Wednesday, 16 July 2014

Making Cables – Part 3 – USB Powered

We’re a little bit out of order. I decided to make the USB power cable before the planned second article (2 Pin DuPont Male to 2 x 2 Pin DuPont Female). I’ll get on to that next.

Practically, this project is the same as the 9V Snap project. The only practical difference here is that there is some wire cutting involved in this project that is slightly more complex than the previous article.

As this article builds on the previous one, refer to the previous article for detail on some of the steps that I don’t detail here.

Firstly, I started with an old USB cable for a redundant mobile phone.01_OldUSBCable

This cable has been sitting in my parts/cables box for a while and it’s time to give it a new lease of life.


As you can see, this is a non-standard device end for a USB cable. Hooray for proprietary implementations.

I simply cut the device end away from the cable with some side cutters.


There’s always a moment when you do this that you think to yourself … what have you done? Now I can’t power that … oh yeah, I recycled that phone more than 10 years ago.

Now strip the outer insulating sheath away from the cable core.


Initially, I made this 10mm, but I then went back and stripped another 10mm away so that I had enough exposed wire to strip the internal wires properly.


For this USB cable, there was an inner lining of a metal sheet wrapping the core wires., you can just strip this away by hand.


By convention, there are 4 insulated multi-strand wires inside a USB cable. This cable also had another ground wire of uninsulated multi-strand wire in there. I think that this was a continuous ground from end to end.

The four insulated multi-strand wires are:

  • Black – Negative wire for ground connections
  • Red – Positive wire – typically 5V
  • Green – Negative DATA (DATA-)
  • White – Positive DATA (DATA+)

A possible variant is Orange (Positive), White (Negative), Blue (DATA+), Green (DATA-).

As our cable isn’t going to carry data, the Green and White (as well as the uninsulated) wires are cut away.


Try to make this as neat as you can, you don’t want accidental signals interfering with the Positive or Negative lines.


I then stripped away 5mm of insulation from the end of both wires and then tinned the exposed multi-strand leads. These leads are quite thin and are easy to work with.

After the leads were tinned, I then tinned the DuPont Female connector between the end wings as I did in the previous article (9V Snap). Once both the lead ends and the connectors were tinned, I soldered the leads into the connectors.


Then I removed the connectors from the strip and crimped the connectors to the wire for a sturdy connection.


In the previous two pictures, you can see that I have already slipped the shrink tube onto the cable. This is so that I don’t have any problems when it’s time to tidy up the job.

After that, it’s a matter of slipping the connectors into the housing. Remember, I use the arrow on the DuPont housing to indicate positive.


I intend to completely cover the wire on my USB cable, so I won’t be able to refer to the lead colour to tell me which is positive and which is negative.


As you can see, when the shrink tube is shrunk, you cannot tell which lead is which. So the convention of the arrow indicating Positive is very useful.

The last part of this is to connect the cable to power and to power a device to make sure that it’s all hunky-dory. The cable is about 40cm in length, so it should deliver slightly less than 5.1V.


Bazingo, the device is powered. By the way, the USB cable is connected to a USB AC Adaptor, rather than to my computer. If you are unsure of the amount of power that will be drawn by your device … blow up an AC Adaptor, they cost less than a computer. Ideally, you would attach the USB cable to your multimeter to check out how much power it is delivering, just to be sure and because it is easy to do, right? When I tested the cable with the multimeter, it detected a voltage of 5.07V … so there you go, safe to connect to my computer.

Well, as you can see, converting a dead USB cable into a useful 5V power cable is easy and not very time consuming. Overall, this project took about 5 minutes to complete, so don’t expect this to waste your weekend doing it … plan to do other stuff too!

If you wanted to use the cable from a dead mouse … simply cut the mouse away from the cable (it’s just another device end).

No comments:

Post a Comment

Paypal Donations

Donations to help me to keep up the lunacy are greatly appreciated, but NOT mandatory.