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I have the following setup, Video Intercom powered by POE. I need to power my magnetic lock with 12V.

I have a "solution" but don't really want to use it which is Split the cable since POE and 100Mbit use 2 pairs out of 4. And then I could use one of the remaining pairs to provide power to the magnetic lock.

I've been searching for a POE splitter that would provide power on both outputs. On the RJ45 to for data and power for the intercom, and just power for the magnetic lock. So far I have not been able to find a poe adapter/splitter that would do this. The reason I'm looking at an adapter is the installation would be cleaner and more organized avoiding the installation of added devices (power adapter for the magnetic lock).

As someone came across an adapter that provides power output in both RJ45 and DC Jack ?

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  • POE negotiates the voltage transmitted over the wire, so putting 2 devices on the same wire requires that the splitter is an active device is capable of changing the voltage on at least one part Commented Jan 30, 2023 at 14:48
  • Does the intercom use PoE power directly? Commented Jan 31, 2023 at 5:19
  • @ratchetfreak, I see thanks. Commented Jan 31, 2023 at 15:25
  • @ThreePhaseEel, exactly. Right now the videointercom is powered by POE. Commented Jan 31, 2023 at 15:25

2 Answers 2

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Can the video intercom be powered by DC voltage on a separate cable as an alternative to PoE? Is there a DC supply voltage that both the lock and the video intercom will accept? (12v is likely.)

Get a passive PoE injector and PoE splitter. Rather than 802.3af/at standard negotiated PoE, this kind puts the DC voltage on the wires without any active negotiation. At the load end you can then wire the DC output to both devices and pass the Ethernet signals through to the video intercom. (photo credit: ebay seller restsale89)

PoE injector/splitter set

If you prefer 802.3af/at PoE, perhaps so that the devices can be powered by an existing PoE switch which happens to give you remote power-cycle capability, then consider an active PoE splitter. It costs more than the passive kind, but this type will negotiate with the Ethernet switch and will step the nominal 48 V down to your choice of voltage (5v, 12v, etc).

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  • I ended up with going with this approach since it was the cheaper option. The suggested approach from @jay613 would end up a bit more expensive. Commented Feb 13, 2023 at 12:31
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You need two widgets:

  1. A PoE extender/repeater. You can get a 1-to-2 port device. This will allow connection of two PoE devices to one PoE cable.
  2. A PoE splitter for the lock. This allows use of PoE as a dumb DC power source. Normally the PoE device negotiates voltage. The splitter requires you to set the voltage manually, and provides separate ethernet and DC power cables.

It's a bit of a hack, it may not work. The repeater may have a DC power input plug. IF the PoE source is capable of powering the repeater, splitter, and both of your devices you may not need to provide external power to the repeater. You'll need to test it and may need to babysit it over time.

It may be easier and more reliable to power the lock separately, from a nearby AC outlet with a wall wart.

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