02GF74
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| posted on 1/3/07 at 09:01 AM |
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electronic speedo
qucik question; I believe these work by having a stepper motor move a pointer so if you turn of the ignition and the car is not stationary, I assume
the pointer will not be a 0 mph?
So when you power up, does the pointer move to repositioning itself to 0 mph?
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tks
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| posted on 1/3/07 at 09:20 AM |
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wait
you say a couple of things....
reset is always done by a fixed point in your case it would be a pot meter connected to the shaft ( i guess)
wich will tell you where the 0 is... where the 30 is etc. etc..
ot just only the 0 and x steps per km/h..
in this case its easy for the clock to reset it self and after reset it could start listening to the speed sensor.
in case you have a different speedo it wouldn´t be a problem to because knowing its in the down position (below 0)
it will know the offset to 0 + steps per km/h sow it will remark the correct speed....
there is only one excemtpion and thats when you cut off and directly turnon, then it could be marking 0 and readd the 0 offset.. thats the reason i
prefer the potmeter tactics... also if your sensor goes out on higher speed you could recompensate easyer...
Tks
The above comments are always meant to be from the above persons perspective.
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MikeRJ
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| posted on 1/3/07 at 12:32 PM |
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quote:
Originally posted by 02GF74
qucik question; I believe these work by having a stepper motor move a pointer so if you turn of the ignition and the car is not stationary, I assume
the pointer will not be a 0 mph?
AFAIK only the posh ones (e.g. Stack) use stepper motors, the electronic car speedos I have seen use a simmilar movement to an electronic tacho, i.e.
moving coil meter. In fact you could use a tacho as a speedo if you could get the correct pulse rate into it.
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