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  • Help understanding ohmmeter reading

    This is probably a dumb question, but I can't tell what the reading means on my ohmmeter. I'm trying to read the resistance on the blue temp sensor, and I've read that it should be between 1450 to 3300 ohms at ambient temp.

    My ohmmeter gives me readings like "1.994" and "1.854" when on the 2k scale, and "1.96" and "1.90" on the 20k scale (at room temperature). I don't know what these numbers mean, relative to the expected "1450 to 3300".

    The reading drops rapidly if I plunge the sensor into a cup of hot water, so the resistance varies by temperature.

    Can someone help? It's a Sperry DM-350A, if that makes a difference. What do these numbers mean?

    Thanks!
    The day ain't over yet....

  • #2
    2K means the highest reading you can measure is 1,999 ohms. 20K means the highest resistance you can measure is 19,999 ohms.
    So 1.994 is 1,994 ohms, 1.854 is 1,854 ohms.
    On the 20K scale, 1.96 is 1,960 ohms 1.90 is 1,960 ohms.
    Basically, you're just changing the multiplier - 2K has 3 zeros, 20K has 4 zeros
    For the best accuracy, you use the lowest scale that gives you a reading.
    If you cool the sensor down till the resistance is over 1999 ohms and try to take a measurement on the 2K scale, the screen will go blank (or do something) and you'll have to change to the 20K scale to get a reading.

    HTH

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    • #3
      Originally posted by jimmyC View Post
      Basically, you're just changing the multiplier - 2K has 3 zeros, 20K has 4 zeros
      For the best accuracy, you use the lowest scale that gives you a reading.
      If you cool the sensor down till the resistance is over 1999 ohms and try to take a measurement on the 2K scale, the screen will go blank (or do something) and you'll have to change to the 20K scale to get a reading.
      HTH
      Thanks Jimmy! I was pretty sure it was something like that. My old multimeter had scales in multiples of 10, so it was somewhat easier (for me!) to understand.

      On this Sperry, the scale goes to "1." when it overflows.

      Bottom line is that it appears this sensor is within spec at room temp.
      The day ain't over yet....

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