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Crossover Dongle

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Picture of Crossover Dongle
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.
 
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Step 1: Parts

Picture of 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.
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Very handy.

Pasit6 years ago
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?
srmousse Pasit6 years ago
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.
rahulait Pasit4 years ago
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....
festec2 years ago
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
http://web.archive.org/web/20010224082835/http://www.directconnect.bizland.com/cables.htm
GitarGr8 (author)  festec2 years ago
Yep, I wasn't claiming to have invented this, just wanted to show people how to make them. :)
festec GitarGr82 years ago
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
Mojo_JoJo3 years ago
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
dongle.jpg
tsedlmeyer7 years ago
Great instructable; however, there is one problem with the cable produced.

Unfortunately this cable will not work properly for gigabit ethernet. Gigabit Ethernet utilizes all four pair on the cable. The cable presented here only crosses two of the pair. The correct pinout can be found here. Unfortunately most commercial crossover cables are also not correctly pinned for gigabit ethernet use.

If you use one of these incorrect cables you will still get connectivity on a gigabit ethernet interface; however, you will only get 500Mbs instead of 1000Mbs.
If I use the the 1000 T base crossover, will this work with 568 A and 568 B system?
Gigabit internet does not need a crossover anyway. You can plug any normal network cable and it will just work!
The spec does not require NICs to detect whether they need to internally cross. Most gigabit ethernet NICs along with many newer fast ethernet NICs do and indeed do not need a crossover cable. Some NICs do not and some disable this feature if you manually set the speed and duplex. Many people manually set speed and duplex for connections such as switch to switch or firewall to router.
I should have said may give you connectivity up to 500Mbs. Some chipsets will use the two pair to give you 500Mbs. For instance if you connect two Cisco switches they will do so. Some NIC's will fall back to 100Mbs and some may not provide a connection.
GitarGr8 (author)  tsedlmeyer7 years ago
Great point, I'll edit the instructable to make a note of that.
of course! so logical... this should be a standard tool. Is your name Spock, by chance?
GitarGr8 (author)  maxstevenson5 years ago
Ha, sorry to disappoint, but it's not my name. Plus, I think this is something Scotty would have come up with.
hintss GitarGr83 years ago
or the doctor or Data or teh interwebz
va1cho4 years ago
ethernetcablewiring.com/ethernet-crossover-adapter

I think this tool is better choice because you need to do nothing and price is cheap.
GitarGr8 (author)  va1cho4 years ago
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!
DraakUSA4 years ago
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.
Pasit6 years ago
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??
GitarGr8 (author)  Pasit6 years ago
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.
static GitarGr86 years ago
Respectfully, you where a bit sensitive that day, as I noted no criticism.
GitarGr8 (author)  static6 years ago
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....
static6 years ago
I had the local network guy make me one of these several years ago. I didn't have the tools nor the cable. I dont know if RS carried them or not. but RS is 50 mile round trip for me if the do. Having the local make me one kept money in my pocket. Good instructable
Randy Lahey6 years ago
Wow, this is crazy. I made one of these a few years ago when i used to be a computer tech. Very handy. When i made mine I thought to myself "Holy Fuck! what a great idea! I wonder if anyone else thought of this?" It's definitely a must-have for any computer/network techs out there. I'm suprised you can't buy these. p.s. It will also turn a crossover cable into a straight cable.
GitarGr8 (author)  Randy Lahey6 years ago
Apparently you can buy these.
n0ukf GitarGr86 years ago
But the point of Instructables is DIY and share how you did it. In some cases it's cheaper to buy, in others it's cheaper to make, and in yet other cases, the project isn't available for sale anywhere.
maker126 years ago

nifty!

vaiden6 years ago
Man, this is a great instructable. Just the other day I had to cut a damn cat5 cable and swap the tx and rx wires to hook two routers together. Im gonna make one of these bad boys. I dont have gigabit nics, so even though I have a gigabit switch ,I can hum right along without both pairs. Great idea!
I don't think the keystone jack grabs onto the outer sheath of the cable. This presents a strain relief problem. It might be a good idea to roughen up the sheath near the keystone jack with some sandpaper and dab some flexible drying epoxy around to bond it with the keystone jack. This comes at a loss of the ability to rewire the jack, but should make a more reliable connection since keystone jacks are intended for racks where the wires won't be flexed often.
Wolver7 years ago
Now why didn't I think of that? Nachos Bellgrande props to Gitar
rimar20007 years ago
Very useful. Good idea, expandable to other applications.
qpmarl7 years ago
I made one a thems once. Still have it. Never actually used it though. I'm all wireless these days.
Spokehedz7 years ago
Most punch-down tools have a second end that you use by flipping around the connector. The ends are double-ended as it were.

Also, you can get a retractable CAT-5 cable that will spool up the cable into a neat little box. very handy, and keeps the box nice and neat.

http://tinyurl.com/2ra2wh - Example of retractable cat-5e cable
benjgvps7 years ago
Now if only my Powerbook 150 had ethernet..
mrmath7 years ago
You get geek points for carrying a straight to crossover converter. I've seen them for sale commercially, but your version offers two advantage. First, the ones I've seen have to have two cables plugged into them, one on each side, so you still need two network cables. Second, you get extra geek points for having made it yourself.
The one I bought didn't require 2 cables, but it didn't have any slack like this one does. It was very hard to unplug because of that.
Here's the one I have/had (I don't know where it is)
http://www.thinkgeek.com/gadgets/tools/7ef8/
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