We recently built a LED spinning top with message display. Its an improved version of a similar top published by Elektor in their December 2008 issue. The Elektor top can be spun only in one direction. The synchronization required to print message on the LEDs arranged along the radius of the top is achieved by detecting the earth’s magnetic field.
Demo
video Direction Aware Messaging LED Spin Top
Our top can spin in either direction and print a message accordingly. In our improved version of the spinning top, we used 2-channels of magnetic field detector circuit placed 90 degrees apart along the circumference of the circular PCB, to provide quadrature phase output that allows the top to detect the direction of spin and thus is able to adjust the LED pattern appropriately.
Read more: Direction Aware Messaging LED Spin Top using Tiny44 microcontroller