Cheap DC-DC upconverter for USB?

[leadbelly]

I fly on airplanes that provide a USB port at each seat for power fairly frequently. I would love to take that 5VDC and use it to trickle charge either my portable DVDP (9VDC) or my laptop (18VDC) to just get a bit longer use on batteries out of them, even though not a full charge. Is there a cheap DC-DC upconverter that I can use for this?

[Bootstrapper]

Even if there would be, most likely the USB port doesn't give many watts. Usually a computer USB port gives roughly 500 mA max. so that makes 2.5W total. This is certainly inadequate for most of applications, not to mention feeding a laptop!

Was this anywhere close to what you were looking for? I might have misunderstood something. In that case, yes, one could easily implement a simple boost converter for 5V -> 9V conversion. Try Linear Technologies, they have at least one suitable DC-DC converter that requires only several external components.

[leadbelly]

Yes, this is almost the perfect answer I was looking for, except I would prefer a non DIY solution, something already built that I could just solder on my own specific connector. I know about the current limiting, that is why I referred to it as a trickle charger.

[wakibaki]

2.5 Watts, the standard, which will charge a mobile phone with a (readily available) adapter is nowhere in the laptop world.

A Sony DVP-FX810 player requires ~20 W. After losses in conversion your ~2 watts won't go far, even if the player will let you take advantage of your adapter without trying to draw too much current. Who knows how the output is arranged, you might blow it for the next guy.

Yes, a boost converter is not too difficult to build but you'd probably do better with a solar cell in the window in daytime.

Anyway, although I think it's unlikely to cause a safety hazard, I wouldn't dick around with stuff in an airplane.

w

[leadbelly]

That's pretty funny. So all these cheap commercial electronic devices around us have fold over supplies that can't be damaged by a short, but the $100 million plane won't? Boo!

[alan-1-b]

Hi Leadbelly,

Osama Bin Laden is probably dead, and his crew know the propaganda value of keeping him as if alive.
This may keep Dubya Bush confused in mind, and that doesn't seem hard to do as you obviously know given your great sub-line
which I like a lot, and I thank you for Posting it !

As for plugging in your device(s) to the airplane's USB power port and draining their power supply, well you might bring the plane down, and that'd be taken as another score for Bin Laden's crew and poor old Dubya Bush would be leaving Office with another problem taxing his weary brain ...
Well, we might get a good sub-line from what-ever Bush may utter after such event, or you might get arrested on the plane when they see you plug in your terrorist device ... thus my Title line ...

Now your Namesake may have had a song about this, as prescient as he seemed to be !

[jackinnj]

i was an airplane seat tester for a bank at one time, and believe me, they aren't gonna let you even bring anything with DIY-wires onto a 737 or A320.

besides, any switcher you build is going to radiate noise --

some folks scoff at the notion that interference from a cell phone or blackberry will interfere with the nav system. when my blackberry gets pinged at 8,000 feet in our Aztec the autopilot responds.

[leadbelly]

Your latter point is very good, but AFAIK the former only applies to you guys and not this side of the border.

[wakibaki]

Comforting to think then that you live in an enlightened country and that if you do decide to endanger yourself, the other passengers, the pilots and people on the ground and a $100M economic loss, at least nobody will attempt to interfere with you.

There's no point in arguing about airline safety, which was just a secondary consideration, after all it can be dealt with with good design. No, the 2.5W is the killer, plus there are issues around how the power might be used, there are a zillion different brands out there. The device might be able to splice the power into the system and ease the load on the battery, it might not. You could take the battery out and charge it directly, but then you can't use the device for hours. A laptop battery is ~70 Watt Hours. Just carry a second battery if it's that important to you.

People run all sorts off their laptop USB ports; maplights, phones, mp3 players, mini fans, ...but not laptops.

If there was any real mileage in the idea I'd be happy to help you try and make it work, but it probably wouldn't be necessary as you'd be able to get one for $4.99 from China. Olympic USB laptop/DVDP life extender with selectable output voltage and 5 interchangeable power jacks. Complete with CE mark.

Actually it sounds quite useful, but for running low-current prototypes on my desktop... and that's too specialised for mass production. Maybe somebody makes something out there to run higher-than-5V low powered doofers. Good luck.

w

Oh, it just occurred to me. You could make an auxiliary power pack to drive your devices, with a built-in boost regulator, 18V or more of Lithium cells or NiMh or WHY, and outputs at whatever voltages were required with buck regulation for these, for efficiency. You could plug it in when you got on the 'plane and switch over to it whenever the batteries on the other things ran out. Plus you could design it in such a way that it could continue to draw power from the USB while supplying power.

[leadbelly]

Originally posted by wakibaki
Comforting to think then that you live in an enlightened country and that if you do decide to endanger yourself, the other passengers, the pilots and people on the ground and a $100M economic loss, at least nobody will attempt to interfere with you.

You guys who can't let this go crack me up. Do you really think they design the plane so that if somebody plugs in a commercial device with CE, UL, CSA, whatever else, but has a short, it will bring down the plane? And if switchmode devices are such a threat, what about the AC outlets on the big planes for laptops, do they inspect the laptop bricks at security, confiscate the switchmode ones, and let pass the linear ones? And if you actually READ my post #3 and see that I was looking for a commercial device, you expect security to notice a 1" length of shrink tubing on a cable (the only clue that something is changed) as a dangerous device?

Originally posted by wakibaki
but it probably wouldn't be necessary as you'd be able to get one for $4.99 from China. Olympic USB laptop/DVDP life extender with selectable output voltage and 5 interchangeable power jacks. Complete with CE mark.

If you actually had read my post #3 before embarking on your novella you would see that that is what I requested.