I have seen one of the products with the LEDs on the wand. At the time it struck me as quite cool. The wand was a very narrow piece of circuit board covered with black solder mask. It had eight LEDs at the top and was mounted on a spring hinge mechanism at the bottom. The back and forth motion of the wand was controlled by some induction coils near the base of the wand that would alternately interact with a metal flag from each side. As the wand would swing it could display bright red LED charcters that had the appearance of hanging in mid air. It was rather cool. Here is a crude sketch of how the contraption was made. As I recall the software in the thing could even display a long string of characters in a slow scroll across the display area of the wand motion range. Measurement of the wand position was detected at the extreme ends of wand motion range and the timing of when to multiplex pixels to the LEDs must have simply been done via a timer interrupt.




I always wanted to build one but for some reason never did it.

Michael Karas