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sense small inductive changes from a coil, and use it as a sensor — Parallax Forums

sense small inductive changes from a coil, and use it as a sensor

KatyBriKatyBri Posts: 171
edited 2006-12-12 04:14 in BASIC Stamp
I was looking at the Propeller object code site and noticed a contribution by Beau Schwabe (Parallax)·-· "sense small inductive changes from a coil, and use it as a sensor".

I would like to do this with a BS2. Has anyone done this with a BS2? Beau, can you modify your Propeller code to work with a BS2?

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,559
    edited 2006-12-11 04:50
    KatyBri

    There are a few ways to sense small inductive changes... It would help if I can get a better feel as to what your exact goal is, before I make a suggestion.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • terahertzterahertz Posts: 55
    edited 2006-12-11 04:56
    If the changes in the coil values change slowly, you could probably use the RCTIME command. Hold the R and C values constant and put the coil in parallel with the C. Find a correlation between the RCTIME value and the coil value. Use this in an IF statement?
  • KatyBriKatyBri Posts: 171
    edited 2006-12-12 03:26
    Beau, I'm interested in sensing current flowing through a 120VAC power cord. I'm not really interesting in knowing how much current is flowing throught the cord, only that some current is flowing.
  • Beau SchwabeBeau Schwabe Posts: 6,559
    edited 2006-12-12 04:14
    KatyBri,

    In that case, I'm afraid the inductor application you mention will not work the way you want.
    It is based on resonate frequency response characteristics of a coil with the proximity of a metal object, and will not work for measuring current.

    When measuring current flowing through a 120VAC power cord you must take certain safety precautions into consideration.
    Off the top of my head, a solution is beyond my scope at the moment, simply because I don't have the experience with 120VAC to provide a safe solution.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
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