Re: updating guages in MK1

[Brad Sheridan <brads@mindspring.com>]

At 08:52 PM 12/2/98 +0000, you wrote:
>A wierd crazy thought came over me the other day. I was looking at 
>the speedo in an Audi 5K and thought "I wonder if there is some way 
>to change over to an electric speedo in my '81?" What do you think?  
>There's got to be some way to change over to more accurate guages.  
>The tach bounces when you hit a bump, reacts slow, and is inaccurate. 

  I've dealt with this a bit at work. There are some tradeoffs between
reaction time of the tach, and smoothness of operation. Most tachs have an
internal low pass filter on the electronic signals they receive. A small,
or no filter mmakes the tach respond instantly. It also makes the thing
jump all over the place. A larger filter makes the operation seem much more
smooth, at the expense of a little slower reaction time. The only way I
could think of making an analog appearing tach with quick reaction time,
and a smooth appearing function, would be to get rid of the standard meter
movement, and go with a stepper motor. You would then have to have some
sort of interface that would be able to read in the tach signal, and
control the motor accordingly. I have seen this done, on the new CBR900RR,
it comes stock. It may be possible to modify that tach to fit. Otherwise, I
don't know of any cars that use a stepper motor, and I don't know of any other
goow day to get quick reaction time, and smooth response at the same time.


HTH,
Brad


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