I have seen many things ( not only Instructables) on generating power with the OLD Mindstorms lego set. However there have been no new ones. Since I couldn't find instructions on how to charge an mp3 player with the NEW set, I set off to do it on my own. I was able to do it, but found many other uses for the NEW lego mindstorms NXT and many ways to create power with it. Mp3 player chargers can use up lots of energy and this can get rid of it all so I hope you like my Instructable and use it to "green" up your day!
(This is also in the pocket-sized contest so please vote for me!)
Step 1: The Beginning
First, we are going to learn about the servo motors that come in the lego mindstorms NXT kit. These are our main tools because they will generate power. We can test this by first connecting a motor to another motor with one of the cables included in the kit. As you spin on of the motors, you can see that the other one spins too, showing that the motor is generating power. This is very basic, but it plays a big role in the final product.
***The second picture shows how to build the crank I used throughout my Instructable, it works very well but it helps to superglue the pieces together as legos can fall apart easily.