I am really happy to read all the useful and inciteful ideas put forth.

  I realize I did not supply enough information in my original post.

---->  I have been designing a vehicle tail light which would start  
flashing at a slow rate
as the brakes were applied and at a faster rate as the brakes were  
applied harder.
Ideally this unit would be standalone except for power ( which might  
be solar provided ).

I see no way to differentiate between braking and going downhill. Any  
ideas ?   <---

My desire is to build a product that will sell for $30-$50 max.  Less  
would be great.
The product requires NO skill to install.  If it requires power that  
could come from the
cigarette lighter socket.  The user can put it in the back window or  
mount it anywhere
they want.
The desired result is to have the light FLASH to alert other drivers  
to wake up.
False positives are not that bad.  False negatives are to be avoided.
If it works correctly 90% of the time it is certainly better than  
"nothing".

Your comments made me realize that another product could measure the
speed at which a car was approaching the rear and flash the brake lights
if the closing vector was excessive.  In addition, if an Italian  
driver ( note
my last name ) is following on the bumper, the light would flash.

( on a side note: I actually got a driver following me to use his  
turn signals today,
by repeatedly striking the side of my head with my open palm.  He  
started using his
signals and he also flipped me off.    see http:// 
urbanlegends.about.com/b/a/007882.htm  )


ALL OF MY COMMENTS / TEXT/ IDEAS ARE PUBLIC DOMAIN.  PLEASE FEEL FREE  
TO USE THEM.


I really apppreciated Bills comment

\Isn't "x-axis" acceleration due to typical hills liable to be MUCH
smaller than acceleration caused by  even gentle breaking?  Maybe
you can get by with a simple threshold.  Have you measured the sorts
of values that actually occur instead of getting hung up on theory?

BillW

Also the one about a strain-gauge on the brakeline
Possibly the one about monitoring the brake-light will work.
And vibration sensing to calibrate.



yes, inciteful is a pun




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www.omegadogs.com   Denver, CO

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