DIY PoE injector - ?12v/24v/48v

[michaelsandy]

Hi,
Am rigging up a DIY PoE injector cable, as i have lots of cable etc but don't know what voltage a 3 Mp Hikvision 2cd-2532f-IS is expecting... would it safely run on a 12v PoE input?
This is an older camera, obviously, circa 2015
It has separate 12v inputs, if not running via PoE...
Thanks
michaelsandy

 

[eggsan]

a poe connection needs all four cable pairs for data + power. If the camera feeds the +12v directly, you may use the brown (-) and blue (+) pairs for power.

 

[TonyR]

@eggsan 's is correct but I just want to add to what he said so there's no assumptions made about the cable wiring spec, pinouts, etc. since you recently joined.

First, your CAT-5 cable should be wired on BOTH ends to the T-568B spec so that the colors he mentioned are on the appropriate pins (power 4/5 + and 7/8 - and data 1/2 and 3/6). See Image 1 below.

If you're going to power that cam via 12VDC I recommend purchasing a pair of passive splitters. See Image 2 below.

This should put the data on the 2 correct pairs (WO/O & WG/G) and the power on the 2 correct pairs (Blu/WBlu and Br/WBr).

The specs say the cam draws 5 watts max. On 12VDC I'd say standard 24 gauge CAT-5e cable should be able to run to a max length of 50 feet. That's not very far. Beyond 50 feet there'd likely be too much voltage drop for reliable camera operation, especially at night when the cam's IR comes on. If you plan for the cam to be beyond 50 feet I'd consider running the cam on a 802.3af/at-complaint POE injector or POE switch and use the cam's RJ-45 for POE and data input.

Either way, insure the CAT-5e/6 cable is pure, solid (not stranded) copper and not CCA (Copper Clad Aluminum).

Image1



Image2



EDIT: Welcome to IPCT !

 

[michaelsandy]

Thanks very much to both above posters
.
Is it ok to wire together the brown/brown white and blue/blue/white...as YouTube howto's seem to propose..?

As this will be a fairly crude once only use, to update camera firmware via tftp on a wonky 192..0.0.x domain.

 

[TonyR]

Is it ok to wire together the brown/brown white and blue/blue/white...as YouTube howto's seem to propose..?

Having not seen the YT video I can't honestly say....but if you're talking putting nothing but passive POE and data on the CAT-5e and shorting 4 to 5 and shorting 7 to 8, it seems totally unnecessary since both colors in a pair (like 4/5) are already the same potential and it's DC, not AC. It's a balanced line and crosstalk in UTP should not be an issue either. But, again, I haven't seen the video and thought your plan in the OP was to power a 12VDC camera with 2 pair of a CAT-5e cable.

 

[michaelsandy]

thanks
Its because I don't know if the camera draws from 4 or 5, and 7 or 8
Hence thinking they should be shorted..?

 

[TonyR]

thanks
Its because I don't know if the camera draws from 4 or 5, and 7 or 8
Hence thinking they should be shorted..?

As stated earlier, in 802.3af/at POE both 4 & 5 (Blue & Blue/W) carry DC+ and both 7 & 8 (Brn & Brn/W) carry DC - so you likely do NOT need to short them in your application...I cannot say for sure because, again, I have not seen the video and have no idea what the author's intent is.

 

[michaelsandy]

Thanks again for helping!

 

[Mark_M]

What is mentioned above about a passive POE injector/splitter is the easiest and probably safest way to do it.

Ramble time... a very quick rundown of an actual POE injector/switch:

POE 802.af/at uses around 48V DC, this is to combat voltage drop over the cable and because a higher voltage means the current can be lower for the same wattage. Issues with making a DIY 802.af/at compliant injector is the logic behind it figuring out if the device actually supports POE. If you plug your computer into a POE injector, that injector can identify right away that the connected device is not capable of POE. This is done by measuring resistance between certain pins on the devices RJ45 connector ('network connector'). If there is the 'resistance' between the certain pins, the POE injector will power on for a fraction of a second. In this time, it is wanting a response back from the device to verify that it is being powered. If the device fails to respond, the POE injector shuts off to hopefully prevent damage (in case the device actually didn't support POE). All this is done to (help) prevent the possibility of a device being sent 48V DC and causing damage.

What I gather you are finding online is making a passive POE injector/splitter system. That is fine and perfectly valid for a DIY project.

 

[michaelsandy]

Thanks for the reassurance.
On further consideration, is the redundant wiring ie blue/blue white, brown/brown white, in any way relevant to the supply of the different PoE voltages?

 

[TonyR]

On further consideration, is the redundant wiring ie blue/blue white, brown/brown white, in any way relevant to the supply of the different PoE voltages?

Not to my knowledge but I'm no means a POE guru.
If you have some time, want to know more than you do now about POE or can't fall asleep some night, go for it ==>> Power Over Ethernet Wikipedia

 

[CamFan]

Thanks for the reassurance.
On further consideration, is the redundant wiring ie blue/blue white, brown/brown white, in any way relevant to the supply of the different PoE voltages?

