As a simple project for my local radio club I've designed a PIC
Magic Wand that flashes 7 LEDs leaving a trailing message in the
air. The flashing (ie message) is triggered by motion sensored by a
mercury switch.

Works fine if you wave right to left but moving left to right the
message is mirror imaged (of course).

Any ideas on a simple (and cheap) method of detecting whether
motion is left-right or right-left so I can invert the message as
appropriate. 2 mecury switches mounted in some way so that the
leading edge triggered first seems the obvious solution but how to
actually implement this?

Thanks

Brian
Brian E Jones
Centre for Java Technology
IBM HURSLEY

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