Voltage from a Fan

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So I was playing with my previously mentioned computer fan when it randomly started lighting up. I had placed the two contacts of the positive and negative terminals together and place the xion fan in front of a larger more powerful fan and the LEDs inside began to flicker. The reason is the small solenoid on the inside of the fan with a round bar magnet inside of it. When the magnet began to spin the change in area and theta of the magnet caused the current in the fan to move. By hand I could not light it up because the fan moved too slowly. Even with the fan it only slightly lit up. LEDs dont require much voltage and have very low resistance so the current produced by spinning the fan was very, very minisucle. Unfortunately the light in my room makes it very hard to see but if you look very carefully at the corners of the fan, its slighly glowing (mostly the bottom left corner)

Thanks for reading,
Mark.

First Robotics Competition

So in about a month the first robotics competition will be held down at the volley ball stadium at the University of Hawaii and this is a picture of our team with this year's Iolani robotics FRC robot. The tricky thing about this competition is the surface on the ground. This white material is "regalif" or regular glass shower liner. This combined with a special plastic on the wheels give it a coefficent of static friction of .05 making it very hard to drive. The reason for static friction and not kenetic friction is mostly because a wheel uses static and not kenetic. The point on the wheel doesnt want to slip and so when it slips you move slower and dont speed up as fast as if you started slowly and moved faster. The shooter in the center is actually a baseball-ish pitching machine in the sense that the wheels spin really fast so when the plane of the wheels touch the orbit ball the orbit ball moves at the same speed as the plane of the wheel. This allows a fast efficient shooter and gives backspin allowing the ball to fall into the trailer rather than climbing out as would forward spin.

Its kind of late, but thanks for reading
Mark.

Holonomic Drive

Today I was talking with some of my team members, from the 'Iobotics robotics team, about what we were going to do at the 2009 Vex Worlds competition. The idea of holonomic (omni directional) drive came up which brought up an interesting discussion on how to do it and which motors to use and at what power. I did some calcualations on velocity of the wheels and the direction that the bot would travel and came out with pretty simple equations. But for power versus direction it would be slightly more complicated, to do. Because the motors need to follow a polar equation of direction theta vs percentage of power r. The wheels which are parallel to each other have the same power no matter the direction. They follow this equation with the front being at theta = 90. for the top left and bottom right the equation is R = cos ( theta - 45) and the other two it is R = sin (theta - 45). Yet these are not the exact equations to follow because power in the 1.5 amp motors isnt directly perportional to the speed of the motors. Also we want max speed to be max speed not a slowed speed especially when driving forward. The equation is not acutally correct also, because this represents top speed being the sum of each motor, but it would be good to follow a continuous algorythm rather than a broken one/piece wise as we would do other wise.

Phew, long post of an incomplete train of thought...
Thanks for reading

Mark.

Xeon Fans!

So the other day I was messing around with a few batteries and a light switch, to complete and disconnect the circuit. I used two D batteries in series with one nine volt battery to produce a total voltage of 12 volts. This is the voltage required to tun each fan. The amount of coulombs per second, or amperes is .2A which, drained my battery pretty quickly. It only took about two hours for the fan to completely drain the battery. It is a pretty big resistor because it is running a fan, and four LED lights because it has to look cool as well as perform. Though the fan wasn't very convenient because of the battery size it still worked. The potential energy started at a multiple of 12V and was used up to run the fan. This picture to the left is what it is actually used for. It connects to the heat sync which acts like a radiator and pulls hot air toward it and quickly cools it down.

Sorry about this late post :P, Thanks for reading, Mark.