Make Your own PoE - Injector and Splitter

Make your own Power Over Ethernet Injector set for $2 in Parts

Ever need to install a network hub, camera, or other device in a location that did not have a locally available power outlet? Need to ‘extend’ the power cord?

In this tutorial, we’ll be building a very cheap Power Over Ethernet Injector out of $2 in parts. This will let you place your power supply for your device near the ethernet hub, where power is plentiful, and place the device itself hundreds of feet away.

Caveat: There is a Power Over Ethernet (POE) standard, which we’re ignoring, as this particular injector setup is for legacy products that do not offer POE support.

The standart states the minumum power supply should be:

• 44V DC / 350mA = 15.4 Watts

so for standart compatibility (802.3af - PSE Mid-Span) you would have to use a 48V DC power supply with equal or more than 350mA.

In my case, I’m making it for my wired network camera, a Hawking HNC-210, which is generally alwayssituated farther away from the power outlet. It comes with a fairly short (6′) power cable, which is an odd product design consideration. Since you’d generally put a camera at eye-level or higher, this cable is really too short for most installs.

Parts List: $1.80 US:

• 1. RJ-45 pass-thru connector 80¢
• 2. 2.1mm power jack and plug 50¢
• 3. spare (short) working ethernet cable 50¢

The first item we need is an ethernet (RJ-45) pass-thru connector, for patching 2 ethernet cables end to end. It is available at many local retailers/computer shops. I grabbed a few at BG Micro for 80¢ a piece. The nice thing about these is you’re getting 2 pre-wired RJ-45 connectors for very cheap.

A bit of man-handling to pry the two halves apart, and we have 2 halves of our POE injector. Simply cut all 8 wires at the half way point. You can tell which wire goes to which pin by looking at the inside of the now disassembled connector. Take notes of which wire goes to which pin, using a regular ethernet cable as a reference. There are 8 wires, which we need to be grouped. 4 wires are for ethernet, 2 wires for Positive Power, and 2 wires for Negative Power (Ground).

You’ll need to strip and tin all the ends of each tiny wire on both pieces. We’re basically hand-wiring connections for power and ethernet in each connector. Use the wiring table later in this article to make the connections. While you’re here, why not put some shrink tubing over each wire to protect them from cross-connection later.

I need more Power, Scotty!

Next up in the arsenal, we need the power jacks to pass the power from the AC wall wart to the camera. I checked the camera, and it used a standard 2.1mm power jack. I picked up 2 example jacks from an electronics supplier.

The top set is an inline jack and plug, which costs $1.20 for the set. The bottom set is an panel mount jack and plug, which costs considerably less, at only 50¢ for the set. First, check to make sure they work together.

I soldered 2 wires to the power plug that were equal length to the ethernet dongle I already had on hand. I slipped some shrink tubing over it, then made the connections.

With the Power Connections, polarity doesn’t matter as much as making sure you don’t flip the circuit with your cable build. If you decide blue is tip and brown is ground, stick with it at both ends of the injectors – not following this is a sure way of destroying the device you’re powering.

In my case, I connected the tip of the power plug to BOTH the 2 blue wires, and the shield to BOTH the 2 brown wires. On the other side, I connected the same to the tiny panel-mount power jack. I then used hot-melt glue to mount the panel mount to the remaining plastic frame.

Why connect to both wires? In case one wire fails in a regular ethernet cable, it’ll still work. Plus, there is less voltage loss with the larger combined wire. The total voltage loss is negligible for most installs. If you find your device isn’t working properly, check to see if the cable is too long, and the voltage is too low to power the device.

Next up the complex ethernet wiring….

Common straight-through ethernet cables only use 4 wires out of the 8 inside the sheathing. The common wiring in illustrated below.

Take your short working ethernet cord and cut it in half. You’ll want 2 short 8″ pieces, with the working ethernet RJ-45 ends still attached. Strip off an inch at the cut end, and expose the 8 wires inside. Cut the blue and brown sets of wires off. These are unused in this application – these ‘dongles’ will be the ethernet in and out connections.

So the ethernet wires (in most cases, you should check) that we’ll be using to pass the ethernet traffic is the 2 orange wires and the 2 green wires, which fall on pins 1, 2, 3 and 6. Simply connect the pin 1 on the ethernet dongle to pin 1 on the ethernet connector jack, and so on through the other 7 wires on both sides.

Finished Power Over Ethernet Injector and Splitter

I covered open connections with shrink tubing, then tucked all wires inside the tiny connector cases. I then used hot-melt glue to seal up the open ends of the connectors, and now I have a matched pair of Power Over Ethernet Injectors!

Installed at the Camera End

Simply attach one end of your 100+ foot long ethernet cable to this end, place your camera anywhere, with only one cable feeding to it.

