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Inductor question

Discussion in 'Electronic Basics' started by Jay, Jan 31, 2004.

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  1. Jay

    Jay Guest

    Hi everyone. I have a question about inductors I hope someone can help
    me with. It is for a physics lab and I am not too familiar with them.
    I had imagined that they would have two leads like a resistor. However
    I sent out for a variable inductor and received something that had
    five leads - two on one side and three on the other. It also had two
    larger ones on the side but I suspect they would be used for mounting
    on a board. My question is about the function of the five leads here -
    what exactly is what?

  2. A straight inductor does only have two leads. Your five lead device contains
    some combination of winding taps and coupled windings.

    Measure the resistance between the leads with an ohmmeter, you will find
    that some leads are connected by a low resistance, and by comparing the
    resistances you should be able to determine the order (the pair with the
    highest resistance between them are then ends of the winding, any other
    wires are taps connected to the middle parts of the winding).

    You may find that there are two separate windings, so that the resistance
    between wires belonging to different windings is nearly infinite. This means
    your inductor is also a transformer (since transformers are just coupled
    inductors). It's also possible that some pins on the device aren't connected
    to anything, or are connected to the case. Use your ohmmeter to figure this

    There should be a ferrite slug in the middle with screw taps in it, turn
    this with a non-ferrous screwdriver to adjust the inductance of the windings
    and/or the coupling between them.
  3. Jay

    Jay Guest

    Jacobe - thanks very much for the information!

    Take Care -
    - Jay
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