How to squeeze a twisted pair for Ethernet 100 Mb

Already with the advent of the first computers, there was a need for a convenient and fast way of exchanging digital data between them. Perforated sheets, magnetic tapes and disks (initially flexible and then rigid), optical media, although partially solved the issue, but their use had one significant drawback - it was necessary to somehow carry the carrier with data to the target computer, so " Convenience "was very arbitrary.

Not surprisingly, in the eighties, it was possible to transfer information between digital devices by establishing a network connection between them (Ethernet). Each computer was equipped with a special adapter (network card), into which the connecting coaxial cable was connected. This allowed data to be transmitted directly, according to the Ethernet 10BASE2 standard (other varieties are less known and not widely used). However, the standard required that the cable's wave resistance be 50 ohms, which made it difficult to eliminate possible damage.

With the advent of a more modern, fast Ethernet, supporting a transfer rate of up to 100 megabits, the coaxial cable was replaced with a twisted pair. In addition to reducing the cost, if you broke any of the veins, you could simply twist and restore the performance of the segment. What is twisted pair? These are several pairs of conductors isolated from each other, twisted in pairs and assembled in a single shell. The conductor of veins can be either solid or composed of thin copper hairs. The first option is trunk, it is usually used for laying in walls up to distribution sockets. The pitch of the plexus in each pair is different, which reduces the focus. The wires are distinguished by the color of the insulation, so there is no need for "ringing".

Sometimes the question arises about what a patch cord is. This is a connecting cable with connectors-connectors at the ends. Usually the length is limited to 5 m, although in the office standard TSB-75 this restriction is removed. If you want to connect two computers together, the patch cord can be purchased at any computer store.

By the way, as a rule, this is a twisted-pair cable. And the buyer does not need to think about how to squeeze a twisted pair, because the connectors are already connected in a certain way (usually PC-PC, cross-connection or "crossover"). Note that many modern devices automatically determine the type of connection and adapt to it. However, sometimes you have to figure out how to crimp a twisted pair. For example, for self- installation of a local network.

In this case, you have to read the appropriate forums and specifications. By the way, in how to crimp a twisted pair, there is nothing complicated - quite a bit of care and accuracy.

You can buy special crimping pliers, their price is quite affordable. Although, with due skill, everything can be done even with nails.

So, how to crimp a twisted pair? It will take the cable itself (for twisted pair 5 categories at 100 Mbps, the maximum distance is about 130 m) and two RJ-45 connectors. Cut the edges of the cable, leveling it and cutting off any damage. Remove the outer layer of insulation. The length of this section depends on the type of connector: the latter must fix a part of the shell, and not hang on some conductors. Pairs weave and level (they should protrude 1 cm). In accordance with the scheme (about this below), insert the wires into the connector. Using ticks we connect the veins with it.

There are two methods of crimping - T568A (company Siemon) and T568B (AT & T). The second species is often used. In the first, the signals are transmitted in pairs "white-green" and "white-orange", as well as orange and green wires. In the second, they are pairs of "white-orange" and "green-white", as well as white and green.

To connect different devices (hub-PC) use the same method of connection on both sides. If you need to connect two computers or two hubs, then one side of the cable is bred by T568A, and on the other - by T568B. Visual layouts can easily be found on the corresponding resources on the Web.

Tip for "lazy": to create a simple network of two PCs, you can buy a ready-made patch cord and a twisted pair cable of the correct length. Cut the patch cord in the middle, clean the ends of the conductors on it and the main cable, twist the wires in accordance with the color coding. Insulate. This solution works successfully at distances up to 140 m.