Homebrew Power over Ethernet (PoE)
Saturday, 14. July 2007, 15:48:53
It works! I've just hooked up my self made power over ethernet contraption. I've been interested in the capabilities of power over ethernet because I wanted to get rid of the butt ugly wall wart for my Linksys WRT54GL in the livingroom. I found an excellent how-to on the web that's intended for short lenghts of CAT5 cable only.So today I assembled my own low-tech injector and splitter from two ethernet coupling modules, and two pieces of wire with the right connectors already mounted. Did some cutting, drilling, soldering, painting, crimping etcetera and hey presto: my very own PoE contraption for less than 10 euros! Commercially available solutions, such as the WAPPOE12 from Linksys, cost 40 to 50 euros. Not bad eh!? The picture shows the splitter at the WRT54GL side of the cable, here the power and data is separated.
Now my WRT54GL gets its power from downstairs, where my cable modem is situated. The power is transported over the approx 5 meters of CAT5 cable between modem and WRT54GL. Works like a charm.
The upside is that now the power adapter will not be accidentally knocked out of the outlet anymore. The downside is that I had to unplug my WRT54GL from power thus "losing" a 30 day uptime.
The idea behind power over ethernet is that by using the unused four wires in a standard CAT5 cable you can have data and power transport over a single cable. Very nice if you want to mount a wireless access point in a location where there's no power outlet in the vicinity, or if you want to get rid of the power adapter hanging from the outlet socket. One thing to remember is that if you want to want to have power over ethernet over a large distance you'll have to take a loss of power into account. Long cable runs will result in a lowered voltage at the end of the cable, your piece of equipment might not want to work with it.
Links
Power over Ethernet
Knudde.be (my inspiration, in Dutch only)
UPDATE
I've found some how-to's that show you can have power over ethernet with an injector only. Splitting power and ethernet is then done inside a WRT54G/GS/GL by soldering two wires. Cool, but it requires opening up your router.
Links
FON board
Byte Club
Abrahamarama
WIDGETIZE
fearphage # 14. August 2007, 20:46
Saw your post on the dd-wrt forums. Always nice to see another Opera user
Would this work with any router with a 12v adapter? I have a WRT300N running dd-wrt right now and it also has a 12v adapter. Just curious...
treb # 14. August 2007, 20:58
treb # 14. August 2007, 21:33
FYI, I can not be held responsible for any damage or loss you might suffer. Proceed at your own risk.
STEP1
The inline connectors are going to modified to be used as an power&data injector and power&data splitter. This method has wide range of applications and will likely require no modifications if you ever buy a different accesspoint or if you want to use PoE for a different application.
You need:
2x plastic inline connectors
a lenght of wire
power connectors
tools
solder + soldering iron
wire stripper/cutter
drill + drill bit
STEP2
Open up the inline connector and disentangle the wires. Isolate the wires that will be going to conduct the power. In this case wires 4&5 will become + (positive), wires 7&8 will become - (negative). Cut these wires on one side only. Don't mess with the data wires! The colours of the wires inside the connector aren't universally the same or follow a standard colour coding. You've got to figure out the right coloured wires to be used for PoE yourself. Don't screw up here, make VERY sure you've got the correct wires!
STEP3
The inline connector that will be used as the injector has got a power-in connector. The power from the adapter will be plugged into this connector. The other inline connector has a wire coming out of it with a power connector which will be plugged into the accesspoint.
STEP4
To prevent damaging equipment both splitter and injector get a colour-coded side indicating which side is carrying power and data and which side only carries data. A marker or some hobby paint will do.
Last picture: above right is a normal grey CAT5 cable coming from a hub/switch/modem etc.. The black wire is coming from the power adapter. Both cables are plugged into the injector. The blue CAT5 cable carries both data and power. Bottom left is the splitter, power and data are separated again. The accesspoint receives power and data over two separate cables.
treb # 14. August 2007, 21:49
WRT54G's run on 3.3v and 5v internally, so a slight drop in power will not result in insufficient power for the router.
Don't know about your WRT300N. Google's your friend.