On Fri, 17 May 2002, Alan B. Pearce wrote:

>>How about a pair of simple mercury tilt-switches?
>
>>Check out the Analog Devices accelerometer series,
>>specifically the ADXL202 devices and their
>>application notes. They will do this for you.
>
>Well the ADXL devices have the advantage that when you turn the car off they
>can remember the current angle of the car (well your software would be doing
>this) and then if that changed before the car was started again then the
>alarm goes off. An allowance would need to be made for the car rocking in
>the wind or any other activities .... no lets not go there .... and it then
>means that it does not need manual calibrating if parked on a hill.

As a general rule alarms operate when the car is not operating. Why would
you store the 'previous' 'horizontal' level ?!

There is a 'slight' price difference between the ADXL devices and
electrolytic tilt sensors, also, the ADXL is more sensitive to impacts,
shaking from wind, etc.

Peter

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