Power over Ethernet - Wikipedia

en.wikipedia.org

You can feed your DC + and - per this diagram, DC on the spares. Voltage, 48V max, shouldn't hurt to try it at 12 or 24. For short runs, you can just feed it down 2 wires (12V on blue, 0V on brown). Use both colors in the pair for long runs, this is to reduce the voltage drop.

Just stay away from the data lines, and bobs your uncle .

 

[tangent]

Honestly, just buy a cheap 802.3af or 802.3at PoE switch or injector.

 

[TonyR]

You can feed your DC + and - per this diagram, DC on the spares. Voltage, 48V max, shouldn't hurt to try it at 12 or 24. For short runs, you can just feed it down 2 wires (12V on blue, 0V on brown). Use both colors in the pair for long runs, this is to reduce the voltage drop.

Am rigging up a DIY PoE injector cable, as i have lots of cable etc but don't know what voltage a 3 Mp Hikvision 2cd-2532f-IS is expecting... would it safely run on a 12v PoE input?
This is an older camera, obviously, circa 2015
It has separate 12v inputs, if not running via PoE...

@michaelsandy .....
Jeez, if I lived close by you I'd give you a pair of the splitters and I'd even give you a 12VDC wall wart too if you didn't have one...

Those splitters are cheap ($8 for 2 sets!) and purpose built to do what you need. I'm all about learning (we learn best by doing) but you've done enough research now to have learned how it works and what to do but......at this point, if it were me, I'd drop a few bucks on ether a pair of splitters as I mentioned in post #3 or, if the cam is 802.3af/af POE-compliant, a POE injector or POE switch also mentioned in my post #3 and again by @tangent above and put that cam to work !

 

[tangent]

Camera is 802.3af

Ubiquity 802.3af Supported POE Injector, White, 48V, 36W: Network Switches: Amazon.com.au

Ubiquity 802.3af Supported POE Injector, White, 48V, 36W: Network Switches: Amazon.com.au

www.amazon.com.au

https://www.amazon.com.au/TP-Link-TL-POE150S-PoE-Injector-Adapter/dp/B001PS9E5I/

TP-Link 8-Port 10/100Mbps Desktop Switch with 4-Port PoE - @41W, 250m range, priority mode, 802.3af, plug and play (TL-SF1008LP) | AU Version |: Network Switches: Amazon.com.au

TP-Link 8-Port 10/100Mbps Desktop Switch with 4-Port PoE - @41W, 250m range, priority mode, 802.3af, plug and play (TL-SF1008LP) | AU Version |: Network Switches: Amazon.com.au

www.amazon.com.au

https://www.amazon.com.au/TP-Link-9-Port-100Mbps-Desktop-Switch/dp/B08GDC8X1Y/

 

[michaelsandy]

Hi again
No luck with the 12v
They must be expecting 48v, which is the voltage of matching hikvision PoE NVR..? showing a picture of my DIY cable arrangement...

 

[Mark_M]

Hi again
No luck with the 12v
They must be expecting 48v, which is the voltage of matching hikvision PoE NVR..? showing a picture of my DIY cable arrangement...

Oh, so you are trying to use the POE power input inside the camera?
That won't work unless it's a POE compliant injector.... It wants more than 40v DC.

If you want passive POE at 12v, then a pair of those adaptors (like already mentioned) will do it. But that uses the 12v DC barrel jack on the camera to power it.

 

[michaelsandy]

The 48 v power supply runs the NVR, through which the cameras connect.
But the NVR has old firmware and upgrading that is part 2
Part 1 being the Cameras

 

[Mark_M]

The 48 v power supply runs the NVR, through which the cameras connect.

Usually when the NVR itself runs on a 48v DC power supply, it means the ethernet ports at the back support POE to the cameras (powering the cameras up).

But the NVR has old firmware and upgrading that is part 2
Part 1 being the Cameras

What is this about doing tasks in parts...?
Regardless of what software is on an NVR, POE should be avaliable out the back for cameras.

---

At this point, just seriously buy a POE injector.
They hardly cost anything, even at NZ prices.

 

[TonyR]

Hi again
No luck with the 12v
They must be expecting 48v, which is the voltage of matching hikvision PoE NVR..? showing a picture of my DIY cable arrangement...

Jeez, man...I don't know what else to say....

Even before @Mark_M provided the nice schematic I sent you this in my FIRST post, stating "...If you're going to power that cam via 12VDC I recommend purchasing a pair of passive splitters" and provided a picture!

As shown in his schematic, the left red box is the camera end...the male coaxial power plug plugs into the matching female 12VDC connector on the camera; the RJ-45 male plugs into the cam's female RJ-45 for data. Your CAT-5e/6 cable's male RJ-45 plugs into the RJ-45 female on the splitter.

The right red box is the power supply end.....your 12VDC power supply male plugs into into the matching female connector, the RJ-45 male plugs into the switch or NVR female RJ-45 for data. Your CAT-5e/6 cable's male RJ-45 plugs into the RJ-45 female on the splitter.

The power connectors on the camera, the splitter and the 12VDC power supply are all polarized so you can't hook it up wrong if you wanted to!