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The Wireless Backpack Repeater
Andy Laurence writes "So, you've decided to do a webcast around the streets of Bristol, but your puny wireless NIC isn't up to it? You need the ultimate wireless repeater! Built from an old backpack, a lead acid battery, a Linksys wireless device, and a rather scary antenna, this wireless repeater will get you webcasting from over a mile away." You'd definitely burn extra calories hiking with that thing.
8 Bannerman Buildings,
Bannerman Road,
Easton
Bristol
BS5 0RR
Telephone
0117 9025247
Hmmm.
I thought of Bristol, Connecticut, the home of ESPN. Had to look it up, and apparently it's in England.
The Linksys box probably gets 12VDC from its AC power adapter... So I doubt there's a whole lot in the way of electronics involved except for something to limit the current flow and thus not fry the thing.. And all you need for that is the right resistor.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
Well, according to the manual for the router it takes 12VDC and the connector is + Tip, that is the positive wire goes to the inside part of the plug. So no special electronics, just wire from the battery to the router. The manual also says that the router draws 1.0amp, so I'd put a 1.5 - 2 amp fuse in line as well. The router probably has an internal fuse, but for an extra $0.50 why not?
Why not go Sealed Lead Acid or, if you want to save some weight nicads/nimh?
I disagree with what you say, but I'll defend your right to say it to the death - Voltaire
Looks like the guy in the article is using a sealed lead-acid cell. These are no more likely to leak than a standard NiMH cell, and NiMH usually uses a potassium hydroxide electrolyte which is somewhat more dangerous to get on your skin.
This is a myth. From the The Straight Dope:
'SBEMAIL!' is better than a goat!!
It's not unsafe, it's a gel cell. They can run upside down or any other position for years and will not leak. The only potential problem is that if you short it out it'll get damn hot, but any decent battery will do that.
Try it with Lithium Ion (from a safe distance) - they will explode when shorted. By comparison, lead-acid gel cells are tame.
Unfortunately, pissing off the right person can land you with a very large fine. In the US, the FCC has rules on this stuff, because WiFi devices fall under Part 15.
Omnidirectional antennae (if built to the letter of the law) can only have a limited amount of gain (dependant upon the power output of the radio itself, as it's measured using dBi), where directionals can have more gain because of the limited directional scope.
At any rate, doing the math when building an antenna is essential, because the government doesn't find ignorance of the law to be a sufficient excuse. Want more info? Here's a link.
No, you can't build a 50' collinear array legally.
Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
My AP's AC->DC power supply is rated to 1A output at 12V . That is 12W. Given that sunlight is about 2kW/m^2 on a bright sunny day, and assuming a 10% conversion efficiency out of a panel (I think some are 15%), you might only need a panel that is about 25cm by 25cm. It is not all that large.
Say you buy a 30cm x 30cm panel that generates current at 12V and buy small battery pack to store charge in the bright spots and to supplement power when a cloud passes, I think it could easily be done.
I've been thinking of doing a "portable" repeater setup, but using a parabolic dish to bring a wireless connection a kilometer from the base station. I've done a basic proof of reception, I just need to build something like that.
Actually V1.0 WRT54G's use a 5V 2A power supply. V1.1, 2.0 and WRT54GS models use 12V 1A.
Unfortunately they use the same power connector so some unfortunate folks have watched a V1.0 go up in smoke when they mixed up the power supplies.
Life is a tale told by an idiot, full of sound and fury, signifying nothing.
William Shakespeare