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A hand-powered webserver

Have you ever thought it'd be cool if you could have an environmentally-friendly computer ? I've always wanted one, I even powered my old ZX81 with a bicycle, a dynamo and a bridge rectifier circuitry once. Trouble is, even the poor little ZX81 needs a lot of pedaling to simply boot up.

Then, on Friday, I came across this hand-powered lantern while browsing the net, and the idea clicked in my head : the manufacturer of this little gem ships it with a 3V 650mA light bulb (1.95 W), and the uCdimm from Lineo needs 3.3V 350mA (1.155 W) at most, so the lantern should be able to power a uCdimm confortably.

So I called up a bunch of places here in Toronto and found one of these lanterns. When I came back to the office, our local electronics guru Sergey, our local geekhead Evan and myself took the thing apart, cranked up the spring and measured the voltage : without the lanterns' battery and light bulb, the internal DC generator spews out a heroic 5 V. Cool, that's perfect for a 3.3 V regulator and a uCdimm !

So I spent the week-end cleanly ripping the guts of the lantern out (it's surprising the amount of electronics this thing has inside), installing a 3.3 V regulator inside, a serial port and an ethernet port at the back, rewiring the power plug that used to serve as battery charging port to power the uCdimm while working on it, rewiring the button (that is also a clever brake to stop the spring from unwinding when the lantern is not in use).

The hardest was soldering a bunch of wires on the uCdimm's bus (man! those pads are tiny) and installing it nicely in lieu of the original light bulb and reflector.

One nice thing about the uCdimm (apart its low power consumption of course) is that it boots into Linux quickly, which is crucial because the dynamo only provide a little over 2 minutes of power with 60 cranks, so every second spent booting up the board is a second lost that can't be used to browse.

So here it is : the "uCdynamo", the first webserver you can bring with you and use in a desert :-)


The uCdimm embedded in the front bezel, with a background image to make the whole assembly look a little better.
The spring ran out of breath before I could finish taking the photo :)


The side of the lantern, showing the business end of the muscle power supply.
The button controls the brake applied on the generator's large pulley, and the reset line on the uCdimm at the highest setting.
The power led next to the button now serves as "health" monitor, just like on the uCevolution board.


The serial port, ethernet port and additional power plug sticking out at the back of the lantern.


The guts of the beast. You can see the gears demultiplicating the huge torque and low speed of the unwinding spring into a low torque high speed rotation to operate the generator.

Jeff reckons the generator has enough oomph to power an LCD display as well, and there's plenty of space left on the side of the lantern to bolt one on, so maybe we'll turn it into a hand-powered "handheld" some day :-)

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