Friday, September 09, 2005

How to Make a Backpack Wifi Hotspot

backpack diagramA month or so ago, Popular Science had an article on how to make a mobile wifi hotspot in a backpack. At the time it was published as just an uber-cool way for geeks with a little extra cash to show off their tech props. Given all that's been going on with Katrina, though, I wanted to relay the basics of the instructions here so that people on the ground would be able to implement their own mobile hotspots as wireless broadband goes back online along the Gulf Coast. The whole thing can be set up for around $1,100, but I imagine it'd be worth it for orgs working on the ground trying to maintain communications from the field. For the full details, please see the original article.


• Junxion Box wireless gateway $700;
• Verizon Wireless EV-DO PCMCIA card $100;
• Voltaic Systems solar-charging backpack $230;
• 12-volt battery with spade terminals, 1.2 or higher amp-hour $15
• Male DC power plug, size M $5
• 18-gauge wire, black and red $5
• Female insulated quick-disconnect connectors, crimp-type, sized for battery spade terminals $3
• In-line fuse holder $7
• 20-amp fuse 50 cents


1) Plug in your EV-DO card and set up the Junxion Box to automatically assign TCP/IP addresses using DHCP, and disable the authentication splash page.

2) To build the power-adapter cable, cut a length of red wire and a length of black. Strip one end of each wire and crimp a spade terminal connector onto each.

Strip the other end of the red wire, and solder it to one end of the fuse holder. Wrap the connection in electrical tape. Take apart the male DC power plug. Solder the end of the black wire to the negative terminal of the plug and the red wire to the positive. Wrap the exposed positive connection in electrical tape, and reassemble the power plug. Install a 20-amp fuse.

3) Connect the Junxion Box cigarette-lighter adapter to the backpack “power out” plug.

4) Connect the battery cable to the “battery” plug on the backpack’s charge controller.

5) Take a hike - you're ready to go.