Re: Max current at 12V DC on CAT5

[ian.bird@xxxxxxxxxxxxxxxxxxxxxxx]

You could also look at some of the POE injectors and taps as they can be
quite cheap. Be aware that the ones that conform to the standard 802.3af
will only supply power when a compliant device is attached to the end. Just
simply plugging in something that needs power won't work. An example of
this can be seen here

http://www.costcentral.com/proddetail/SonicWALL_PoE_Injector/01SSC5531/D85216/

and one that does not specify this switching and is closer to home can be
seen at

http://www.solwise.co.uk/wireless-poe-injector.htm
http://www.solwise.co.uk/networking-copper-based-poe.htm

Of course there is always the DIY route
http://www.eidusa.com/Electronics_Kits_PoE_injector.htm

They all should use -48v and can supply 1 amp at 12 volts. 2.5 amps at 5
volts etc. Read the specs and phone the company if in doubt. Most don't
seem to quote the negative voltage but this is all relative anyway. Most
also don't quote the auto sense part of the POE standard so plugging in a
non POE device may result in sparks if the cores are connected internally.

I am looking into this at the moment as I am trying to build a 'proper' POE
end device complete with the signature resistor which would make the
Sonicwall device supply power. From what I can see if it works with the
sonicwall it will work with any of the advertised poe injectors.

Enjoy

Ian





Mark Kaye
<mark.kaye@contol        To:       ukha_d@xxxxxxx
ogy.com>                 cc:       (bcc: Ian Bird/CV/Novartis)
Subject:  Re: [ukha_d] Max current at 12V DC on CAT5
04/02/2005 11:50
Please respond to
ukha_d







Mark Kaye wrote:
> Sorry, I'm a complete novice (or should that be danger) at this stuff
:)

Who should've googled this first.  I found this, quite handy:

http://www.gweep.net/~sfoskett/tech/poecalc.html