LAN Crossover Adapter

 

Anyone who has networked two or more PC's will probably know this common problem. The other day I had to use a crossover cable but I only had a patch LAN cable. I thought "Surely there must be a way to make a LAN cable the reverse of the type it is". Turns out there is, you can buy little adapters on the internet like this one. But me, I couldn't be stuffed buying one and waiting for the delivery, when I can make one in about half an hour.

 

 

Step 1: Collect the neccessary bits

I dunno about you, but I just got an old LAN cable and a old(er) network card that didnt work anymore. I also used a soldering iron, multimeter (optional), wire strippers, a phillips screwdriver, a knife and some good-old gaffa tape.

Step 2: Break the neccessary bits

I used a screwdriver to remove the faceplate of the network card. This was the easy bit. It then took about 10 minutes of careful desoldering to remove the actual socket. I won't lecture you on how to solder (return the favour) so if you want to learn, go here. I used a pair of wire strippers to cut the 50cm Cat5E cable in half and strip the wires. Once I did that, I needed to find out the correct pinouts.

Step 3: Find the correct pinouts

Incase you didn't guess, the one on the left is the crossover, and the one on the right is the straight-through patch cable. On the socket that I pulled of the network card, I used a multimeter to find the pins that represented the correct Cat5E pins. From a top-down perspective, the pins that I desoldered is in the above order. This will probably vary from each network card, so use a multimeter and find out the correct pins!

Step 4: Wire the pins to the correct wires

The next bit is a little tedius - I had to get the right wires to the right pins. By looking at pinouts.ru, I found that this is the correct order for a Cat5E wiring. I chose to use TIA/EIA 568B wiring because is seems to becoming more popular. The centre bit is the only bit most people need to know about. for example, the first pin from the LAN cable now goes to the third pin. It's not exactly hard, but you do need to double check before soldering. The colours are as follows: Remember I am using the bottom image because I want TIA/EIA 568B Standard.

Step 5: Soldering

Once that I was ready, after soldering each pin I wrapped it in some tape to prevent the solder bridging the already too-close-together pins and to prevent the wires breaking and shorting.

Step 6: Wrap ups

Once that I soldered all the pins, I simply wrapped the tape in more tape.

That's it!

Mine works, and your's should too. If it doesnt, it means that you either shorted the wires out with dodgy soldering, or you didnt get the pins right. I tested mine both on a network cable tester and then between two pcs. Simply plug a patch cable in and it becomes crossover, or plug in a crossover and it becomes patch. Excellent for both Network Administrators, and the budding LAN party-goer. If you have any suggestions, send them to: