I'm about to go on a plane, and I've seen some phone plugs for people who wish to send faxes or place a call using the plane's phone system.

I was wondering, since my flight will be many hours long, if I could make a custom wire that could use the power from the phone line to charge or simply keep my zaurus's battery from running out. If I can garantee a 5v 1A power through some converter or something, that could be useful..

I'll do some research on the web to see if it's possible...

Not likely but a lot of planes have car cigar lighter sockets under the seat. It's worth a look. It is also possible that there is a jack to power sound cancelling headphones that you can draw power from.

I seriously doubt a phone jack provides enough power.

Why not just use an external battery pack to prolong the runtime? Since the Sony PSP uses a compatible power plug, there are plenty to choose from.

You could also use a USB charger if you have a laptop. (or if you're sitting next to someone who does. )

Battery pack would be nice.. but for a 16 hours flight, not sure it would last that long

I just started using the socket battery pack. It is rated at 5V 7200mAh. I was able to recharge my Z 3 times with it and still have some juice left. I will use it as the power source on my next long trans-pacific flight next month and see how it holds up.

Go the other way round it will be quicker

You didn't say what model Zaurus you have, but you can easily compute how much battery you need.

I'll take as an example my SL6000. I haven't measured it recently, but let's say it runs for 5 hours on the internal battery. It's a 1500 mah battery, although it's used so the capacity is actually less. But we can use the stock rating as a conservative estimate.

So, I would get 5 hours from the internal battery, that means I need 16-5=11 more. That means, I would need an extra (11/5)*1500 = 3300 mah worth of juice. Back of the envelope calculations for sure, but it's probably in the right ballpark.

You can easily get this much power with 8 AA or 4 C batteries.

I think its best to leave the internal Z battery at full charge while running off the external pack. This is because recharging the internal battery is an inefficient process that wastes energy. (if this advice is wrong I hope someone corrects me)

I do not have it yet, but I'll be getting either SL-C3000 or SL-C3100

It not recomended but you can draw power from your telephone lines for standard home phone lines and have your phone company pay for the power costs but if they caght you it would be game over (plus you risk damadging the equipment)

for a couple of LED's it would be fine but not enogh to charge a zaurus, that and you would have to regulate a 40v supply which is beyond most linear regulators

I'm don't know much about electricity circuits, It might simply not be enough. If it was just enough to power the Z while on the plane, that would be nice, but risking damage to the Z is a no go

It should be possible to protect the line against sudden power variations with a small circuit.

Thats not the problem, if you have to use a power converter instead of a linear regulator so instead of just droping the voltage to the desired level, you drop the voltage and use that droped voltage to generate more amps (i over simplified here) however on a plane the circuitry could be diffrent, and hooked up to the planes egines

the loacl equivelent of radio shack (jaycar) sells 9000maH battries (D sized) so whipping up your own high capacity batterypack is going to be easier than learinig electronics/getting all the equipment you would need to build the telephone plug charger

I've had a 5500 running off of 8xAA NiMH batteries for about 20hrs straight.

I just picked up 2 6000mAh litium ion batteries designed for the PSP, when i get them i will do some battery life tests

from what i can make out from the pictures they are a bit smaller than a cigerette pack

thats what fuses are for ...

i had forgoten abunt this but dont airplanes have special sockets that provide power that you have to pay stupid amounts of maney for the socket converter?

i just saw a kit that had every type of connector for use an planes

fuses are good for current but i was refering to a diffrence in the voltage you expect and the voltage you get plus other things such a noise on the line from the mechanical systems