simple:
figure the total resistance roundtrip. that is... take the length
of 300ft. and double it. = 600 ft. ( assumes you are using 1-pair
of the CAT-5 line to power the radio. )
the resistance of 600ft. of 24 AWG wire = 23.3 x length/1000
= 23.3 x 600/1000
= 13.98 ohms
now figure out the Current Draw in Amps (I) of the device that will
be powered up. If its a WLAN radio, then figure about 1 Amp current
the Voltage drop (Vd) will be: Vd = I * R
Vd = 1 * 13.98
if you started with 24 Volts (Vin) then: Vout = Vin - Vd
.: Vout = 24 - 13.98
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> Today's Topics:
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> 1. RE: Power over Ethernet question (David Rhodes)
> 2. Re: Power over Ethernet question (Joel Jaeggli)
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> Message: 1
> From: "David Rhodes" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Subject: RE: [BAWUG] Power over Ethernet question
> Date: Wed, 15 Jan 2003 19:52:38 -0000
>
> http://www.nycwireless.net/poe/
>
> Check out the 'Power' section..
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Nathan Spidle
> Sent: 15 January 2003 19:39
> To: [EMAIL PROTECTED]
> Subject: [BAWUG] Power over Ethernet question
>
>
> I was looking into Power over ethernet applications and I was wondering what
> the attenuation of voltage is over Cat-5 cable per ft. Is it neglegable? or
> do you have to account for a voltage drop after x feet.
>
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> Message: 2
> Date: Wed, 15 Jan 2003 11:59:01 -0800 (PST)
> From: Joel Jaeggli <[EMAIL PROTECTED]>
> To: Nathan Spidle <[EMAIL PROTECTED]>
> cc: [EMAIL PROTECTED]
> Subject: Re: [BAWUG] Power over Ethernet question
>
> 24awg - .0302 ohms / ft.
>
> joelja
>
> On Wed, 15 Jan 2003, Nathan Spidle wrote:
>
> > I was looking into Power over ethernet applications and I was wondering
> what
> > the attenuation of voltage is over Cat-5 cable per ft. Is it neglegable?
> or
> > do you have to account for a voltage drop after x feet.
> >
> > _________________________________________________________________
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> In Dr. Johnson's famous dictionary patriotism is defined as the last
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> End of wireless Digest
=====
Dan Kramarsky
RF Engineer
SpeedBand, Inc.
=- Wireless Internet Service Provider -=
phone: 909-551-7358
web: www.speedband.com
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