Beginner question - POE 12V, 24V, 48V

[TonyR]

There's a diode on that input to help protect against reverse polarity damage that some IPCT members have bypassed (jumpered) in order to get some low amp 12VDC from the POE-powered camera.

I'll see if I can find the post.

EDIT: Here's one from @tigerwillow1 :

Powering illuminator off of POE camera?

Is there a way to piggy back off an ipcamera's (loryta/ipc 5542tm) POE power to power a 12v IR illuminator? Seems like most splitters take POE IN and then 12v dc out and non-poe ethernet out. If not how is everyone powering them? All I can come up with is an 12v power supply and a lot of...

ipcamtalk.com

 

[jnissen]

Makes sense on the diode. Yes please forward as it would potentially allow me to reduce the complexity of the external wiring at the camera.

 

[TonyR]

Makes sense on the diode. Yes please forward as it would potentially allow me to reduce the complexity of the external wiring at the camera.

See my edit above.

 

[Teken]

Just wanted to add some comments and offer insight as to the why?!? Almost every installation I’ve done in ancient history has included a dedicated 12 / 24 VDC power cable.

The AWG was obviously dictated by the cable run, required current, and meeting the 80% power limit.

Why?

Because there won’t be a need to do something dumb like opening up a camera to screw around with internal components just to get 12 VDC!

This also avoids having to buy, use, worry about another point of failure using a POE Splitter!

These solutions exist solely as a band aid to compensate for poor planning and future proofing.

If running power wire isn’t possible (highly unlikely) then using a POE Splitter with a Y cable makes sense for Joe Average.

Lastly, as it relates to any POE Switch that may be considered - Do the math! It doesn’t matter what brand it is because math is math.

You’ll see on this forum and many more about someone buying longdickdong brand A vs B.

The idiot advertisement will say POE+ on all 16 ports. But the PSU internal / external is only 150 - 300 watts?!?

What’s the math?!?

16 Ports X 30 POE+ = 480 watts!

It only gets more ridiculous when said POE+ switch is a 24 port variant!

 

[guykuo]

In stock configuration, the 12 DC jack does not output 12 volts when you connect ethernet to POE supply. Some of use modify the camera and bypass the blocking diode to convert that DC input into an output. Such a mod has even been used to power an external IR light, but obviously the modification is going to void warranty. I do it exactly for what you ask, powering external microphones.

 

[TonyR]

Just wanted to add some comments and offer insight as to the why?!?

Because they can!

 

[Teken]

Because they can!

LOL - True Enough . . .

 

[tigerwillow1]

Because there won’t be a need to do something dumb like opening up a camera to screw around with internal components just to get 12 VDC!

I take issue with this as a blanket statement. For some people, doing brain surgery isn't dumb. For me it would be . For me opening the cameras and screwing around with the components was a calculated risk that has turned out beautifully. Definitely not to be blanket-recommended, but it's not dumb for everybody. Those 12 volt wires can have pretty significant I2R losses compared to running the power over ~48 volts.

 

[jnissen]

Initial idea was to power a 12V siren off an alarm but only have POE in the area. I have a camera in the spot but not a power outlet. May mod the camera as that seems like a clean fix. If the blocking diode is ultra small or difficult I may reassess my plan.

 

[tigerwillow1]

You need to consider how much power the siren needs. With the models of cameras I pull 12 volts from, the practical limit is to pull about 4 watts, and less if you use the camera's IR lights. I turn the camera IR off, then power a 4-watt external illuminator from the camera's 12 volt supply. Here's a picture of the diode bridged in an older fixed-focus 5442. The parts seem to get a bit smaller in every new generation of cameras.

 

[jnissen]

Thanks. I've got an Annke camera I will have to see what it looks like. Very cognizant of the power requirements so I will try to keep the siren under 4W. May need to use a backup plan if I want something very loud though.