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Coil formula

Discussion in 'Electronic Design' started by Dirk Bruere at Neopax, Jan 30, 2005.

  1. Any got a pointer to the formula for inductance and field strength for a given
    current for a large dia air core coil? Dia>>length or winding thickness

    thanks
    Dirk

    The Consensus:-
    The political party for the new millenium
    http://www.theconsensus.org
     
  2. Clarence_A

    Clarence_A Guest

  3. Thanks, but I've already seen it.
    I was hoping for a 'finished' formula so I wouldn't have to spend a few hours
    messing around with stuff since I'll be juggling several other variables besides
    the obvious ones.
    Actually, a better version of the above is here:
    http://www.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html


    --
    Dirk

    The Consensus:-
    The political party for the new millenium
    http://www.theconsensus.org
     
  4. I read in sci.electronics.design that Dirk Bruere at Neopax
    Inductance = 1.6 uH per metre of turn length, for one turn, if the
    conductor diameter is much smaller than the coil diameter. For more
    turns, if closely-coupled, multiply by the square of the number of
    turns.

    At what point do you want to know the field strength? At an arbitrary
    point, it involves elliptic functions, but some points are degenerate
    and give simple results.
     
  5. John Larkin

    John Larkin Guest



    ====================================================

    ' INDUCTANCE OF CIRCULAR RING

    ' REF DATA P 6-9

    CLS

    TOP: INPUT "RING RADIUS, INCHES ", A
    IF A = 0 THEN GOTO EXX

    PRINT

    INPUT "WIRE DIA, INCHES ", D
    IF D = 0 THEN GOTO EXX

    PRINT

    L = (A / 100) * (7.353 * LOG(16 * A / D) / LOG(10) - 6.386)

    PRINT USING "L = #####.##### uH"; L

    PRINT
    PRINT
    GOTO TOP

    EXX: END

    ================================================================

    ' PROGRAM : MAGFIELD.BAS
    ' BY : JENNIFER HO
    ' HIGHLAND TECNHOLOGY, INC.
    ' FEBRUARY 2, 1995

    DEFDBL A-Z


    CLS

    PRINT "GIVEN A CIRCULAR LOOP OF RADIUS (R) CARRYING CURRENT
    (I),"
    PRINT "THIS PROGRAM CALCULATES THE MAGNETIC FIELD (B) AT ALL"
    PRINT "POINTS ON THE AXIS OF THIS LOOP, WHICH WE TAKE TO BE
    THE"
    PRINT "Z AXIS, WITH Z=0 AT THE LOOP CENTER."
    PRINT
    PRINT

    INPUT "ENTER LOOP RADIUS (R) in Meters : ", R
    IF R = 0 THEN GOTO EXXON

    INPUT "ENTER LOOP CURRENT (I) in Amperes : ", I

    INPUT "ENTER THE DISTANCE (Z) ALONG THE AXIS in Meters : ", Z

    'Uo IS IN THE UNIT OF "GAUSS METER / AMPERE".

    Uo = 12.57 * 10 ^ -3

    B = (Uo * I * R ^ 2) / (2 * SQR((Z ^ 2 + R ^ 2) ^ 3))


    PRINT
    PRINT " ggg mmmuuunnn"
    PRINT USING "FIELD (B) in Gauss IS : ###.#########"; B

    EXXON:
    END


    =============================================================

    ' PROGRAM : MAGFIELD.BAS
    ' BY : JENNIFER HO
    ' HIGHLAND TECNHOLOGY, INC.
    ' FEBRUARY 2, 1995

    DEFDBL A-Z


    CLS

    PRINT "GIVEN A CIRCULAR LOOP OF RADIUS (R) CARRYING CURRENT
    (I),"
    PRINT "THIS PROGRAM CALCULATES THE MAGNETIC FIELD (B) AT ALL"
    PRINT "POINTS ON THE AXIS OF THIS LOOP, WHICH WE TAKE TO BE
    THE"
    PRINT "Z AXIS, WITH Z=0 AT THE LOOP CENTER."
    PRINT
    PRINT

    INPUT "ENTER LOOP RADIUS (R) in Meters : ", R
    IF R = 0 THEN GOTO EXXON

    INPUT "ENTER LOOP CURRENT (I) in Amperes : ", I

    INPUT "ENTER THE DISTANCE (Z) ALONG THE AXIS in Meters : ", Z

    'Uo IS IN THE UNIT OF "GAUSS METER / AMPERE".

