12 Port Passive Power Over Ethernet Mod

Technology gets old, it gets depreciated, upgraded and discarded.

So what happens when someone picks up an old Dual Speed 100mbit HUB during a network upgrade?

They turn it into an epic POE injector of course!

This is what the unit looks like normally, my goal was to keep it looking as stock as possible.

I opened it up to find a lot of circuit board and not much else :)

I then ripped the guts out to work out just how much space there would be and to see what I could do with the circuit board.

As I said, my goal was to keep the exterior looking as stock as possible, so I grabbed the dremel and removed all the excess circuitry I could and remounted the remaining parts.

I then also popped the power supply open and discarded the excess circuitry that was not needed.
(This will be used later so I can retain the IEC socket on the back of the HUB)

Now for the fun part!

As this is a 24 port HUB, my design was to be that two ports vertically would be grouped, such that the bottom port would provide POE while the top port would be the data pass through to a switch.
This would then produce a 12 port Passive POE injector. However to get to this stage, each top and bottom row must be soldered together to pass the data through!

A lot of tedious soldering went into the next part, but once tested it proved it was all working 100%.

First one complete, only 11 more to go!

First third complete..

Two thirds completed, also showing the data pass through testing.

All complete, 24 ports turned into 12 data pass through ports. Right now its just 12 pairs of fancy cable joiners :)

Once the data pass through soldering was complete, the next step was to find a position for the new 24V 120Watt power supply which would be supplying the power to the ethernet ports.

I settled on a diagonal positioning, as I still had to fit the new circuitry in next to it..

I cut up an old IEC cable for the mains power wiring to ensure it was a high enough rating.

Once that was in place and tested by plugging the power into the rear IEC socket, it was onto soldering on the power component of the ethernet sockets.

You'll notice I continued to use actual twisted pair wiring, this not only helped with the colour coding later, it looked good too ;)

Now that the ethernet sockets are all ready, its time to position the new circuitry which will be the interconnect for all this wiring!

And the overall view at this point

Now its time to solder some more!

The new circuitry was not very complex, but enabled things to be easily removed later.

First the screw terminals were soldered on, and two main power wires were also soldered for the main connections to the powersupply.

I then put in another special screw terminal with 2 510ohm resistors in series, this was so that I could run a special cable to the front panel LEDs as I wanted the front to light up somewhat when the unit was powered on.

What did I light up you ask? Well I was originally hoping to make each port light up when a cable was plugged in, however due to the complexity of variable load there was no simple way to do this. So in the end I just opted for the simple Power light and a digit on the multi segment led :)
(There are future plans to potentially utilize the other LEDs in a chaser or something, but considering its location it would be fairly pointless ;) )

It was then time to begin wiring up the ethernet ports to the screw terminals.

Starting with brown..

Then blue, some cable ties and a final check on the voltage on the powersupply.
(Note, the power supply is variable from 20.8v all the way up to 28.0v, 20.8v was selected as the wireless devices take anything from 8v up)

A final look at the wiring into the power supply..

And a little more cable tidying..

And its finished!

So here is the final internal and external layouts!

The only thing left to do, is put it into service!

Here is its final resting place, in my roof.

The stack you see is a Mikrotik RB600A on top, TP-Link TL-SG1016D 16 Port gigabit switch and on bottom my new POE Injector!

(Note: You may be wondering why the RB600A is powered via the DC jack instead of via POE like all other wireless devices. This is because the RB600A accepts a minimum of 36v via the POE socket, however it accepts 8-28v via the DC jack. Thus I just threw a cable together to plug it into a spare POE port.. as it's not like I'll need all 12!)

So thanks for checking it out, it was a lot of fun and has made my future Air-Stream expansions here at home a lot easier with the ability to simply just run a single ethernet cable and its done!