Crossover Dongle





Introduction: Crossover Dongle

About: Pseudo-intellectual college dropout, with a penchant for snobbery.

If you're like me you've got a bah-jillion cables floating around in your computer bag. I got tired of having to have two separate types of cat-5 cables, straight and crossover, so I came up with this little gadget that will turn any straight cable into a crossover cable.

Step 1: Parts

Here's all the tools/parts you will need:

1 x RJ45 Crimp Tool
1 x Push Down Tool (some keystone jacks come with their own)
1 x Wire Strippers
1 x Cat-5 Cable
1 x Cat-5 End
1 x Keystone Jack
1 x Hand with at least one finger and opposable thumb

Step 2: Prepare the Cable

Strip back the outer insulation on one end of the cable, so you've got about 1.5" of wire to work with. This will be the "male" end of the cable.

Untwist each of the four pairs and arrange them as follows:

1 - Orange / White
2 - Orange
3 - Green / White
4 - Blue
5 - Blue / White
6 - Green
7 - Brown / White
8 - Brown

This follows the 568B wiring schema which is what I always use when wiring up patch cable. To make normal 10/100 base crossover cable one end needs to be wired 568B and the other end needs to be 568A. Basically what you are doing is swapping the orange and green pairs from one end of the cable to the other, hence the term crossover.

**Note that for gigabit ethernet you will need to cross the blue and brown pairs as well.

Trim back the excess wire, give your self about .5" to .75" to insert into the Cat-5 plug.

Step 3: Crimp

Insert the wires into the cat-5 plug. Make sure that the "notch" side of the plug is facing down as you slide the wires in. Otherwise, you'll have created your own unique wiring scheme, which is cool, but no other existing devices will understand it.

Once the wires are in the plug, insert the whole <william-hung-voice> she-bang </william-hung-voice> into your crimp tool.

If you're smart you bought a ratcheting model. If you're a cheap bastard like me (ex g/f's words, not mine), then your's doesn't ratchet either, and you'll need to squeeze down and hold for a good ten seconds.

Step 4: Wire the Keystone Jack

Your keystone jack should have some sort of legend that will show you how to wire it up. To wire this jack 568A I had to wire:

Green / White to pin 1
Green to pin 2
Orange / White to pin 3
Blue to pin 4
Blue / White to pin 5
Orange to pin 6
Brown / White to pin 7
Brown to pin 8

Wait a minute, that's exactly how the diagram shows 568A is wired! What a strange coincidence...

**Again, in order to utilize gigabit transfer rates you will need to swap the blue and brown pairs, so instead of the above it would be: Brown / White to pin 4, Brown to pin 5, Blue to pin 7, and Blue / White to pin 8.

If you've got a shop that you can pilfer other people's tools from, then go steal... err, borrow a nice push down tool, which cuts the wire for you automatically.

Some keystone jacks come with their own tool, but it doesn't cut the wire for you. For that you'll need a pair of diagonal cutters, or just use a knife.

Step 5: Done

Put the cover on the jack. Poof, you're done. Now you can network two PCs sans a hub or switch.



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    42 Discussions

    i wasnt trying to be critical it was supposed to be a question?? and wtf's the difference between a stait cat5 cable and a crossover cable, and whats a cat 5 cable?

    3 replies

    cat 5 cable is the proper term for the most commonly used network cable (the thing that plugs from your internet router to your computer... similar to a phone cord but with more pins). The purpose of a crossover cable is to eliminate the need for a network hub (a device used to network several computers together) when connecting two computers together (or even xbox's for that matter). Basically the crossover cable crosses 4 of the wires so that the two computers (xbox's) can talk to each other.

    I just wish to clarify here "the thing that plugs from your internet router to your computer... similar to a phone cord but with more pins" that refers to all Ethernet cable not just cat 5. And the cables work by having computer 1's output go into computer 2's input and vice versa. And Pasit, Cat5 is a standard of cabling, rated at 100Mbps and 100 meters, being theoretical.

    to be more precise, a cat5 cable is having 5 twists per 1 inch of the cable. its a standard... similar to this we have cat3 cables, cat4,cat6 cables....

    that type of cross cable over has been around for years ! if you need one for giga bit then you cross over the blue and the brown pair... I have been making them for years. here is a picture of one in the internet archives back in 2001
    you might have to cut and paste the link

    2 replies

    Yep, I wasn't claiming to have invented this, just wanted to show people how to make them. :)

    Jay Stapleton in Thunder Bay phoned me back in 1999 asked if I could make him one ....I think he is the first to come up with that type of cross over cable !
    Way to go Jay

    I made mine like this, it accepts two straight cables and crosses them. I find this easier to carry in a laptop bag. It originally had two female connectors connected in stright through configuration, it was pretty easy to open and cross the pins of the socket. HTH


    Ha, sorry to disappoint, but it's not my name. Plus, I think this is something Scotty would have come up with.

    Actually I like this one the best, but then if you just buy something, you miss out on the enjoyment and experience of building something yourself.

    i agree with you GitarGr8, the thinkgeek one is superior however that takes all the fun out of it.. buying stuff isnt allways the best way!

    With newer equipment you almost never need this, since most new equipment will auto-detect.  However, this is handy to have for equipment that doesn't.  I've had one in my toolbox for several years that I use when I need it.

    i dont get the point of this instructable, u just turned one "outy" end into and "inny" end. so the "outy" end of the other cable that would be plugging into the orange "inny", couldnt it just go strait into the port on the computer istead of through that thing??

    3 replies

    Do you know the difference between straight and crossover cable? This turns straight cat-5 into crossover. Crossover is needed for many different networking applications, the most common of which is to connect two PCs with just the cable. Try doing a little research before being so critical.

    Respectfully, you where a bit sensitive that day, as I noted no criticism.

    How dare you call me sensitive!! J/K, it couldn't possibly be that my engineering job has worn down my patience for the uninformed....