Hi Tim,

Interesting concept :-)

Just an idea.
Mount the boom in the center of a thin, broad flexible strip of spring
steel. Make a quadrant with a line of perforations on the edge and use
a pair of slot photo detectors, a bit like the slotted wheel in a ball
mouse to detect the movement. This would do away with the pot and a
cheap mouse IC could do the rest. You could even use flexible pcb on
the strip of spring steel to provide power to the fan motor.

--
Best Regards:
Baron.