Here's a cool idea. Mount LEDs in the walls of your fan and strobe them to create interesting effects on the fan blades. You can make the blades seem stopped, rotating in reverse, rotating more slowly, and other cool effects. The published circuit is real simple, and the strobe rate is controlled by a potentionmeter. The circuit includes two pots, the 1 megohm is for coarse adjustment, and the 10K is for fine adjustment of speed.
-1 piece 74HC14 (cost ~ 50 Cent)
-1 piece BC547 (cost ~ 10 Cent)
-1 piece 10 kohm potentiometer (cost ~ 5 Cent)
-1 piece 1 Mohm potentiometer (cost ~ 5 Cent)
-1 piece 40 ohm resistor (depending on how much / strong leds are used) (cost ~ 2 Cent)
-4 leds (my one are 1,5 V @ 20 mA) (cost ~ 50 Cent)
-1 capacitor 0,047 µF (cost ~ 10 Cent)
There are other approaches too.
Here's a Bit-Tech article on how to do a "rainbow" lit fan.
You could also just mount the LEDs in the fan wall and leave 'em on, for example.
All material © 2001-2006, Robert W. Warfield.