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design a linear thermistor

Discussion in 'General Electronics Discussion' started by Neks4, Jan 25, 2011.

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  1. Neks4

    Neks4

    3
    0
    Jan 25, 2011
    Please can anyone help me with the design of a thermistor tht will give me a linear reponse...
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
    2,780
    Jan 21, 2010
    Define linear.

    Is a platinum RTD close enough for you? How about a K type thermocouple?
     
  3. shrtrnd

    shrtrnd

    3,767
    487
    Jan 15, 2010
    *steve*'s right.
    Thermistor types are typically chosen for their relative 'linearity', WITHIN a specific temperature range.
    You need to know the temperature range you're looking at, and how accurate you
    want the circuit to be.
    Thermistors are not linear. They are chosen for their relative linearity within the characteristic
    curve of it's (operating) range.
     
    Last edited: Jan 25, 2011
  4. Neks4

    Neks4

    3
    0
    Jan 25, 2011
    shrtrnd,


    thank you, i know thermistors are not linear, i have a range of 20-70, i need to design a circuit, connecting ther thermistor to some component i dnt know now, to make my lnR vs 1/T(kelvin) graph linear.

    what i really want to know is how to go about designing this circuit.


    i willl be very grateful if u can show me how to design this circuit.. or model....



    i know abt the K-type thermocouple, but i need to design it myself. thank you

    Thermistor types are typically chosen for their relative 'linearity', WITHIN a specific temperature range.
    You need to know the temperature range you're looking at, and how accurate you
    want the circuit to be.
    Thermistors are not linear. They are chosen for their relative linearity within the characteristic
    curve of it's (operating) range
     
  5. shrtrnd

    shrtrnd

    3,767
    487
    Jan 15, 2010
    I'm not trying to be a putz about this:
    '20 to 70' , WHAT?
    The temperature matters
    I'm also a little confused about whether you already HAVE a thermistor selected, or if
    you're trying to design your circuit, and then select the thermistor you want.
    We know YOU know what you're trying to do.
    But we've only got what you tell US, about it, to work with.
     
  6. Neks4

    Neks4

    3
    0
    Jan 25, 2011
    20-70 degrees centigrade.

    i got a thermistor, bt dnt know the name, it's got a lil head, and 2 pins like a scissors.. or rather a plier
     
  7. shrtrnd

    shrtrnd

    3,767
    487
    Jan 15, 2010
    Alright, you've got a thermistor, you want to design a circuit for reading your thermistor. (Not design the thermistor itself).
    Check www.omega.com
    It's Omega Engineering, and they have good selection/application notes.
    I think that'll give you a better idea which direction to take in this project.
    They also have contact people for specific questions.
    Good luck.
     
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