Electronics How to linearize a thermistor?

Discussion in 'Modding' started by egweimai, 26 Oct 2004.

  1. egweimai

    egweimai What's a Dremel?

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    Hi.

    I would like to know how to linearize a thermistor. I want to use it to measure a wide of temperatures from 0 degrees C to 70 degrees C. Is there any IC? I don't care for the cost


    Thank you in advance
     
    egweimai, 26 Oct 2004
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  2. star882

    star882 What's a Dremel?

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    Code and a PIC.
     
    star882, 26 Oct 2004
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  3. ConKbot of Doom

    ConKbot of Doom Minimodder

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    now I'm sure he could do that without a PIC. I'd bet maxim has something you can hook the thermistor to that will give you a digital output, from which you can hook a DAC or a digi-pot and get a linear output.
     
    ConKbot of Doom, 26 Oct 2004
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  4. theshadow27

    theshadow27 What's a Dremel?

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    or you could get a linar analouge thermistor chip :duh:
     
    theshadow27, 26 Oct 2004
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  5. egweimai

    egweimai What's a Dremel?

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    I don't think that there are linear thermistors.
    I will linearize it programming in Visual Basic.

    Now another question. How can I calibrate a thermistor? I have a very accurate thermometer (0.001C). So I can measure the resistance for a lot of temperatures. I prefere to make the calibration in visual basic.

    Thank you in advance...


    Christos
     
    egweimai, 26 Oct 2004
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  6. cpemma

    cpemma Ecky thump

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    Easy option is to use a different type of sensor such as LM35Dz or LM335Z, which give a linear voltage with temperature. One snag is, they're both in TO92 cases, so more bulky than most thermistors.

    There is an equation relating thermistor resistance against temperature, but unless you plot the curve using your 'very accurate thermometer' as a reference and calculate an actual Beta for the thermistor and temperature range you want, results won't be all that accurate.
     
    cpemma, 26 Oct 2004
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