>  Joe, 
>   As an alarm designer (fortunately it was a long time ago)

It's your lucky Vasile, you may have the privilege of helping me ;-)

I've got a little alarm project for a small vehicle that needs a
movement detector and have day-dreamed about it for a day
or two. It's a senior school project for a group of  young ladies
(yes, I know, get over it) -

Anyhoo....

"We are SWIPE, a Young Enterprise team. Young Enterprise is
a learning experience for secondary school students. They have to
form a company; become directors; develop products and services,
which they then have to market and sell"

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

So far I've thought of suspending the whole circuit on nylon thread,
or just the wire/ring on thread or a metal chain. It has to be both
sensitive and rugged. The Sensitive New Age Guy of alarm triggers
if you like ;-)

Any ideas ?

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