[MLB-WIRELESS] Power over Ethernet

[Ian Donaldson]

Thanks for the reply Tom. Would a clamp meter be the appropriate tool for 
the job?

Repeated filesystems ops wont affect power consumption much as the box is 
diskless, but perhaps max the CPU while sending lots of packets on both 
interfaces. I certainly think it'll be less than 5A.

I don't know how good the PSU (DC-DC) on the Eden is. The best judgement I 
can make is that the offboard (AC-DC) power brick is large and heavy, so 
its probably delivering a pretty good DC signal into the Eden.

Thanks for the suggestion about figure 8 cable. That would be a lot easier 
than running 240V into the roof.

Regards,

Ian

On Tue, 12 Nov 2002 20:57, you wrote:
> 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
> >
> >
> > To unsubscribe: send mail to majordomo at wireless.org.au
> > with "unsubscribe melbwireless" in the body of the message

-- 
Ian Donaldson, SA @ MI                       -- ian at myinternet.com.au


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