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Digital potentiometer ?'s

Discussion in 'General Electronics Discussion' started by Chevyman2016, Apr 23, 2016.

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  1. Chevyman2016

    Chevyman2016

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    Apr 23, 2016
    I need to be able to take a 0-90 ohm potentiometer input and scale it to a 33-240 ohm output where 0=240 and 90=33, what I have is a 90 ohm fuel level sending unit in a project truck 0empty 90full and convert that inversely to operate the fuel gauge. The fuel gauge is looking for 33 ohm full tank and 240 ohm empty. I think this may be possible with a digital potentiometer but not an electronics guru. I mostly do home and industrial power and vehicular wiring. I'd be willing to buy something if someone can build it inexpensively.
     
  2. dorke

    dorke

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    Jun 20, 2015
    It would be easier if you could provide the voltages related to the resistances.
    Can you measure that?
    With that info a very simple "scaling " voltage amplifier can be designed.
     
  3. Chevyman2016

    Chevyman2016

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    Apr 23, 2016
    Ivwould assume 5 volt on my new digital dash. The sending unit will have no voltage on that side just the variable resistance the dash I purchased is from intellitronix it is the 5 gauge digital display but ibdo not have it yet just ordered it last night
     
  4. dorke

    dorke

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    Jun 20, 2015
    Please post a link to the systems datasheet.
     
  5. Chevyman2016

    Chevyman2016

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    Apr 23, 2016
    I have sent an email requesting this information I will post back here when I receive a reply thank you
     
  6. Kiwi

    Kiwi

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    Jan 28, 2013
    Are you sure that the fuel gauge on their 5 gauge dash is not programmable to suit your sender?
     
  7. Chevyman2016

    Chevyman2016

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    Apr 23, 2016
    It might be but the way it looked to me was only the 0-99% part was programmable when it comes in the mail I'll hook it up to another sender I have on my workbench and test it. But i do know the 33-240 ohm senders usually work backwards of the 0-90 sending units 0empty 90 full 240 empty 33full that was my worry matching ohms up and inverting the 0-90 to work with the gauges
     
  8. Kiwi

    Kiwi

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    Jan 28, 2013
    "Fuel gauge is programmable for Ford, GM, Chrysler, VDO and universal aftermarket senders."

    I would guess that the initial setup would be something along the lines of hold the sender at empty and then move to full. There might be a button or something on the back you push to do this. The PIC inside the gauge will then save these limits.

    The 0-99% for fuel level saves using a third digit on the readout to give 100%.
     
  9. Chevyman2016

    Chevyman2016

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    Apr 23, 2016
    I hope that is the case that would save a lot of people a lot of headache.
     
  10. Chevyman2016

    Chevyman2016

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    Apr 23, 2016
    Wow I mist have looked all day for information and just now found the instructions for the gauge set first try. It has dip switches to program the proper ohms to the gauges. Thanks everyone for your ideas sometimes I get a little ahead of myself trying to plan out projects.
     
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