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Flexiforce

A.C. fishingA.C. fishing Posts: 262
edited 2006-07-11 03:57 in General Discussion
How could I make the flexiforce 1.6 lbs pressure sensor more sensitive?

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Somebody said...
-Never Underestimate the power of human stupidity.
·

Comments

  • steve_bsteve_b Posts: 1,563
    edited 2006-07-09 03:40
    Are you using the 'recommended' drive circuit?

    you can change the 'excitation' voltage (drive voltage) and the feedback resistors....can't quite remember the circuit so I couldn't say which way you should go!

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    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-07-09 05:48
    A.C. fishing,
    ·
    There are several ways to read this type of sensor.· When·Flexiforce·was just using the name
    Tekscan, the "preferred" circuit used a Schmitt trigger type of oscillator to read the sensor.
    Not that one is any better than the other, it depends more on your application, but you might
    give it a try.
    ·
    See the bottom of this datasheet for an example using the 74xx14 in a relaxation oscillator.
    Use the COUNT command to determine the·Flexiforce sensor value.·
    http://www.ortodoxism.ro/datasheets/philips/74HC_HCT14_CNV_2.pdf
    ·
    ·

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • A.C. fishingA.C. fishing Posts: 262
    edited 2006-07-09 15:54
    I was using the code and schematic given by the example in the documentation with the sensor.
    thanks Beau.

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    Somebody said...
    -Never Underestimate the power of human stupidity.
    ·
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-07-09 17:15
    Are you saying using the default code and schematic that it doesn't register anything until 1.6 lbs.?



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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • A.C. fishingA.C. fishing Posts: 262
    edited 2006-07-09 21:36
    It would seem so.

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    Somebody said...
    -Never Underestimate the power of human stupidity.
    ·
  • A.C. fishingA.C. fishing Posts: 262
    edited 2006-07-09 22:40
    I would like the sensor to react to a small pressure, just air pumped threw a tube to the sensor, and let out. How could I detect this?

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    Somebody said...
    -Never Underestimate the power of human stupidity.
    ·
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-07-10 04:19
    Seems like this might not be the right sensor for your application. Are you trying to measure the air
    pressure within the tube, or are you simply "blowing" on the sensor trying to get some sort of thrust
    reading?

    Just a thought.... Have you tried biasing the sensor with 1.6 lbs?

    Another thought.... since these sensors are likely to produce a reading when you "bend" them, would a
    configuration that does just that to the sensor be applicable for detecting·blown-air as you indicate?



    Perhaps if we had more information about your desired goal we can be of more assistance.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.

    Post Edited (Beau Schwabe (Parallax)) : 7/10/2006 4:24:51 AM GMT
  • A.C. fishingA.C. fishing Posts: 262
    edited 2006-07-10 20:59
    I'm trying to measure the pressure the air is putting on the sensor.

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    Somebody said...
    -Never Underestimate the power of human stupidity.
    ·
  • steve_bsteve_b Posts: 1,563
    edited 2006-07-11 03:57
    So you want to measure blowing air? How is the air acting on the sensor....do you have a large wind vane that is being pushed against it? Are you aiming the sensor in to the wind source?

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
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