Step One ... Gather the Equipment
Post date: Sep 03, 2012 10:34:37 AM
First up, the battery pack.
The A10HZ from Maplin, a 5Ah 12v battery pack.
This has 2x6v batteries internally, and a 200W inverter, two accessory sockets, and two 12v terminal posts. It has a usb power socket and a light too, but the usb socket is tied to the inverter being on and the light is incredibly weedy, so we're ignoring them for now.
I now have two of these, both bought when Maplin have had sales on. Not worth £50, in my opinion but for less than £30 they're a must-have.
Next up usb sockets.
Since most low power gadgets have USB power. 1-2A USB accessory gadgets like this ought to work just fine, some of them fit flush into the sockets too! I forget what mine are spec'd at but they all look pretty much the same as this.
Seriously, you've never seen one? Look at the image to the right!
I quite like the ones that have an LED because you know that they're allegedly working, as car lighter sockets tend to arc a bit and corrode.
First bit of tech. The 3G "Modem"
Expansys had the Huawei E355 on sale recently (around £60, cheaper on Amazon, ouch) so I grabbed one of those. These are quite fancy devices, as they have an external antenna socket, and a Micro SD (often named Trans-Flash, or TF) card slot, as well as functioning as dongles as well as a wifi router.
Alas it only allows FIVE devices to connect. Frankly this bothers me, and it's a standard thing across the industry of MiFi devices, who thought that five (FIVE!!!) devices were enough? I usually have at least that many devices on my person if I pick up my laptop bag.
Still, it doesn't need a computer to operate. So I tested it on a road trip to Scotland plugged in the boot of the car in an accessory socket.
It worked flawlessly - Nuff said. A disassembled one and a write up of it can be found here.
Second bit of tech. The "3G Router"
Deal Extreme were selling TP-Link WR703Ns at some point, but I can't find them on the site now :-(. You can still pick them up from pretty much anywhere though (like Amazon).
These things are for the Chinese market (DX being a cheap and cheerful chinese exporter) and often marketed as "3G routers" - however you need a 3G dongle! They're supported by OpenWRT and quite hackable. I've played with the two I have (Imaginatively named A and B) quite extensively. The supplied firmware happily uploaded the OpenWRT images.
And that's all we need apart from miscellaneous stuff like proper antennas and a nice box to put the tech in.