Jinx opined:
> Someone they approached suggested mercury tilt switches, but 
> in my limited experience with tilt switches, they aren't all 
> that sensitive and aren't very good for detecting motion, 
> like a small vehicle being moved. I've suggested that a 
> pendulum trigger would be better.
> Simply a hanging wire in a ring (both gold-plated) that would 
> sway, as it has far less inertia than a mercury switch (even 
> if the mercury switch is set at some teetering angle). The 
> wire/ring is how the TILT switches in pinball machines 
> started off. And they work - I've lost many a 20p being too energetic
> 
> One complication is that the vehicle probably won't always be 
> left on level ground, so I've been trying to think of a 
> simple way to make this pendulum switch self-levelling, or 
> another type of switch as an alternative
> 

A metal ball inside a "cage" made from loops of wire. The cage is curved
(the loops at the ends are higher than the loops in the middle) so that the
ball will come to rest away from the ends even if the truck is not level.
Each wire loop is electrically separate and connected to a PIC pin. Scan the
pins looking for which loops are shorted together by the ball. If the short
moves, so did the truck.

---
James.


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