This technique should be useful for short runs of ethernet (6' or less) and to power pretty much anything that needs 5VDC and doesn't require a lot of current. I've seen USB ports provide up to one amp of current, though it's usually advised to keep it under 500mW. If you have a dual-USB Power/Data cord like the ones that come with external 2.5" hard drives, I'd advise using that to help get more power to the Fon, but there are several people running USB power directly to the Fon, and it seems to work fine. This is the first time I've seen a POE injector/splitter used in combination with USB before. Pretty clever.
This is a guest post by cyb3rassasin, a student in the midwest that's interested in security technologies. You can follow him on Twitter.
Okay, so I’m sitting in the coffee shop with my LaFonera router in front of me, and my netbook on my lap. I look at my fon just sitting there with its 4 AA battery pack, pondering how else I could power this little guy. A battery pack is bulky, and I don’t really want to have to carry a wall wart with me everywhere I go.
So the options that come to mind are usb power, battery pack, and power over ethernet. The first two aren’t bad ideas but I was kinda looking for something a little more compact and cleaner. I decided to look at some PoE injectors/splitters because they’re inexpensive and compact.
The only problem I could forsee is again I’d have to carry a wall wart around with me. Then I thought why not cut the power adapter off the injector and replace it with a usb plug. It would be simple, clean, and I’d only have to have one cable running to the fon. The Fon can run from 5VDC just fine.
I decided to pick up a set of PoE cables from Passive PoE. I grabbed a usb cable from an old phone that I had, I chopped the end off and stripped all the wires. I then cut the power plug off of the injector and stripped the two wires. ( note: the copper is ground and the red is positive)
Now, don’t make the same mistake I did: put the heatshrink on the injector before soldering the usb plug and the injector together. I soldered up the connections, wrapped each individual connection in electrical tape, and heatshrunk it.
Before testing this with my fon, I thought it would be a good idea to make sure I got the polarity correct. I plugged the injector into my netbook, hooked up an ethernet cable, and then attached the splitter. I took a multi-meter and to the splitter and sure enough, I had the polarity right. Center pin: positive 5VDC, outer barrel: negative
Now it’s time to take a leap of faith and plug in my fon, and woot! It works!
So now I successfully have a compact way to power my fon via usb and PoE. I’ve found one downside to this, it drains my netbook battery faster than if I would use a battery pack. Other than that this is an effective alternative way to power the fon.
cyb3rassasin also showed me the Open-Mesh mini router, which seems to be nearly identical to the original Fon2100 shown here. Since the Fon2100 is no longer available new from the manufacturer, and the newer hardware isn't as friendly for things like Jasager/Karma, it's nice to know there is still a comparable piece of gear out there to take its place in our hackpacks. Long live evil wifi! Here are some photos he sent us, comparing the Open-Mesh and the Fon2100.