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capacitance of this inductor

Discussion in 'Electronic Design' started by Gary Peek, Sep 15, 2006.

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  1. Gary Peek

    Gary Peek Guest

    I have found the following series of coils to be a dandy
    alternative to winding your own coil when playing around
    with FM wireless microphone projects:

    The data sheet does not suggest a capacitance value.
    Anybody care to take a guess? (It's not critical, I'm
    just wondering.)

    Gary Peek
    Industrologic, Inc.

  2. Can't you figure it out for yourself? its a simple resonant circuit.
    Subtract the minimum inductance for a given coil from the maximum, and
    divide it in half to allow for some tuning range, then use that value
    and the desired frequency to calculate the required capacitance.

    There are eight different coils and 100 US FM channels
    <> You don't really
    expect someone to give you all 800 answers, do you?

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  3. Gary Peek wrote...
    Those are fine, as far as they go, but it's not far, only
    to 0.465uH. That's a rather limited HF operating region.
    Taking the 0.465uH inductor, they don't give the SRF,
    which many inductor manufaturers provide, but they do
    test at 50MHz. So if we assume an SRF above 100MHz,
    that limits the coil's self-capacitance to 5.4pF.
  4. I think he wants the self-capacitance. Only the manufacture or a user
    would know that, and it SHOULD be on the data sheet.

    But if the coils are good to 500 MHz, the self-resonance must be higher
    than that, so, taking the maximum inductance, find the capacitor that
    resonates at 500 MHz. The self-capacitance must be less than that.
  5. Gary Peek

    Gary Peek Guest

    Thank you John, you indeed understand the question, and thank you
    Winfield, since you gave me the quick estimate I was interested in
    and how to find it. I too agree it should be on the data sheet.

    Gary Peek
  6. Guest

    Bit late maybe but for a bare wire single layer solenoid ...

    Coil capacitance = radius in centimetres.

    If wire is insulated or moulded in plastic then double the value.
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