Tutorial – How to make a Molex to USB (power only) cable

theshadow27

How to make a Molex to USB power only cable
By TheShadow May 2005 Rev 1.0
Originally posted for XoxideForums.com
Re-posted here for Search Purposes only! ;)

There comes a time in every modder's life when they find some cool, useless, USB powered trinket that they want to put inside of their computer without wasting a USB port. This guide will show two ways to make a USB to Molex power cable that will let you do just that.

If your device has a "USB-B" port on it (the square boxy connector on the non-computer end of a standard cable) -OR- if you don’t mind cutting off the "USB-A" (the one that currently plugs into the computer for power) connector, then you can use the first way. It will come out nicer in the end, and can be made to a custom size.

However if you ever want to use your device outside of a computer again, then your probably not going to want to cut off the connector. For these less hard core modders out there, I have included a second, less intrusive way of doing this.

First things First

Let’s get down to business with the first way. You will need 1 spare USB cable (with male A and B ends), an old male Molex connector (doesn’t matter where it is from) and:
>soldering iron, solder
>heatshrink (best) or electrical tape
>wire clippers of some sort

Let’s start this off with this scrap male Molex connector that was cut off from its female counterpart many moons ago... (If you don’t have as big of a junk bin as I do, I would recommend something like this)


We don’t need the 12v pins; they are just going to get in our way. But I am way too cheap to buy a Molex pin remover! So grab a BIC pen (standard ball point. no, ink color doesn’t matter) and get cracking:

What you want out of that whole ordeal is the ink reservoir. The back (keyword, back, you don’t want ink on your Molex pins!) fits perfectly over the pins! imagine that... (well you don’t have to, here is a pic)

So you push it in all the way, then pull the wire out from the back. The 2 wires you want to pull are 12v and the ground closest to 12v. It should look a little something like this:

And when you’re done, you are left with a beautiful 5v only Molex connector:



Now moving right along to our USB cable. It has 2 ends, an "A" and a "B":

Since the "B" end plugs into your fun toy, we want to keep some slack on that end for wire management. I decided to keep the whole thing, and just cut off the "A" end. Mmm, USB, tasty

I assume everyone knows how to cut a wire...

I’m going to put aside the "A" end for something later. Anyway, we now have 4 wires, and a shield:

You want to keep the red and the black wire. Unless you are colorblind, this should be pretty easy:

So, let’s sit back and think. We have 2 red wires, and 2 black wires. Gee, I wonder what we are going to do with them

So get some heatshrink (electrical tape works if your lazy/cheep/don’t have heatshrink) and a soldering iron out...
Note: you have to put the heatshrink on BEFORE you solder.

And with one magical flick of a cheap lighter, you have a brand-spankin-new USB-Molex power cable!

So you don’t want to cut up a cable, eh?
well there is another way to do it. You will need a USB motherboard adapter (like this, any computer store will have it) and a resistor of any value. Also:
>a soldering iron/solder
>electrical tape

So you just bought the USB thing. Okay. We are going to assume that you are up to here:

if you are not, follow the steps above. You now have a Molex connector with two wires.
At first, I was going to cut off the end of the USB thing. This would make it exactly like the steps above. If that’s how you want to do it, you can figure it out. The following way keeps all parts reusable, and doesnÂ’t require heat shrink.

The resistor doesn’t matter, as long as it has leads. Bend them like this:

Solder the Molex’s wires to it:

Now, you can cut off the resistor, leaving only its leads:


Cut the leads down to about 7mm:


Okay, lets see what we can dig up… This has two connectors molded into one, but it doesn’t matter. We will only be powering one


here is the motherboard end of it:


Since most people wont have the male version of this plug, I think a using resistor leads is an elegant solution. You can hook the red to the red and the black to the black by sliding the resistor leads into the female motherboard connector:


If you don’t have at least one resistor lying around, I guess you’ll just have to cut off the box like connector and solder the wires directly. (like the cable above)

Now make it happy with electrical tape, making sure to wrap both leads individually before wrapping them together, and then finally a third wrap to the connector:


Remember that spare "USB-A" connector that I cut off? I'll use it just to show that this works (0 ohms = connection):


so now you can power your disco ball, electric toothbrush, iPod, ect... without wasting an actual USB port. Minimum cost = $0.0, maximum cost = $5

BeaMeR

Awesome tutorial I will be using this for sure in the future.

jfkfhhfj

kool, Great toutorial

Greell

yar, rocking tutorial, went all out with the pics and everything. more people need to do that :)

buckley

fantasmic... as i said before :)

theshadow27

Hey, if anyone wants to request a tut, just let me know!

buckley

what are you good at that you think other people might benefit from?

e13Oxide

hey man, is it possible to do it the other way round, get a molex to get power from a usb port? i want to power some cathodes outside my comp, is it possible for me to plug ina usb and get power toa molex?

Sleeper Cell

Thats a very good tutorial. There's step by step pictures :)

theshadow27

no, USB provides 5v at 500ma, and a CCFL uses 12v at 1.7a

sorry :(

e13Oxide

ok, no prob, just wanted to see if it might be possible

Granthos

Sweet tutorial, this loks like a very good one, i hope to use this sometimes.

DualCPUs

Loved that tutorial , thanks for the updates too :)

x86box

Now what if I wanted to power a Laptop drive from a USB port? Like if I had an e-sata port and I wanted to use a 2.5" Hard disk on my laptop - but externally.

furball zen

Any of the adapters/enclosures you get from Xoxide, eBay or Best Buy etc, will be powered by the USB port itself. No need for hacking power to it. Most of the ones you get off of eBay will have a reg USB cable, with 2 A ends on it, one is just for power, the other power/data so you can then use a second USB port for additional power.

Like this:

x86box

Ok, Here is what I'm trying to do.

I have a CF to Sata II reader, I want to make this into a cf to e-sata reader basically.

I'm just wondering if I can power the CF Card from USB with a Molex to USB cable / sata power- instead of just using a AC->DC 12V. I would think this could be powered from FW400 / USB / FW800.

I work with a Professional Cinema camera that records to CF Cards. Sometimes we may need to shoot 25 Cards worth of 16GB CF Cards. And the Production would only rent 4-5 cards so you have to constantly recycle them.

furball zen

its possible, What model reader are you using? I can make a better solution if i know what you are working with. Also, by the way youre talking, im guessing you want to use this in the field vs having to go home to your PC to d/l the data? I could be wrong, but without looking it up, e-Sata is powered, so you only need one cord instead of power/data.

(nvm, i looked it up, the 'e' refers to external, not powered)

x86box

I have two 'rigs' I take into the field. One is a MacbookPro, Where I use an E-sata express card adapter. I usually keep My Drives off the e-sata and download cards over fw800.

I'm considering making a portable port multiplier where I would need power (If I were to use the laptop rig). So that I could hook up multiple Card readers and E-sata Drives hooked into the express card adapter.

My other Rig is a Quad Core 2, with LSI Raid card hooked to a SAS 4u 16 Bay Array. This machine is a Hackintosh. I dont really have any issues with it, I can hook up many sata Readers / Drives- if needed.


For now I'm using a AC power adapter to get Molex, I'm about to add the port multiplier. I'm waiting for it in the mail.

furball zen

Ah i see. Yea not really any way to do that. USB only puts out 5v@1A max, but usually around 500mA, i dont think it would have enough current to sustain it without a psu/wall wart. I know of plenty of Macs that cant handle a reg 2.5" drive enclosure even with the extra USB port.

x86box

Yeah, like Mine!