frequency Shifting/Transposing - How ???

Thread Starter

Napoleon

Joined Dec 21, 2008
47
You know, virtually ALL speedometers have SOME method of calibration.

It sure would be easier (and more reliable) to simply calibrate the speedometer itself, than try to kludge in some makeshift circuit.

It may be simply that water or other contamination has entered the speedo housing, and is causing a lower than normal resistance in a portion of the circuit. Careful cleaning the board with 91% isopropyl alcohol may simply make your problem go away.
I could open the meter gauge and see if there is any adjustment there.

But, FYI, this error is by design.
Pretty much all motor bikes will read about 5-10% high.
It will depend by manufacturer, but it is engineered that way.
The meant for it to be off.

Unlike with cars, where they are pretty close to accurate.
 

Bernard

Joined Aug 7, 2008
5,784
Back from Mexico. I have a gut feeling that the 555 as V to frequency is not too linear; how about a new face on speedometer?
 

Thread Starter

Napoleon

Joined Dec 21, 2008
47
With a digital readout? That seems like something that you should have mentioned. Maybe it didn't seem important at the time. Maybe it isn't.:D
Sorry if I missed mentioning that, and it would have made a different in the outcome.

I guess I wasn't thinking that the way the speed is represented would affect how the pulses could be modified on their way to the gauge.

:(
 

Ron H

Joined Apr 14, 2005
7,063
Sorry if I missed mentioning that, and it would have made a different in the outcome.

I guess I wasn't thinking that the way the speed is represented would affect how the pulses could be modified on their way to the gauge.

:(
I think you are correct. It doesn't matter.
 

Thread Starter

Napoleon

Joined Dec 21, 2008
47
I think you are correct. It doesn't matter.
:cool:

I guess I will try opening up the gauge and see if I can spot the circuit area that takes care of the speed display and maybe that can be modified to adjust the reading.

I think its all SMT so it might be a little challenging, as I dont have any SMT stuff.
I have used a regular iron to jimmy-hack some SMT stuff, but certainly not pretty.
 
I've just built a circuit using the LM331. Using two, one as a freq to V converter and then a V to F converter, using the circuits in the data sheets. It gives an asymmetrical square wave output. I'm planning on using it for my BMW speeedo correction.

If anybody knows how to do this digitally, I would be interested. Hope this helps.
 
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