FON Boards

I wanted to improve the range and reception quality of my wifi hotspot for my neighbors, because it wasn't very good with the router inside the house. There are basically two options for improving reception outdoors: an expensive extension antenna at the end of an *incredibly* expensive cable, or mounting the whole router in a weatherproof box and running a much cheaper ethernet cable up to it.

I did not want to run an additional wire to the router for power, so I decided to build a POE kit for it. Basically, the ethernet cable has two unused twisted pairs of wire. A pair of adapters are built which allow power to be run between them over these wires. The wires are kind of thin for this purpose, and some voltage is lost over large distances, but usually a whole twisted pair is used for each polarity (-) (+). The shorter, connecting cables that are not between the adapters should not be energised, since you don't know if your hub is supplying POE in an incompatible way, or if one or more devices is built to ground or short-circuit these terminals.

These instructions told me how to quickly and safely open the case. This will void your warranty, but remember that if you bought your router from FON, they have sold it to you *without* a warranty: http://voidmain.is-a-geek.net/redhat/wrt54g_revival.html

I was going to build a *pair* of POE adapters out of ethernet cable connectors (the kind to make one long cable out of two), but there was only one left in the store. Looking at the back of the circuit board of my Linksys WRT54GL router, I saw that the necessary terminals were left unconnected, not grounded nor shorted with other terminals. This would make it easy to simply solder a pair of wires onto the back of the router circuit board.

This diagram shows the actual choice of wiring polarity I used, and is the most used standard, "New Cisco POE":




And finally, here are the actual pictures of my own completed Frankenstein:

My soldering skills could use some improvement!

NAKED ROUTER, WOO-HOO!!! (You can barely tell, but yes, the LED lights are on)

I should have put a power receptacle on the adapter, but I was impatient so I just cut the power cord. After stripping the wires and resoldering them, I chose to reattach the plug so I can still use it directly. I marked the "energised" side with the red dot. The POE is only connected to the jack on the left leading to the router's WAN port, not the one on the right leading to my cable modem.


Here is one of the world's best tutorials on building your own POE kit:
http://www.nycwireless.net/poe/

The next stage is building a weatherproof enclosure. I'm looking for a plastic food storage container ("Tupperware") as a temporary solution.

I'm not sure this will be my permanent enclosure, because it's not as watertight as I would like, but it sure does look cool. Too cool, in fact. I think I may have to put black electrical tape over the lights because they would look too conspicuous in the clear box, in the dark, up in the tree where you can see it for a couple blocks all around.

This is a tackle box, for holding fishing supplies. It has dividers molded in the plastic. I marked the outline of the router onto the top of the dividers and then cut those walls down *halfway*, giving the router a snug fit and an "embedded in ice" look.

The only external hole in the case is on the bottom. I'll seal it on the top and sides, but leave the whole bottom unsealed just in case water does manage to drip inside, so it can quickly run out again. This will also act as pressure relief for when the air heats and cools.

I took care to give the ethernet cable gentle curves and so it goes through slots in 3 places in the divider walls. The whole thing is light enough that I feel comfortable hanging it from the ethernet cable itself, though I will need to build some kind of tension-relief for the part that drapes over the top of the tree limb. It does not really matter to me if the cable eventually breaks; it is very old and it is only CAT4 anyway. It was salvaged from a Motorola laboratory 10 years ago. It was probably state-of-the-art when installed there

We'll see how this goes. If I decide to put the router up looking like this, I will seal the edges with a glue gun, or perhaps epoxy. I am also aware that I have a very brave squirrel up there, so I hope he does not chew on it!

Nice. I think I will try to do that with my box as well.

Excellent write-up!
Thank you.

I was thinking that i'd really love to put one of those ethernet-connected webcams up there with the router, for a high-up, panoramic view of the yard. Too bad they're too expensive right now. If it runs on 12v, I might even power it off the POE too, as the standard 12v power supply that comes with the router is actually more than twice as powerful as it needs to be.

I wonder though if that power rating is assuming the default 28mW broadcast power, and how much more it does in fact use if you set it to 300mW.

Good question, but from what i've read, there is little to gain from boosting it beyond 70, which is still safe in regard to generating extra heat. If you set it to 300, you might get people to pick up your SSID from a mile away, but their poor little laptop wifi card doesn't have the same power to broadcast back to it!

I'm still "bench testing" my modified router set to 70mW, and with DC power running through an 80 foot ethernet cable. The power supply is barely warm, so I know that even after the extra resistance, the p/s is not under any strain.

Wow nice job AustinTX - mind if I put your creation on my site?

Also take a look at what FON "may" be working on. The FON Nano - again this is rumor! http://www.fonternet.com

That would be fine with me, Ross.

Stay tuned for more photos. I need to take some shots inside the injector adapter before I fill it with glue and close it permanently.

Here's an overview of the POE "injector" adapter I built. As I said above, I could have put a DC power receptical into the side, so I would not have to cut the router's power cord, but I was impatient. I reattached the DC plug though, so I can still plug it straight into the router if I am no longer using POE.



Here is a closeup of the converted ethernet cable extender. This was the best shot I could take of it, i'm sorry for the poor quality. The wires inside are not twisted-pair, which is why it is never recommended to use these. You'll never get 100Mbits across that gap, but i'm sure it will be no problem for sharing the typical 1.5 - 4Mbit internet connections (in the USA).



