[MLB-WIRELESS] Power over Ethernet

[Tom Parker]

Ian,

I typed a good reply but the cat ate it, so I'll try again.

You need to get an accurate picture of the current consumption using a meter
with the Eden working quite hard (if you're running linux perhaps repeated
filesystem operations of some kind would be good).  Once we know this figure
we can work from here.  I think there are a few people interested in this
board so this would be good to work out.

We also need someone to work out how much current is safe/legal over CAT5.
The Australian Wiring Handbook should give it.  I suspect it will be around
3A.  This will go down with the distance you cover.

Once we have the actual consumption then you can add a bit and put a fuse in
at that rating (provided it is less than the maximum).  Vaskos has done the
right thing putting LOW VOLTAGE AC (say 15V) over the wires and regulating
it at the masthead, the current loss will be less with AC.  You might like
to consider running some figure 8 speaker cable with your CAT5 if the
current is more than a few amps.

Do you know how good your power supply is?  Does it take 12V exactly or will
it handle more or less?  If it is flexible then it should be enough to
rectify and filter the AC and feed it into the supply.  If not then things
get complicated.

Cheers,
Tom

----------------------------------
Tom Parker tparker at netspace.net.au
http://www.wiresncode.com/projects



> -----Original Message-----
> From: owner-melbwireless at wireless.org.au
> [mailto:owner-melbwireless at wireless.org.au]On Behalf Of Ian Donaldson
> Sent: Monday, 11 November 2002 10:51 AM
> To: melbwireless at wireless.org.au
> Subject: [MLB-WIRELESS] Power over Ethernet
>
>
> Hi all,
>
> How much power can be delivered via PoE adaptors? I want to power my Eden
> (see node page) via PoE. Its in a case that takes an offboard
> power supply,
> so the input is 12V @ 5A. However the machine is fanless and diskless so
> will be pulling less than that, maybe a lot less.
>
> Anyone with an electrical clue feel like building some PoE
> adaptors for me?
> :)
>
> Ian
> --
> Ian Donaldson, SA @ MI                       -- ian at myinternet.com.au
>
>
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