mass + spring mounted to a linear POT
poor mans acceleromiter
take readings when car is armed for the "parking on a hill" effect
size of mass + spring should get over the sliding friction of the pot
not for production as it'll break pdq general driving wearing the pot out
one of those at 45 deg to the cars direction of motion
pick up side impacts and "towing" activities
(thaught for a "feature" calibrate it such that if it picks up a reading its
>20 degrees for a sustained period (ie being towed) the alarm cuts off)

PIC with ADC and look for a movement outside the noise
perhaps a fairly high speed sample loop looking for a movement of the ADC
value over say a 5 point moving average as a poor mans low pass filter for
the high speed noise, then the low passed movement is the movement of the
car, if that breaks some "magic number" then its set off.

it'll be finiky and but probbly "good enough" that your average assessor
will not to see all the flaws straight off.
question you gotta ask is what level of acceleration is too much

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Jinx
> Sent: Friday, May 27, 2005 21:47
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE]:Trembler/tilt switch
>
>
> > Have a look at the vibration sensors from Signal Quest ( P/N SQ-SEN-
> > 003P / 3PS / 3PS-XL)  http://www.signalquest.com/
> >
> > They're basicaly a ball in cage design, but all the parts are
> gold plated
> > and sealed. I used some in another project - my only complaint would
> > have to be price, about $5 US ea in low quantities. But I'm sure they'd
> > send a few samples if you told them what you're doing
>
> Good food for thought Denny, thanks.
>
> Forgive me if I've mis-read the pdf,
>
> http://www.signalquest.com/SQ-SEN-003P%20-3PS%20-3PS-XL%20Omnidire
> ctional%20
> Tilt%20and%20Vibration%20Sensor%20Datasheet%20and%20App%20Notes_20
> 05-01-24.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 ............
>
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