> http://www.signalquest.com/SQ-SEN-003P%20-3PS%20-3PS-XL%20Omnidirectional%20
> Tilt%20and%20Vibration%20Sensor%20Datasheet%20and%20App%20Notes_2005-01-24.p
> df
> 
> but don't these suffer from the same problem as a mercury switch ? Say
> the cylinder is mounted horizontally in the veehickle. If it's then parked
> on an angle (hill, verge etc) the angle could be great enough for the weight
> of the ball to hold it steady and not respond to small tampering vibrations
> ?
> 
> A couple of other points - I've less than 3 weeks to get this marketable at
> a sale price of NZ$40-$50. Wish I had more time. Really wish I had more.
> Basically anything not OTS is out, the lead times are just too long
> 
> I'm wondering what I could do with something springy ............
> 

Clarify something for me, do you actualy have to "build" these, or is
it just a exercise in design? In which case lead times should be less
relevant. But either way if you're interested, give them a call. I
recieved modest quantities ~100 in a FedEx envelope next day.

As to the alignment issues, in practice the ball is very sensitive to
motion and vibration. My application hooked it to a interupt on change
pin on a 16F675 and flashed some LEDs. Total project weighs about 2Kg
and in practice it triggers if you walk next to the table it's on -
quite sensitive. The app notes sugggest some useful digital filtering
techniques to attain differing levels of sensitivity. And ISTR one of
the app notes specificaly described an automotive alarm.

-Denny

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