Help with the math


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  1. #1
    Join Date
    Mar 2011
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    Los Angeles, California
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    Question Help with the math

    Hi All!
    My brain seems to be in a thick fog these days, maybe it's the onset of oldtimes disease? Okay so I have a model that is 1:100 scale. The speed pressure sensor reads a maximum pressure of 2 psi. According to the Online conversion forum water speed = psi. This would tell me that the maximum speed for the sensor would be 200 mph. The output of the A/D gives 65472 as the reading for 2 psi. The sensor has a start point of 5824 for zero. How can I convert all this to a meaningful number to show the scale speed? Thanks to all.

    Ed

  2. #2
    Join Date
    May 2013
    Location
    australia
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    Default Re: Help with the math

    assuming your sensor is fairly linear
    count = 65472-5824 =59648
    divide that by 200mph =298.24 counts per mph

    so mph = (adc_count-5824)/298

  3. #3
    Join Date
    Nov 2003
    Location
    Greece
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    3,099

    Default Re: Help with the math

    And since no one can guarantee that adc_count would not go below 5824, I would add this:

    if adc_count<5824 then ad_count=5824 just before.

    Ioannis

  4. #4
    Join Date
    Jul 2014
    Location
    NingBo China
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    10

    Default Re: Help with the math

    5824 is Zero drift? if so,my calculation :

    actual flow(mph)/200(mph)=sensor display-5824/65472-5824
    actual flow (mph)=200(sensor display-5824)/59648
    Last edited by Bartchou; - 5th September 2014 at 07:17.

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