The Shark Scanner gets its name from the party it was designed for. Some friends of mine hold a Pool Shark Party each summer. It's become a tradition. The intent of the Shark Scanner is to entertain people by displaying images in a nearly subliminal way. The effect is rather striking, especially on inebriated observers.

The Shark Scanner is a vertical line of flashing LEDs (see the picture). It is constructed to fit inside a fluorescent tube protector sleeve, allowing it to be water-tight (important around pools!). It is powered by a 6 volt wall bug. The LEDs flash in a sequence so that if you shift your eyes at the right moment, an image will briefly appear as an afterimage. The effect works best in low ambient light, when afterimages won't be overwhelmed by other light sources. The images you will see are shown in the block diagram.

The Shark Scanner is hung vertically from a hook on its top end. The bottom end has the power jack that goes to the wall bug (AC adaptor). The whole thing is about 2 feet long. There are 32 LEDs running from top to bottom, for about 16 inches. The last 8 inches contain the control unit (see the control unit schematic). The LEDs are assembled in 4 groups of 8 LEDs each. Each group contains a shifter and driver (see the light unit schematic).

The images are read out of an EEPROM and shifted into the LED displays. The display rate is about 60 images per second, or 16.6 milliseconds each. The image contains 32 vertical slices that flash the LEDs at the proper times plus another 32 slices that are completely blank to allow for spacing between the images. So the LEDs flash for 250 microseconds per slice.

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