The left side is the "energised" side which connects to the cable leading to the router. The right side, leading to the cable/DSL modem is physically disconnected from the DC power because those 4 wires are simply cut off. I didn't bother insulating the soldered wires because I found that when I stuffed them into the corners and snapped the adapter shut, they stayed put. Ordinary POE solutions involve building TWO adapters, but my substitute for the "extractor" adapter was soldering jumpers on my router circuit board. The white-striped wire from the AC adaptor was the positive (+) side. I just used a power drill to make the hole for the DC wires.

For an even better tutorial on building your own POE kit, let me direct you again to one of the best I have seen anywhere: http://www.nycwireless.net/poe/

Good luck with your projects, and have FON!

You will probably want to take into consideration the possibility of dew/frost/high humidity, in which case there is the possibility of water condensing in the box, creating an unsave environment for the router.

To solve this you could get a bunch of those "Silica Gell" packets found in new shoes, certain food items, etc... and put them in various places in the box. This wouldn't keep all non-rain water out, but it would certainely help.

Good point, benkillin. I had an idea for making my own moisture absorbers out of coffee filters stapled shut with a few spoons full of kitty litter (mostly powdered clay) inside.

Another fear I have is what will happen when it starts to get hot outside. The router as manufactured has parts that are held in place using HOT GLUE!

I have a couple of spare 3v or 5v laptop cooling fans, and i'm thinking of ways I could use them to my advantage. One on the CPU with a heatsink might help a *little* even though the box will be closed. The surface of the box itself works as a heatsink. I might put another fan at a hole on the bottom to force an air exchange too.

Just mount a window AC unit in the tree...

BTW, if you have an old PC or dead motherboard, the heatsinks stuck to the chipset work great because they are small enough for the router, and their heat disipation capacity is greatly sufficient for the router's processor.

To get the heatsink off just use some scissors or a similar object as a lever to pry it off the chip.

I have put a nice, flattish 2" heat sink onto the router's cpu. The box i'm using is too shallow for a tall one. The heat sink gets suprisingly hot so I added a 12v fan. I'm more concerned than ever about heat now, so I have put off installing my router outside until I have devised a better cooling system that will survive the conditions. I'm probably going to build a forced-air system with tubes to guide the air across the heat sink and i'll make an effort to put the router in the shade. Too bad aluminum foil is out of the question!

http://blogs.cjb.net/fon/93377/
Here you see from the dust buildup that my fan really is doing a bit of work. I took these pictures months later, and gave the fan and heatsink a good cleaning.


This little 12v CPU fan comes from a very old computer. It's a bit smaller than the standard "small" CPU fan you see these days. I basically selected it because it was the quietest fan I had that would fit in the space. The heatsink is also much flatter than most others. I'm not sure what it came from since I have drawers full of used stuff like this.

Nice work
I have done this commercially. Some hint's without giving away the farm.
Consumer grade spec's are 0-40C, with junction temps ~ 100C. Not like that most places. Junction temps are limiting factors so R theta calcs are required.
Sun exposed walls will hit >60C. Puts junctions at 120C.
Mounting 4" off walls will reduce temp about 10C.
Beware of shaded alcoves. Heat traps!!
Sheild from rain and drain! A gortex plug works great. Drains, blocks intrusions and equalizes air pressure.
Humidity is what kills. Maintain internal temp @ 10C above ambient and you will never have the killer condensation.
Integrate a chimney on the rear wall, and bond the hot board to that wall. Natural convection will do the rest.
Paint white or gray for best emmissivity.

The hard part is how to keep the box above 0C.

I should add a couple more items, trying not to be a grinch.

Outdoor consumer electronics :ie lna/lnb recievers for sat tv have taken about 20 years to become cost effective, mainly due to issues you are looking at. Basically reciever grade mil spec -40-+70 can be cost effective in quantity. When you add transmit power and 'sloppy power consumption design' both delivery of power and removal of said power becomes a real issue.

So the high cost of cable/antenna?? for an indoor mount.

PoE not good enough for you? Try Pos! (Power over Sunlight):

http://www.green-wifi.org/projects/gw/prototype.html

As you say, there is little to be gained by increasing output power at one end of a wireless link. Improving antennas though is a very worthwhile alteration since it works both ways, improving effective output and sensitivity. If you have a particular direction you want to approach, you can build a reflector alongside your box, even going as far as attaching a 'dish' to your outdoor router. I have seen experiments of five mile wireless links done with cheap chinese cookware and cheap usb wifi sticks, using the sticks like an LNB in a satellite dish, if you can visualise that (putting the usb stick at the approximate focal point of the Chinese wok). The router as boxed in the photos is small enough to do that with.

This may seem a trifle esoteric, but might have some application to a user who wants to link in with a particular location or settlement rather further off than is normal for a FON hotspot.

Remember - in microwave coms, power used is usually very low, often a lot lower than these routers are using. Antennas are however very important and at these frequencies can add huge gains to both transmit AND receive. By putting a wifi device at the focus of 36 inch curved grid, you can add 18dbi to its transmit and receive power..... There are regulations about this which differ from country to country. Check so you don't break the rules by radiating exessive power.

Pictures here that may help - just imagine a weather proofed router at the focal point instead of a USB WIFI stick -

http://www.usbwifi.orcon.net.nz/

Is it the Broadcom CPU chip that gets hot and might need extra cooling when the TX Power is increased?

(I'm asking because the antennas themselves are fed by some other RF circuitry in a little shielding metal box some inches away from the CPU, and my first guess would be that this is the power stage where the extra heat is dissipated.)