Faux POE for home networked cameras

Discussion in 'The Projects Forum' started by pfurrie, Feb 16, 2012.

  1. pfurrie

    Thread Starter New Member

    Feb 16, 2012
    Short story version: I'm trying to figure out a good way to inject and split power over ethernet for several different brands of networked cameras.

    Long version:
    I ran ethernet throughout the house for various devices, including about a dozen for network cameras. The intent is to power all the cameras over the network line, using the two unused pairs in the bundle. None of the cameras have native POE capability... what I need to do is inject the power in my home wiring closet, and then split out the power just before the camera.

    Wiring the injecting and splitting isn't a problem -- managed that. The problem is that I'm not getting enough juice at the camera to make it go. I can get the network link lights to fire up, but it seems that when the camera (different brands and models) reach different points in their boot, they re-cycle. I suspect something is drawing more current at that point, dropping the voltage below some theshold needed for the camera, so it reboots. Lather, rinse, repeat.

    Yep, have tried goosing the voltage at the source end. Still no joy. Not sure how far I can push things before I fry something. In addition, it isn't a very elegant solution, guessing at the voltage I need in that manner.

    Initially, I tried building a master power supply connected to an 12-port injector block I'd wired up. Each port had a voltage regulator and an adjustor pot, so I could dial in each camera individually. However, I don't think I was getting the current I needed at the other end.

    I would still like to have one master power supply, but now having to re-think how this works, but I'm easily out of my depth here (in what seems like shallow waters). The camera voltages are from 5 to 12 volts, depending on the make/model (I have Sony, Panasonic, and two other brands I can't think of right now). Some have pan and tilt, so require a bit more oomph, and some have IR illumination, too.

    On all the injector/splitter setups, I'm using one pair for positive, one pair for negative (in both cases I'm using both wires). And the voltages I'm using are running up to a little more than 12 volts.

    I've been looking online for months, and find a few DIY faux "POE" setups, but some are for single-device use, or don't give enough info which would help in this case.


    1. Would there be any advantages to using a much higher source voltage (48v?), and trimming/regulating it at the splitter end instead?
    2. What other questions should I be asking?
    3. Other thoughts?
    I know... some people might ask "why not power at the device, and go wireless for networking?" The philosophy here is to reserve wireless for mobile devices. Anything which has a fixed location gets a wired connection. With 12 cameras, that is just too much wasted wireless bandwidth. Plus, having to run A/C power to each location is a non-starter.
  2. BSomer


    Dec 28, 2011
    You may be having an issue with voltage drop. Have you tried to measure the voltage at the camera while it is connected? I presume you are using a CAT5 cable or similar, in which case the 24AWG wire is kind of small to power anything that draws a lot of current over any substantial distance.
  3. ifixit

    Well-Known Member

    Nov 20, 2008
    Hi pfurrie,

    I'm going to assume you are suppling DC power through the twisted pair.

    Try adding 100uF capacitor at the camera end. This acts like a power reservoir, or battery, that can supply extra surge power for a brief time such as during boot up, or pan & tilt operations. The long 24 gauge wire is likely not able to keep the voltage up above minimum when the current peaks.

    I'm not sure of the capacitance value that is required since you have not given voltage/current details for each camera. So try 100uF first and then move up in value until it works.

  4. John P

    AAC Fanatic!

    Oct 14, 2008
    It's a hassle, but maybe you need to have independent step-down switching voltage regulators at each point, operating off some relatively high input voltage, maybe 24 or something like that. By doing this, you get efficient use of the power line (high voltage, low current) and the capacitors associated with the regulators can handle surges.