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.