G-Tech meter

[David Doddek]

Could I get the source for the accelerometer cell.  That could be fun to
experiment with.  Maybee try 3 axis and compensate for hills and turns.


>I sawthese advertised and thought that it would be simple to make up 
>my own.  Sure enough within a week I had a fully built and working 
>accelerometer.  The one that I built is programmable for the 
>acceleration speeds, i.e. you could time 50 -70mph or 0-100 if you 
>wanted.  It uses a 24 * 2 character LCD display and does maximum hold 
>values for acceleration and braking as well as cornering force.  The 
>distance calculation is done from the acceleration, the calculations 
>are very simple to do.   The most expensive parts for it were the 
>accelerometers which were u25 each but are good quality accurate 
>ones.  There will be problems with going up and down hills and when 
>you do not accelerate in a straight line.  The distance that the 
>measurement is performed over is usually quite small so that errors 
>that come about from the double integration required are quite small. 
> I am going to start some work on version two which will have more 
>features such as storing the data at various points and automatic 
>recalibration for accelerating round corners.  As for the 
>performance.  I can't speak from experience of the G-Tech meter but 
>mine is very good on consistency.  The timing is atarted 
>automatically when an acceleration of more the 0.05G is detected so 
>that false starts from vehicle vibrations are not a problem.  If you 
>are interested in this and would like some help with the calculations 
>I would be glad to help.  The work on the microcontroller was done on 
>an 87C752 which is basically an 8052 core with built in EPROM and RAM 
>and ADCs.  From what I've heard the G-Tech meters and accurate to 
>within 0.4seconds and repeatable to within 0.2 seconds.  This is from 
>some review in a magazine.
>
>Martin
>
>
David Doddek     pantera at pobox.com    www.pobox.com/~pantera    217-422-3722
69 EFI Fairlane, 89 T-bird SC, 74 Twin turbo NOS EFI Pantera (I like to go fast)