Not sure if this is the right place for such a topic, but i’ll give a try.
Basically the topic could be a question, but let’s be more specific. Is it possible, or someone has ever tried to power an ethernet switch using PoE?
The distance between switch and PoE injector would be about 50-60m.
You can power just about an DC device via PoE as long as you don’t over drive the CAT5 wiring… I’m not sure on the volt/amp limitations of the cable but a simple search should provide this info…
Get a passive POE injector, and then find a Power supply that meets the requirements of the switch. Then all you need to do is pull off the positive and negative pairs, and get the appropriate plug to plug into the DC power source on the Switch… What I’ve done in the past is just clipped the DC plug off the original power supply and used a wire nut to connect the postive and negative wires.. Make sure you wire it correctly!
Then pull off the extra pairs for your data if needed.
If the switch supports PoE on one of the ethernet ports then you could obviously just plug into that port.. Otherwise you’ll have to do what I suggested above.
Yeah, it’s obvious that on the short distance it has to work, but we’re talking about 60m of wire lenght here.. I’m aware of how to connect everything (using 4-5 and 7-8 pins on RJ45 connector). I guess i’ll use small SMC 5port switch, wich only needs 4-5W of power and give a try..
What is being described above is a POE splitter. A reverse POE injector with a voltage regulator.
You can build it your self in about 20 minutes.
You can either use a POE calculator (like this http://www.gweep.net/~sfoskett/tech/poecalc.html ) to size your input voltage (requiring no regulator), or cut a 5v voltage regulator off an old motherboard.
If you do not have an old mother board, the 7805 +5VDC voltage regulator provided at RadioShack is capable of handling 1 A and can take up to 35 V input.
If it must look professional get a dual rj45 surface mount jack and put all your soldering in it, and use the little input hole in the back for you power pigtail.
Well, i thought of a voltage regulator, but then i would have to use higher voltage DC power supply (not the one provided with the switch i have got). The setup with injector on one end and splitter on the other is clear too.. I’m planning to use “on-surface” mounted single port RJ45 jack with a DC socket on one, and DC plug on other.. The only thing that bothered me was the power loss in such a long cable, but things started to get clear..
Yes, with no VR, if the switch is 5v, you will need a 7.5v power supply at 180ft. Use the POE calculator I linked to. If you use the included power supply you will only have 2.7v.
The higher the voltage, the less loss.
drop the soldering iron…it’s been done already, I’ve used the 8 port over an 80m cable:
http://www.planet.com.tw/product/product_dm.php?product_id=368&menu_id=30
http://www.planet.com.tw/product/product_dm.php?product_id=274&menu_id=30