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Power over Ethernet (PoE) basics and beyond

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257 points voxadam | 2 comments | 16 Oct 25 14:09 UTC | HN request time: 0.466s | source
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skopje ◴[22 Oct 25 00:53 UTC] No.45663732[source]▶
PoE is awesome. My custom home security system is all CCTV PoE with a gstreamer backend running on four-core fanless linux box. Way to go. Complete control. No batteries, no wares spying on me, no personal data getting scraped by big guys. (Cloud connectivity sucks because I have segmented mp4s and jogging through them hurts but I only care for events after they happen, not while they happen.)
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dheera ◴[22 Oct 25 05:11 UTC] No.45665099[source]▶
Except when it isn't awesome. There are multiple PoE standards. Passive PoE, active PoE, PoE+, PoE++, PoE+++, 802.11af, 802.11at, 802.foo, blah blah.

If they had just stuck with 12VDC and buildings had 12VDC wall sockets everywhere, everything would have been fantastic.

I also had a PoE HAT for a RPi that smoked it. Never doing PoE again. 48V and 3.3V electronics probably don't belong within 10cm of each other.

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1. ssl-3 ◴[22 Oct 25 06:23 UTC] No.45665484[source]▶
> If they had just stuck with 12VDC and buildings had 12VDC wall sockets everywhere, everything would have been fantastic.

Huh? We used to have low-voltage AC and DC powered cameras in the world (and we still do, too).

Those are awful in implementation because buildings, whether or old or new, don't have 12VDC sockets everywhere -- or at all, really.

Nor should they have 12VDC sockets for cameras; they're unnecessary.

I've run my share of siamese coax for low-voltage-fed analog cameras, and also separate power for low-voltage Ethernet-connected cameras, and I'm completely over those concepts.

With proper-fucking IEEE POE, we have standards and it only takes one cable to make it work properly instead of more than one.

If a switch isn't up to the power demands of a particular camera, then: No big deal. I can upgrade or supplement that switch without rewiring even more of the building than was already necessary to get Ethernet going.

(Structured cabling for the win.

Passive POE: Not even once.)

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2. eqvinox ◴[22 Oct 25 06:28 UTC] No.45665524[source]▶
> Passive POE: Not even once.

Amen.