Rotating LED message board

Posted on May 4, 2012

This unit has a single column of LEDs that are spinning in a left to right motion, as it spins a microcontroller keeps track of the exact position of the board. Words are written in the air by flashing the correct bit pattern in the correct location. The same word is repeated over many revolutions of the device, each time the LEDs turn on in exactly the same locations. This works because of something called persistence of vision, the eye retains the image for a split second. This is also the same principle that makes the hard drive clock work. When looking up information about the persistence of vision phenomenon I stumbled across another phenomenon called after images, you must try it.

A variable voltage regulator is used to adjust the speed of the motor. The 6V motor is being powered at about 3V. You might notice that the board holding the column of LEDs is broken and stiffened. This is because the crystal flew off on one of the first full voltage unbalanced tests and broke the column of LEDs.

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