on my car stereo?
4 years ago
so i have a wall powered led light, and the socket only outputs 4V, so will i be able to wire up a usb to this light?
4 years ago
Thank you, This helped further my Mad Engineer complex. Much appreciated.
5 years ago
Thank you! Informative, concise and useful.
I have used your Instructable and came back to do it again. This time I will take pics ;) too much of a hurry last time.
My Project, take battery operated string lights (LED) and use USB power instead.. and by the way They Light up My Room, so in a way I am using them to "power my house" LOL