Homebrew Power over Ethernet (PoE)
Saturday, July 14, 2007 3:48:53 PM
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.
Power over Ethernet
Knudde.be (my inspiration, in Dutch only)
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.