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POE: Power over Ethernet confusion

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techidave:
I am confused about using POE devices.  Does the device like an access point, need to be specially made for POE?  I understand how a POE switch or POE injector pushes power over the ethernet cable.

What I don't understand is how the device on the other end takes the power from the ethernet cable to actually power the device.

I am sure someone here can clarify this for me.

Dave

4wd:
The device has to either be made to utilise PoE or you can use a breakout box to separate the power feed from the Ethernet cable before connection to the device.

Here's an example on ebay along with a connection diagram: PoE Passive Injector/Extractor

POE: Power over Ethernet confusion

techidave:
Thanks, 4wd.  I was thinking I would need something on the device end but didn't know what.  When I googled it, I came up empty.  But didn't know what I would need is called a POE extractor.   :-[

40hz:
4wd beat me to it! ;D (4wd - the Man! :Thmbsup:)

There's a really good article on  DIY PoE projects done by the NYCwireless non-profit. It shows diagrams, photos, etc. And it provides everything you need to roll your own - or provide you with enough technical detail to be able to better buy one. For a one-off project, it's probably easier and not much more expensive to buy an injector/splitter combo unless you have an adequate quality 'wall wart' lying around. Link to article here.

Important Note: If you do build your own, pay close attention to voltage drop since sending DC current over any distance can create a fire hazard if you exceed safe maximums. Especially with something as thin as the 24AWG wire your standard CAT-5/6 cable uses. And if you don't know enough about electricity to know what voltage drop is, you probably shouldn't be building your own. ;)

PCRush has a good selection of PoE components on their website. They carry all the majors, so you can either shop there or use their site to get tech specs and comparative pricing numbers.

Luck! :Thmbsup:

-----------------------
Standard disclaimer: 40hz has no affiliation with PCRush.

4wd:
4wd beat me to it! ;D (4wd - the Man! :Thmbsup:)-40hz (October 02, 2011, 07:25 AM)
--- End quote ---

The advantages of being in the light while ya'll in the dark ;)

Important Note: If you do build your own, pay close attention to voltage drop since sending DC current over any distance can create a fire hazard if you exceed safe maximums. Especially with something as thin as the 24AWG wire your standard CAT-5/6 cable uses. And if you don't know enough about electricity to know what voltage drop is, you probably shouldn't be building your own. ;)
--- End quote ---

Very good point  :up:

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