Electricity

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The Laptop can work on ordinary electrical power, or can be charged up using a hand crank. Schools will need power to run the school server and Internet connection. Even if regular electrical service isavailable, schools need to have an Uninterruptible Power Supply, probably containing a diesel generator, that can run indefinitely in case of major power outages. We can consider other alternatives for low-power servers with perhaps a few car batteries or a marine battery.

Pointers to projects doing this in the field, please. We don't need links to the general literature, which is easy to find through either Wikipedia or Google.

Solar

Hardware Idea

What do you think about the idea, to integrate solar cells on top of the xo? The laptop is 24 x 22 cm large. I've read that an average solar cell produces 160 W/m². Then the laptop would be capable to produce 8 Watts on his own. The Laptop only needs on average 3 Watts. I don't really know how much energy can be produced by solar cell, if it is in the shadow.

You can integrate the produced watts in two different ways. Either this energy could be used to load the batteries, or it could be used to support/reduce the energy outpout of the batteries (like the system used in hybrid cars). This would possibly expand your battery lifetime.

Mechanical

I realize that mechanically, a hand crank is not a good idea for the OLPC.

However, this weekend I bought an ingenious LED torch (flashlight).

It operates by using a 15mm magnet that slides inside inside a 9 mm tube that in turn is surrounded by a 25 mm bobbin at the centre of the tube. There is a rubber buffer at each end of the tube to absorb excess impacts and to encourage the magnet to re-enter the coil in the reverse direction. The user just gives the torch a shake, and this shaking charges up the capacitor and hence the battery. The minimalistic pc board contains an on-off switch, full wave rectifier connected to the coil, a current limiting resistor in series with the LED and switch, and is connected to what looks like two disc batteries in series, connected in parallel across a capacitor, and in parallel with the direct-current side of the full wave rectifier.

Similar devices are shown e.g. at http://www.vidcam.com.au/sales/faraday.htm

and at http://www.hc-gifts.com/3_Eternity_Flashlight_Hand_shaking_Forever_Flashlightsmall_623.htm

I was wondering if such an idea could be incorporated horizontally into the base of the OLPC so that when the child walks to school carrying the OLPC, the natural movement charges the laptop.

I have been running this torch most of a weekend, without any deliberate shaking of it, and it has not yet extinguished itself!

Certainly, the OLPC load is more that a single bright LED, but I think this approach will have promise, especially in developing countries where there is no power at home or the school, without the problems incurred by the mechanics of an external crank. --Olpcme 08:49, 31 May 2007 (EDT)