NAS

DIY 6 port PoE Injector

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Here is how i did my PoE injector.
Injectors are expensive, cheap plastic or just one port which then dangle in the air between the cables.
I had this 12 port Cat6 patch panel lie around and modified it.

On the bottom i connected pin 4/5 and 7/8 of every second LSA connector with a cable.
I also made direct connections to the RJ45 jacks cause the traces on the circuit board are thin.

Surgical procedure on the cable:
2014-11-17 182526; PoE Injector 1.jpg

Bottom:
2014-11-17 182555; PoE Injector 2.jpg

On the top just loop through pin 1, 2, 3, 6
2014-11-17 182617; PoE Injector 3.jpg

Remember this is just for 10/100 Ethernet  
Cool stuff!

awesome work

tkaiser  
And what does happen if I connect a GBit capable device like a Banana Pi directly to this sort of PoE injector? Without a passive PoE splitter in between?

tkaiser replied at Tue Nov 18, 2014 09:54
And what does happen if I connect a GBit capable device like a Banana Pi directly to this sort of Po ...

Don't do that - you will burn your device.
Gig Ethernet uses all the wires in the cable and does not work like that.

You need to make sure that on the other end 4/5 and 7/8 are not connected to the device.
You also need to be careful that you don't connect your switch to the wrong port (the ones where  4/5 and 7/8 have power) on the injector.
You need something like this:
poe-1.jpg
ccuiie1336354349529.jpg

I also found now a cheap injector: http://www.i4wifi.eu/EU-230V-pow ... injector-panel.html
But i already had the patch panel and no use for it.

tkaiser  
Edited by tkaiser at Tue Nov 18, 2014 13:33
MrGlasspoole replied at Tue Nov 18, 2014 07:21
Don't do that - you will burn your device.
Gig Ethernet uses all the wires in the cable


Thank you for the warning!

I already knew about these cheap PoE variants (that aren't compliant to 802.3af/802.3at) using passive injectors/splitters but from my understanding (electrics noob) it's important to use higher voltages over long distances and would therefore not only need a passive PoE splitter but also a step-down converter for the voltage the target device needs?

In most customer installations the combination of cheap 802.3af compliant splitters (eg. the TL-POE10R) with a PoE switch (eg. TL-SG1008P) seemed to be the better alternative since the PoE splitters can be adjusted between 5/9/12V. And being able to use Gbit network speeds matters as well

Am I wrong with my assumption that the higher the voltage, the lesser the drops -- especially over longer distances? A former colleague told me that we should always go with 48V on the cable...

Thx for the mention of the cheap 8-port-injector anyway. Might be very useful for a home project with short distances but different rooms (and CAT5e already present)

tkaiser replied at Tue Nov 18, 2014 15:07
Thank you for the warning!

I already knew about these cheap PoE variants (that aren't compliant t ...

Yes you need higher Voltages to compensate the power lose.
But the IEEE 802.3 standard has the 100 meters (328 feet) maximum cable length of Ethernet in mind.
I don't have that kind of length - more 5, 10 max 20 meters.
I go with 24 volt cause i have allot of other stuff that works with 24 volt - so i need just one 24 volt power supply for everything.
Here is some calculator for cable length, wire gauge, power lose: http://blog.fosketts.net/toolbox/power-ethernet-calculator/

There is another one in German that also tells you if your save: http://www.bmc-braunschweig.de/i ... abeldimensionierung

For Arduinos, Cams, some routers and access point 10/100 Ethernet is enough.
Some Videos:
https://www.youtube.com/watch?v=KL9Te_hSiOA
https://www.youtube.com/watch?v=NhCATUfMA7Y

tkaiser  
Thank you very much for this useful input. Highly appreciated

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