Scale output of Potentiometer

Discussion in 'General Electronics Chat' started by adamj12b, May 15, 2009.

  1. adamj12b

    Thread Starter Member

    Mar 3, 2009
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    I have a potentiometer that has range of about 202 ohms. The range is about 982 to 1184 ohms. I need some way to scale the output of this to 0 to 5k ohms. Maybe somebody could give me an idea of how to go about doing this. I am not able to change out the pot either, as it is built into the application and non removable.

    Thanks

    -Adam
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    What is the application?

    Why you need to make this change?
     
  3. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Obviously this pot is part of a chain of resistors.
    It could be a trim pot used as a variable resistor or an actual pot. What do you mean by 'output'?

    Mik is right we need more information.
     
  4. adamj12b

    Thread Starter Member

    Mar 3, 2009
    15
    0
    Hello. Sorry I was so vague. It was late and I was tired.

    The potentiometer is on a drive by wire accelerator peddle that I purchased for an EV project. The peddle has 3 potentiometers in it. I will attach a picture of the small circuit board in the peddle.

    Again, I am sorry for not being clearer. By output I meant resistance.

    In the first picture I attached I filled in the measured resistance. In the second picture I showed the board as well as the wiper assembly. I hope this helps. If not just let me know.

    -Adam
     
  5. adamj12b

    Thread Starter Member

    Mar 3, 2009
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    I figured I might have confused someone by telling about the 3 pots in the peddle. I only need one of the 3 to work.

    Pot 1 at the top of the pic, pin 2 for the wiper and 4 and 5 for the outputs.

    Pot 2 in the middle of the pic, pin 3 is the wiper and 5 and 4 for the outputs.

    Pot 3 at the bottom of the pic, pin 8 is the wiper and 5 and 6 for the outputs.

    I hope this helps.

    -Adam
     
  6. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Yup yo sure confussed me.

    Even an attempt at explaining the circuit would be more informative than the picture.
     
  7. adamj12b

    Thread Starter Member

    Mar 3, 2009
    15
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    Ok, I see how that picture could be tough. I created another pictorial of how the pot circuit lays out. So on one side of the pot is a 145 ohm resistor, on the other side a 206 ohm resistor and on the center pin there is a 788 ohm resistor. When the pot is turned, the resistance between the first pin and the center pin increases by 200 ohms. I need the resistance range of this pot to be 0 to 5000 ohms for my application. I hope this is easier to understand.

    -Adam
     
  8. studiot

    AAC Fanatic!

    Nov 9, 2007
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    I don't see how your circuit could generate the readings.

    The resistance between terminals 1 and 2 must change in the opposite sense to the resistance between terminals 2 and 3 if your circuit is correct.
     
  9. Dr Oetker

    New Member

    May 21, 2009
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    0
    Hi,

    Your numbers don't match, but it is likely that you have some contact resistance on pot's moving part. Also, the min-max reading are mixed up, but nevertheless, I know what you need to achieve. While it is possible (and easy) to scale down pot's range it is not possible to scale i tup, with passives. Sorry, you will need to spend few $ for a 5k (4.7----5.6k) pot.
     
  10. studiot

    AAC Fanatic!

    Nov 9, 2007
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    I was hoping if I asked enough questions someone would recognise the thing and know what to do.

    Welcome
     
  11. adamj12b

    Thread Starter Member

    Mar 3, 2009
    15
    0
    Well, I guess I will have to find something else that will work for my application. Thanks guys for the help.

    -Adam
     
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