DC power over ethernet.

[Jan Panteltje]

I was reading an article in the NYtimes (website you need to register),
that describes how normal ethernet cables are used to ALSO supply power
to appliances that are connected to that net.
So you can for sure send a few hundred mA over the free lines (there are
8, you only need 4) of a normal ethernet plug / cable.
Great for powering a TCP phone for example.
Has anyone here done such a thing?
Is there universal agreement about how much current / voltage
(say a standard).
There are 2 'telephone wires', so you could put 60 V DC?
JP

 

[Ian Stirling]

Jan Panteltje <pNaonSptaemltje@yahoo.com> wrote:

I was reading an article in the NYtimes (website you need to register),
that describes how normal ethernet cables are used to ALSO supply power
to appliances that are connected to that net.

Search for "power over ethernet"
Many boxes that do this.

 

[Rene Tschaggelar]

Jan Panteltje wrote:

I was reading an article in the NYtimes (website you need to register),
that describes how normal ethernet cables are used to ALSO supply power
to appliances that are connected to that net.
So you can for sure send a few hundred mA over the free lines (there are
8, you only need 4) of a normal ethernet plug / cable.
Great for powering a TCP phone for example.
Has anyone here done such a thing?
Is there universal agreement about how much current / voltage
(say a standard).
There are 2 'telephone wires', so you could put 60 V DC?
JP

While I didn't use any of this technology, I saw a few chips
recently. At linear tech. There is a legal difference between
48V and higher. Savety standards and such.
I once saw a remote submarine system where they sent a few
hundred volts over a coaxial cable together with data. That
wasn't 100MBit ethernet then.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

 

[Martin Riddle]

I think there is a article on a DIY POE on http://www.nycwireless.net/.

Cheers

"Jan Panteltje" <pNaonSptaemltje@yahoo.com> wrote in message news:c441vj$hoa$1@news.wplus.net...

I was reading an article in the NYtimes (website you need to register),
that describes how normal ethernet cables are used to ALSO supply power
to appliances that are connected to that net.
So you can for sure send a few hundred mA over the free lines (there are
8, you only need 4) of a normal ethernet plug / cable.
Great for powering a TCP phone for example.
Has anyone here done such a thing?
Is there universal agreement about how much current / voltage
(say a standard).
There are 2 'telephone wires', so you could put 60 V DC?
JP

 

[Mac]

On Sat, 27 Mar 2004 14:10:13 +0000, Jan Panteltje wrote:

I was reading an article in the NYtimes (website you need to register),
that describes how normal ethernet cables are used to ALSO supply power
to appliances that are connected to that net.
So you can for sure send a few hundred mA over the free lines (there are
8, you only need 4) of a normal ethernet plug / cable.
Great for powering a TCP phone for example.
Has anyone here done such a thing?
Is there universal agreement about how much current / voltage
(say a standard).
There are 2 'telephone wires', so you could put 60 V DC?
JP

Gigabit ethernet uses all four pairs in a cat five cable. You may still be
able to make some kind of scheme work, since the signals are transformer
coupled.

--Mac

 

[Richard]

Jan Panteltje wrote:

So you can for sure send a few hundred mA over the
free lines (there are 8, you only need 4) of a
normal ethernet plug / cable.

Yes, this has been done for years, but is only now becoming
standardized.

Power can be supplied in one of two ways under the 802.3af standard.
The primary method level-shifts the TX and RX pairs to create a 48v
potential between them. The alternate method uses the free pairs 1 and
4.

Great for powering a TCP phone for example.
Has anyone here done such a thing?
Is there universal agreement about how much current / voltage
(say a standard).
There are 2 'telephone wires', so you could put 60 V DC?

It can be that simple, but it's not recommended. Early proprietary
systems tried this and burned up more than a few Ethernet cards that
didn't leave these pins unconnected like they expected.

The new specs use power controllers on both ends of the link. The
powered device (phone) applies a "signature" resistance / capacitance
combination on the wire that causes the powering device (Ethernet
switch) to apply power to the line.

Check out http://www.elecdesign.com/Articles/Index.cfm?ArticleID=5945

Linear Technologies is a leading vendor in this area.
http://www.linear.com/pub/q_srch.html?target=ltc4257&pub_type=All

 

[Jan Panteltje]

On a sunny day (Sun, 28 Mar 2004 11:15:23 -0700) it happened Richard
<rh86@azglobal.com> wrote in <4067163B.A2C01CB9@azglobal.com>:

Jan Panteltje wrote:
So you can for sure send a few hundred mA over the
free lines (there are 8, you only need 4) of a
normal ethernet plug / cable.

Yes, this has been done for years, but is only now becoming
standardized.

Power can be supplied in one of two ways under the 802.3af standard.
The primary method level-shifts the TX and RX pairs to create a 48v
potential between them. The alternate method uses the free pairs 1 and
4.


Great for powering a TCP phone for example.
Has anyone here done such a thing?
Is there universal agreement about how much current / voltage
(say a standard).
There are 2 'telephone wires', so you could put 60 V DC?


It can be that simple, but it's not recommended. Early proprietary
systems tried this and burned up more than a few Ethernet cards that
didn't leave these pins unconnected like they expected.

The new specs use power controllers on both ends of the link. The
powered device (phone) applies a "signature" resistance / capacitance
combination on the wire that causes the powering device (Ethernet
switch) to apply power to the line.

Check out http://www.elecdesign.com/Articles/Index.cfm?ArticleID=5945
Very nice clearly written article.

Linear Technologies is a leading vendor in this area.
http://www.linear.com/pub/q_srch.html?target=ltc4257&pub_type=All
And that also answeres the question how to make the controller

Thank you (and teh others) for this high qyuality info.
I also downloaded the IEEE 802.3af-2003 spec sheets.
A lot of info!

Thank you guys!
JP