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Power over Ethernet (PoE) basics and beyond

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257 points voxadam | 1 comments | 16 Oct 25 14:09 UTC | HN request time: 0.203s | 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. varenc ◴[22 Oct 25 05:22 UTC] No.45665150[source]▶
I use a PoE "extractor" to power my RPi over PoE and it works great. The extractor does the negotiation and safely gets the normal 48V PoE power, then converts that to 5V outputted on a USB-C cable that powers the RPi. Extractor also has an Ethernet[1] passthrough port that goes into the RPi as well. A bit basic, but seems relatively error proof.

[1] https://x.com/varenc/status/1961587127931867466