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  1. #1
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    parasitic coil capacitance from frequency

    Sweeping a coil with generator measured a coils voltage peaking at ~30.7Mhz and dipping at ~14Mhz - its inductance is ~4mH.

    Does this mean its parasitic capacitance is 6.71 fempto farads?
    Last edited by Zak28; 13th July 2019 at 02:15.

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  2. #2
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    Re: parasitic coil capacitance from frequency

    Can't be answered without knowing the complete measurement circuit.



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    Re: parasitic coil capacitance from frequency

    Another way is to apply fast rising edge step voltage and measure the ringing.



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  4. #4
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    Re: parasitic coil capacitance from frequency

    Parasitic coil capacitance refers to parallel capacitance, I presume. Thus you are looking for the parallel resonance of the unloaded coil. The best approach for unloaded resonance measurement is a weakly coupled grid dip meter or an equivalent setup.

    The fact that your measurement shows two resonances makes clear that your setup isn't a simple LC parallel circuit but some kind of LCC or LLC circuit. And most likely parasitic parameters of the measurement setup are falsifying the original resonance frequency.



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