Do It Yourself : PoE — Power over Ethernet

How-To power over your ethernet cable to an access point

by Terry Schmidt (http://www.nycwireless.net/projects/poe-power-over-ethernet).

A number of Access Point manufacturers (Lucent, Symbol) are now offering Power over Ethernet add-on’s for their Access Points. A PoE module inserts DC voltage into the unused wires in a standard ethernet cable (pairs 7-8 and 4-5). The idea is to supply the AP’s power and

UTP ethernet connectivity requirements via a single ethernet cable. This works great in areas where you may not have power and/or ethernet easily acces

sible, like a roof. This also allows you to more easily place the AP closer

to the antenna, thus reducing signal loss over antenna cabling. Ethernet signal travels well over CAT 5 cable; 2.4ghz signal doesn’t do as well over antenna cabling. Also ethernet cabling is much cheaper than antenna (LMR-400) cabling. There are currently two types of PoE adapters: a module jack or hub-like device for multiple access points. The following hack creates a simple PoE module pair.

Supplies

Parts	$	Tools
2 Port Wall Mount Module	$11	Multi-meter
1 Port Wall Mount Module	$8	Wire Cutters or Scissors
DC Male Plug	$3	Electrical Tape
DC Female Plug	$1.50	110 Punch Tool (Nice but not required)
RJ45 Crimpable Plug	0.50	RJ45 Crimping Tool
Short Ethernet Cable Scrap	$0	Soldering Iron, Solder
Total	$24

The 12 volt Apple Airport and the UGate 3300 use a 2.5mm Inner Diameter and 5.5mm Outer Diameter Coax DC Power Jacks. Other Access Points may use different sizes. (Original Linksys WAP11 (5 Volt, 2 Amp) uses 2.1mm Inner Diameter, New Linksys WAP11 uses a 5.5mm Outer Diameter and 2.5mm Inner Diameter) By using less expensive Wall Mount Modules (not CAT5 spec), or not using them at all, you can reduce the parts cost of this project. :)

Step by Step

1. Solder wires to the DC Male Power Plug. Solder one pair (2 wires twisted together) to the inner contact connection. This will be the positive power wires. Solder another pair to the outer-contact connection. Notice that on this DC Male Power Plug there are 3 connectors. One is for the center pin, one is for the outer surface, and one goes to the plug housing. You do not need to solder anything to the plug housing connector. This is what it should look liked when finished.

   

2. Drill a hole in your two-port mount housing. Mount the Male DC plug in the housing.
   
3. Connect the wires in your 2 port jack as follows (also refer to Diagram at bottom of page) (Note: this is the Intel, Symbol, Orinoco Standard, not the Cisco standard for wiring).

   

   Input Jack		Output Jack		DC Plug
   Pin 1	<->	Pin 1
   Pin 2	<->	Pin 2
   Pin 3	<->	Pin 3
   		Pin 4	<->	DC Positive Wire 1
   		Pin 5	<->	DC Positive Wire 2
   Pin 6	<->	Pin 6
   		Pin 7	<->	DC Negative Wire 1
   		Pin 8	<->	DC Negative Wire 2

4. Wire the one port wall mount jack as follows:

   

5. Input Jack		Output Jack		DC Plug
   Pin 1	<->	Pin 1
   Pin 2	<->	Pin 2
   Pin 3	<->	Pin 3
   		Pin 4	<->	DC Positive Wire 1 -> Center Connector
   		Pin 5	<->	DC Positive Wire 2 -> Center Connector
   Pin 6	<->	Pin 6
   		Pin 7	<->	DC Negative Wire 1 -> Outer Connector
   		Pin 8	<->	DC Negative Wire 2 -> Outer Connector