However you can drive by it real close and failry fast with a van or bus
and have alarms. If the bus runs on shedule all hight there will be a
crowd of fans looking for you (the designer of the alarm) fairly soon.
About 5% of the installed car alarms are too sensitive and go off for no
reason (thunder, bus, fat cat jumping on hood etc).

Peter

On Wed, 22 May 2002, Roman Black wrote:

>I've repaired some commercial car alarms etc,
>the standard system is very cheap and simple.
>Usually using a fine spring about 3cm long
>with a weight at the end. The other end is
>soldered on a piezo or in some systems the spring
>goes through a metal loop, so when it vibrates it
>touches the loop and provides a closed circuit.
>These work very good and are cheap and easy to
>make, you really can't bang the car, or jack it
>up at all (even horizontal jacking) without the
>alarm being triggered.
>-Roman
>
>
>Alan B. Pearce wrote:
>>
>> >> You do not want to store the previous 'horizontal' level, you want to
>> >> store
>> >> the current level when you park, so if you do park on a hill you do not
>> >> need
>> >> to go and tweak some control to level the sensor.
>> >>
>> >I guess a potentiometer with a weighted arm hung off the end
>> >would do the trick?
>>
>> Well it could do for a simple system I guess. See my previous posting on
>> what I envisaged one could do with an accelerometer. Got a couple of these
>> things, must give it a go :)
>
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