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Why do the outputs of LDC1000 take a long time to be stable? What factors cause this result? Emergent question, Thanks!

Peng Zhuang
Prodigy 110 points
Other Parts Discussed in Thread: LDC1000EVM

Hello,

These is problem in my studies.

I have put a LC sensor into the magnificated field generated by the LC circut connected to LDC1000. And the output of LDC1000 is as the picture, the proximity data increased until to a stable data. I have tried several times, all results are the same. I don't know how to explain the result and what cause the phenomenon. 
If it is related to LDC1000, Hope someone can help me, Thanks.

 

 

  • 0
    TI__Genius 9300 points
    Hello,

    Sorry, it is not clear from your description what is going on.
    Do you have two LDC1000 and 2 sensors, and you place one next to the other?
    Or one sensor? Then what is generating magnetic field?
  • 0 in reply to Evgeny Fomin
    Prodigy 110 points

    Not two LDC1000, there's  two LC circuits, one from the LDC1000EVM connected to LDC1000 directly, the other one is made by myself.

    Right, I put one next to the other, and coupling distance is a constant. And result shows that after putting one to another, It takes a long time

    to be almost a stable value. So, is it related to LDC1000? How to explain the phenomenon?

    PS: the long time is about 4~6 hours.

  • 0 in reply to Peng Zhuang
    TI__Genius 9300 points

    ok, it's getting clearer.

    What is the purpose of the LC tank that you built yourself?

    What are L and C values? Is it connected anywhere, or just an LC oscillator?

  • 0 in reply to Evgeny Fomin
    Prodigy 110 points

    Thanks for help.

     

    The LC tank is just a signle LC oscillator, it connects nothing.

     

    Actually, what we think is to change the C to be a capacitive sensor, it can be a temperature sensor, a pressure sensor or some other capacitive sensor.

     

    but the result what we test is not so stable when the C is just a capacitor(as the figure shows). So, we don't know if the phenomenon is related to the performance of LDC1000, or it is ourselves faults.

     

    By the way, could you tell me how does LDC1000 mearsure the equivalent impendence and inductance? by impulse or some other ways. Thanks.

    If there's some paper or patent to answer this question, could you please sent it to me, thanks. My email is : pengz@hust.edu.cn

     

  • 0 in reply to Peng Zhuang
    TI__Genius 9300 points

    So, if LC tank is not connected to anything, why do you have it there at all?

    Yes, you could utilize LDC to measure changing capacitance.

    As you mentioned, it will be sensitive to temperature variations, and perhaps this is what you observe in your experiments, as you run the AC