Installed at Hub/Switch End

At the other end, at the switch/hub (also suitably close to a power outlet), simply plug it into an available port, plug in the power supply, then the camera feed line.

Shield your eyes! Cable Porn! Shocking double-69 cable-on-cable action!

Based On: http://underdesign.wordpress.com/2010/04/07/make-your-own-power-over-ethernet-injector/

PoE Standart Details: http://www.ieee.li/pdf/viewgraphs/introduction_to_poe_ieee802.3af_802.3at.pdf

How to wire Ethernet and Console Cable (Cisco - Roll Over)

Cables form layer 1 of the network — the physical layer. Properly connecting cables is fundamental to healthy network communication. Faulty connections could interrupt service or cause packets to be dropped. Without a clear understanding of cabling, you won’t be able to troubleshoot or design your LAN or WAN. Additionally, knowledge of cable types is important for certification tests like the Cisco CCNA/CCENT.

Cabling basics for network admins

• Your cable works at layer 1 — Physical of the OSI Model. Also at that layer are the 1’s and 0’s that traverse the cable as an electrical or light signal (depending on what type of cabling you are using).
  
• Unshielded twisted pair (UTP) copper cable is used for many functions in network cabling: Ethernet, Serial, ISDN, Console, and more.
• While you could put different ends on a UTP cable, typically it will have a RJ45 end with 8 pins.
• With a normal Ethernet cable, the wires run straight through, from one end to the other. Straight-through cables are used to connect a PC to a switch, as in Figure A-1 and Figure A-2. Where each one uses one off the cabling standards, the T568B and T568B

 Figure A-1 - Straight-Through Cable 

Figure A-2 - Straight-Through Cable 

Graphic Courtesy of Cisco Systems

• With a crossover cable (Figure B), the source and destination of the UTP wires are crossed. This allows you to use it to connect a PC to PC, switch to switch, or router to router.
  
• In a crossover cable we use both off the cabling standads, T568A and T568B, one in each end, if one end uses T568B the other uses T568A, and vice-versa.
  

Figure B - Cross Over Cable 

Graphic Courtesy of Cisco Systems

Now, how is cabling for Cisco routers and switches different?


Cisco console and AUX port cabling
There are a few differences between Cisco cabling and other network device cabling. Two things immediately come to mind:

• Cisco routers, switches, and firewalls use a special “rolled” cable for console and auxiliary port access.
• Cisco offers intelligent serial cabling.
  

One of the most confusing things to Cisco newcomers is the concept of the console cable. Other SMB and home-networking devices don’t usually have a console port. With those devices, they receive a DHCP IP address and then you can configure them over the network from there. With Cisco devices, there is no IP address on the device, and you must first use the console port and console cable to configure the router, switch, or firewall OOB (out of band).
The Cisco console cable is a special cable. It isn’t wired like an Ethernet cable. However, if you didn’t have a console cable, you could cut off the end of a straight-through Ethernet cable, change the pin out, and recrimp it to make it a console cable.
Below, you can see the pin out of a console cable. The console cable is a “rolled” cable, because if you look at the pins from one end to the other, it is as if the end was rolled over (the order is flipped), as in Figure C.

Figure C - Console Cable (Rolled Cable)

Graphic Courtesy of Cisco Systems

Traditionally Cisco console cables were RJ45-RJ45 and then you would use a RJ45-DB9 adaptor to connect it to your PC’s serial port (COM port). Today, new Cisco devices come with console cables that have a DB9 adaptor integrated/molded to the cable on one end (Figure D). Keep in mind that the data moving across the console cable is serial data (not Ethernet).

Figure D - RJ45-DB9 adaptor

Graphic Courtesy of Cisco Systems

For those equipements tha don't have an integrated DB9 ports, here how you can make your own DB9 adapter:

Click on the images to enlarge

While what I said above concerning console cables is true for most Cisco devices, there are variations on the console cable. For more detailed information about Cisco console and AUX port cabling (including the pin-out for a console cable so that you can make your own), see this Cisco document Cisco Cabling Guide for Console and AUX Ports.

David Davis has worked in the IT industry for 15+ years and holds several certifications, including CCIE, CCNA, CCNP, MCSE, CISSP, VCP. He has authored hundreds of articles and numerous IT training videos. Today, David is the Director of Infrastructure at Train Signal.com. Train Signal, Inc. is the global leader in video training for IT Professionals and end users.

Taken From: http://blogs.techrepublic.com.com/networking/?p=649
and added some stuff about the cabling standards (like here)


Another good reference for building ethernet cables is:
http://www.ertyu.org/steven_nikkel/ethernetcables.html