Kind of misleading.<p>1) This isn't "PoE" in any sense of being able to power a PoE-compliant device. It's hacking up an Ethernet cable to carry voltage on 2 pairs not used for 10/100 Ethernet.<p>2) The article recommends a 7805 power regulator if you need to step down 12V to 5V (as in the example). While this would work, 780x regulators essentially throw off the unwanted excess voltage as heat, and total heat output is going to be a factor of the voltage drop and current. 12V-5V for a router (could be 1A or more) could end up being quite a bit of heat. You'll likely need to use an adequate heat sink with it. There are more efficient (and still easy to use) switching regulators available.
This is a neat hack for 100mbit networks, where only 2 of the 4 twisted pairs are in use. Unfortunately, this wont work for gigabit networks, where all 4 twisted pairs are used for data transfer.
You can buy adaptor lead sets from ebay and other suppliers that plug onto the data cable ends and give you an Rj45 port and a DC plug/socket pair - this is a much neater and quicker option.<p>eg: <a href="http://linitx.com/product/passive-poe-injectorsplitter-set/13305" rel="nofollow">http://linitx.com/product/passive-poe-injectorsplitter-set/1...</a>
This is a very bad idea from a system architect point of view. You would probably get another cable in there in the same amount of time, while having a much higher test coverage for your parts.<p>Physical connectors are there for the same purpose as type enforcement in strongly typed languages. They make things "just work".<p>Plus, what if you are ill and you want someone else fix an issue? What if you want to scale up the network later and need all wires?<p>If you don't hack you will need no docs.
We do this all the time with devices carrying the DMX protocol. As others have said, it works only in networks that aren't using all 4 pairs of ethernet cable -- which is the case in DMX.<p>The biggest issue when doing this is always sizing the power supply to the receiving device.
Wouldn't this method, especially with a switching power supply, introduce a lot of interference in the cabling?<p>Any pickup or noise in the power supply and router would be inductively/capacitavely coupled to the signal cabling inside the cable's shield, right?
Reminds me of the etherkiller: <a href="http://www.fiftythree.org/etherkiller/" rel="nofollow">http://www.fiftythree.org/etherkiller/</a>