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Building lt spice transformer / help!

Discussion in 'General Electronics Chat' started by killivolt, Oct 6, 2013.

  1. killivolt

    killivolt Well-Known Member

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    I can't do the Math or anything. It's one of the last things on my LT Spice Schematic.

    Edit: Oh, and if you could go through the steps, I'm not sure if the Data will provide it all or what, I'm confused about the hole process.

    Data Sheet of the Ferrite Core.

    http://www.epcos.com/inf/80/db/fer_07/r_25.pdf

    Here is the Schematic I have pulled off some of the values off the data sheet and put them on the schematic. I could sure use someone who could get this thing put together, maybe after I have a year or so practicing my maths I might have a go at it. But not at the moment.
     

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    Last edited: Oct 6, 2013
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Not quite sure what you're after, but to sim a transformer just place two inductors L1, L2 on the sheet and a command 'K1 L1 L2 1'. The inductor ratio is the square of the turns ratio.
     
  3. killivolt

    killivolt Well-Known Member

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    In this case I have 4 wires 14 turns so in order to get L "u" the square of 14 is 196u correct ?
     
  4. dave

    Dave New Member

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  5. killivolt

    killivolt Well-Known Member

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    Sure:

    I don't have a DC LCR meter, I have a DM,

    So, I'm just measuring resistance? At a Factor of 2 or higher correct?

    This is where I go, what the heck are they talking about?

    Heck, I have to find a DC LCR meter first.

    Thanks, good knowing you.

    Sorry for the sarcasim but, I'm so lost?
     
  6. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    I am confused.
    Are you building the transformer in spice or in real life?
     
  7. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Sorry, I don't understand that. What is 'u'? In Spice you specify the inductance of L1 and L2. If, for example, you specify L1=16mH and L2=1mH that corresponds to a L1:L2 turns ratio of 4:1
     
  8. killivolt

    killivolt Well-Known Member

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    Post #4 is from the help file in Spice, I don't have an LCR meter however I do have the Core Data sheet and # of turns and voltages, still beyond that I'm confused how it all fits together.

    Ron, I'm building this to find out if the circuit will function or not. I have already wound the Transformer.
     
  9. ChrisP58

    ChrisP58 Well-Known Member

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    To get the inductance of a coil, you take the Al value for the core from the datasheet and multiply that by the square of the turns.
     
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  10. killivolt

    killivolt Well-Known Member

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    I don't have any idea of L1 or L2 mH, I know that the core is at 4620 nH? How can I without an LCR meter ( only using) the Data sheet and the known V, #windings, permeability N30 at 25%, and Magnetic Characteristics from the Data sheet complete input needed for the Transformer in LT Spice?
     
  11. killivolt

    killivolt Well-Known Member

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    Finally.

    Thank you, ChrisP58

    You guy's are killing me, but I like it:)

    kv
     
  12. killivolt

    killivolt Well-Known Member

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    You guy's in the UK are funny, I don't like it, but your still funny, having fun at my expense.

    I know you will deny it, I've been there done that, haha.

    I still like you and enjoy reading your post's. I'm not sure I would have even been seen, had you not post.

    kv
     
  13. killivolt

    killivolt Well-Known Member

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    Wow, so 14 squared 196 and the square root 14 is 3.74

    196 x 4620 = 905520 or 3.74 = 17279 now I need the series resistance and Parallel Resistance and figure K, L1, L2, L3, L4, ()

    Which is it sqroot or squared?
     
  14. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    u in LTSpice is the abbreviation for 1e-6, just like m is for 1e-3 and n is for 1e-9. If you want 1e6, you have to write it as Meg or meg.

    The inductance of an inductor could be 0.0000013 or 1.3e-6 or 1.3u or 1.3uH (in the last case, the H is actually ignored)

    As to your other questions, look at this
     
    Last edited: Oct 6, 2013
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  15. killivolt

    killivolt Well-Known Member

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    Mike, sorry. That was way over my head, how do I deal with post #12 and talk like I'm 13 years old. When I edit the coil in LT Spice I need the values of

    Inductance [H]

    Series Resistance

    Parellel Resistance

    How do I aquire those. I'm flayling here and not landing on anything?
     
  16. ChrisP58

    ChrisP58 Well-Known Member

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    Your core has an Al value of 4620nH

    14 turns ^2 = 196

    196 * 4620^-9 = ~900uHy for each of your 4 windings.

    Add a spice directive (like alec_t said in post #2) of "K1 L1 L2 L3 L4 .995"

    The number at the end is the coupling efficiency. 1 implies 100%. A more practical value would be .99 to .995

    If you have more than one transformer in a circuit you would have more K directives.
    K2 L5 L6 .995
    K3 L7 L8 L9 .995
    etc.

    Series resistance is the DC resistance of the winding. It's not critical for your transformer, but put in 10 milliOhms as a rough estimate. Leave parallel resistance open.
     
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  17. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Follow the link in post 13. It tells you how to calculate the approximate inductance of your winding. For starters in LTSpice assume the series resistance of a winding is the same as you would measure with an Ohmmeter, Ignore Parallel resistance for now.
     
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  18. killivolt

    killivolt Well-Known Member

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    Thank you both.

    You are going to make this a good Christmas for my friends. I plan to build 2 of these Plasma Speakers and give them for Christmas.

    Thank you so, much.

    kv

    Edit: Only if I can make this darn circuit, work.
     
  19. killivolt

    killivolt Well-Known Member

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    Right now I'm not worried at all about the HV winding.

    Thanks again.
    kv
     
  20. killivolt

    killivolt Well-Known Member

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    I'll get back to you on it, once I have completed it, for correction.

    Chris, on the Transformer I wound, will I want to tie 2 and 3 or would I tie 2 and 4?


    kv
     
  21. ChrisP58

    ChrisP58 Well-Known Member

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    ?? I'm not sure what you mean by 2, 3 and 4.
     

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