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Power-over-Ethernet: IEEE 802.3af Draft
SkewlD00d writes "Want power (~10W) and your fat 10/100Mbps pipe (1Gbps maybe) on the SAME jack. Surf the web and recharge your handheld w/o finding its clunky base/transformer, home automation, and control systems are just some of the possibilities. Using suitable hubs/switches or dongle, power can be provided over unused pairs, or possibly raise the signal offset above DC, X10-style (no link, u know why). See IEEE 802.3af DTE Power via MDI Task Force. Maxim (not that one :o) already has some goodies. They have schematics for 8.25W/12.5W single-output and 14.2W triple-output 802.3af PSU. Try FindChips if you're looking for them; they're in production and are NOT vapor-ware!"
The latest firewire standard can do 800Mb and provide up to 45W of power
I use this extensively with my Lucent/Orinoco wireless APs. Been doing it for about 2 years now. It's also part of 3Com's Ethernet switch/jack technology, and has been implemented for VoIP.
I've found it to be a godsend for my wireless APs, as I can mount my APs near the ceiling (away from students), and not have to worry about finding an outlet, or having them unplugged by the cleaning crew!
- why no links on X10 ?
Because they are misinformed. They are thinking of X10-the-company, which is notorious for pop-under ads. But what they really mean is X10-the-protocol [scroll down a bit for a good introduction], which is used by many companies.
- which maxim is obvious ?
Maxim is a "gentleman's magazine" that has been pushing the limits of how much semi-porn you can include without getting banned from shelves. Recently this and competing magazines went too far for Walmart.
bp
The Linear typical app seems to be much smaller, with fewer external components because it's actually optimized for the application.
The Maxim chips appear to be generic hot-swap IC's not optimized for power-over-ethernet. Using slashdot is an interesting way to publish an app-note and get some publicity.
Have you tried plugging an RJ45 in backwards (or sideways, or shifted one row to the left, or...)?
It is essentially impossible, approaching non-issue status. And nevermind that ethernet is specified to withstand multi-kilovolt fuckups between random pins, unlike massively-parallel/easy-to-crossconnect SCSI - ethernet devices don't mind seeing voltage potential where it doesn't belong.
Here's a larger problem that standardized POE solves:
User has two cables running to desktop IP phone. User unplugs cables to re-arrange desk, and upon plugging things back in, their IP phone smells funny and their external modem won't work.
Upon investigation, it turns out that the 12VAC power supply for their Sportster is not interchangable with the 13.6VDC PSU for their IP-600 phone.
Therein lies the problem with multiple incompatible, anonymous-looking power supplies at the desktop.
(In other news: Licking light sockets can be hazardous to your health. Also, this just in: Consuming too much water may cause accidental drowning.)
Kid-proof tablet..