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.
Step 2: Disection!!!!!!
In this next step we are going to have to do what most lego owners would hate to do, take them apart. What we have to do is cut one of your connecting cables in half. If you don't want to do it, either suck it up or order new ones at the lego site, here I'll even give you a linkhttp://shop.lego.com/Product/?p=8529 :) Ok, now strip off a good chunk of the black casing. You will see six wires under it. Cut off the four colorful ones but leave the black and white wires on the end. Now string some of the casing off of them and either twist or tin the exposed wire. This opens loads of opportunities just waiting to happen.
Step 3: The LED
For this step, we are going to use the generator to make an led light up. Get two alligator clips and connect one end to a lead of the led and the other to one of the frayed wires. Then do the same with the other alligator clip.
Use the crank to light the led. If the led does not light however, the polarity was probably reversed which means you must crank the motor in the other direction. If it still doesn't light, check your connection.
Next, get out your multimeter. Wrap the two exposed wires around the two multimeter cords. Set your multimeter to the 20 volts DC setting and crank the motor. I got mine up to 13 volts which I think is pretty good for a tiny little hand crank.
Step 4: Materials for the Charger
We are going to need a few materials to create our charger and this is what you need:
-USB cable for your mp3 player
-Lego mindstorms NXT servo motor
-Lego mindstorms NXT connector cable
-Female USB port
You also need these tools:
-Superglue (optional for step 2)
Step 5: The Female USB Port
First, make sure you have step 2 completed
Now take the turquoise casing off of the female USB port. Take off the copper tape, revealing the clear plastic. Cut the clear plastic in half and then remove the clear plastic off of the female USB port, leaving four small wires. Cut off the middle two, leaving only the outer two.
Step 6: Put It All Together
Now we have to solder the NXT connector cable to the female USB port. We have to make sure that the polarity is correct so we can crank the motor the easy way, not the hard way. Place the port with the 4 "nubs" on the inside are pointing up and so the white plastic side is pointing toward you. Now, solder the white wire on the left wire that is sticking out and the black one to the right wire that is sticking out.
Next, plug your crank onto your motor, your connector cable onto your motor, your USB cord into the female USB port, and your USB cord into your mp3 player.
Step 7: Crank Away!
Now, all that's left to do is crank. make sure everything is connected and then crank the motor. Your mp3 player should show that it is charging and when it is on the charging symbol, keep cranking it on that pace because when it shows the symbol, it means that the voltage is just right.
It works best for short charges when your player needs a little extra juice, unless you like cranking for 4 hours straight.
Step 8: And Beyond....
I put this step in to say that this is open for anyone to add suggestions to. (And to say I'm not responsible if you somehow break your mp3 player doing this.) There are tons of places this could go. I was going to try and attach it to a bike so it would be more reasonable since some people like to go on really long bike rides. Feel free to comment, I'm open to any ideas, even crazy ones like attaching it to your hamster's wheels or something like that. Thanks for reading and I hope your enjoyed my Instructable!