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LTSpice: how to add a transformer?

Discussion in 'Electronic Design' started by Michael, Sep 19, 2007.

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  1. Michael

    Michael Guest

    Hi there - I'm trying to add a transformer to a LTSpice schematic. Can
    anybody give me any suggestions as to how to go about doing this? I
    can't find them anywhere! I remember in one circuit simulation program
    I used years ago I had to couple two inductors to create a
    transformer, but I can't even find such an option in the inductor


  2. Tom Bruhns

    Tom Bruhns Guest

    You can just place two inductances and something like "K1 L1 L2
    0.999" (text) next to them (or anywhere on the schematic, it's more
    readable if it's close to the inductors involved). There are more
    complicated models, including capacitance and resistance, of course,
    and you can also create one using sources to emulate the coupling.

    You should find at least a couple examples of transformers in the
    examples/educational directory under LTSpice: transformer.asc and

    You'd do well to join the Yahoo group for LTSpice, where you will find
    examples of transformers, discussions about transformer models, and
    lots of helpful folk.

  3. Joel Kolstad

    Joel Kolstad Guest

    You add two inductors and then add a SPICE directive (Edit->SPICE directive)
    along the lines of, "K1 L1 L2 0.99" which says L1 and L2 make up a transformer
    with a coupling coefficient of 0.99. (And in case you don't recall: The turns
    ratio goes with the square root of inductance -- if L1 is 1mH and L2 is 4mH,
    L1 has "x" turns and L2 has "2x" turns.)

    See the example: c:\program
    files\ltc\swcadiii\examples\educational\transformer.asc. For a three-winding
    transformer, there's transformer2.asc.

  4. Genome

    Genome Guest

    For blither.... ouch...

    For schematics

    For symbols.

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