    Uo = 12.57 * 10 ^ -3

    B = (Uo * I * R ^ 2) / (2 * SQR((Z ^ 2 + R ^ 2) ^ 3))


    PRINT
    PRINT " ggg mmmuuunnn"
    PRINT USING "FIELD (B) in Gauss IS : ###.#########"; B

    EXXON:
    END


    ====================================


    John
     
  6. John Larkin

    John Larkin Guest

    Oops, Jennifer's prog got pasted twice.

    John
     
  7. Genome

    Genome Guest

    " Thanks, but I've already seen it.

    I was hoping for a 'finished' formula.

    You know, that one with the sum that don't include that there fancy math and
    references to french people.

    Just so I wouldn't have to spend a few hours fucking around with the locals.

    I'll be juggling several other variables besides the obvious ones."
     
  8. John Larkin

    John Larkin Guest

    As the conductor diameter trends towards zero, the inductance becomes
    infinite.

    John
     
  9. How accurate is that?
    Given, for example a coil with one metre dia and (say) 100 turns of #24?
    Well, I suppose the centre might be a good starting point.
    Typical coil dia would be around one metre.
    Also two metres from centre in the plane of the coil.

    --
    Dirk

    The Consensus:-
    The political party for the new millenium
    http://www.theconsensus.org
     
  10. Sorry I'm not helping, except that, what is a millenium?
     
  11. Thanks.
    Interesting as I am going to write a Java applet to do something similar.

    --
    Dirk

    The Consensus:-
    The political party for the new millenium
    http://www.theconsensus.org
     
  12. True, its a real pain fucking around with the locals, or at least some of them.

    --
    Dirk

    The Consensus:-
    The political party for the new millenium
    http://www.theconsensus.org
     
  13. Its like 'millennium' but shorter.
    A bit like 'It's' without an apostrophe.

    --
    Dirk

    The Consensus:-
    The political party for the new millenium
    http://www.theconsensus.org
     
  14. John Larkin

    John Larkin Guest



    It's 1/1000 of a lenium.


    John
     
  15. agreed, but what is a lenium?
    I know about lenniums.
     
  16. Genome

    Genome Guest

    Uo is 4piE-7.

    That's in SI units.

    Which have been established as being established by the French, I think.

    I assume that SouthPark might have something to say about this because they
    take the piss out off Scotts speaking french people and had war with the
    Americans, who are basically Irish......

    What the **** you are doing calling your company Highland Technology for?
    (and making me take care over the spelling) is another thing, perhaps you
    are denying your heritage.

    Speff's Canadian (and he'd better not be fucking about with that one if I'm
    not going to get overly disillusioned about the general state of things)

    The Aylward appears to have claimed to be a nigger, but he's an export.....
    so he's not an Indian. It's not that they write better software they are
    just cheaper.... Sorry I read that Kevin has embedded something so deep in
    his code that he would rather not be arsed getting it out again.


    Which, taking Jennifer's sums, should be 12.57E-7.

    Now, I know you Americans have had some problem in the past with the odd
    factor of something like 4E8 or the odd erg slug foot cubit.

    But!!!!!!!!! You now come along with your Power Penis.

    DisFuckingGusting. Wot you want is one of these.

    unit roundedit;

    interface

    uses
    Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
    Grids, DBGrids, Db, DBTables, ToolWin, ComCtrls, Menus, DBActns,
    ActnList, ImgList, ExtCtrls, DBCtrls, Math, Spin, StdCtrls, FileCtrl;

    type
    TRoundWireForm = class(TForm)
    DataSource1: TDataSource;
    Table1: TTable;
    ToolBar1: TToolBar;
    ImageList1: TImageList;
    ActionList1: TActionList;
    DataSetFirst1: TDataSetFirst;
    DataSetLast1: TDataSetLast;
    DataSetNext1: TDataSetNext;
    DataSetPrior1: TDataSetPrior;
    ToolButton1: TToolButton;
    ToolButton2: TToolButton;
    ToolButton3: TToolButton;
    ToolButton4: TToolButton;
    ToolButton5: TToolButton;
    ToolButton6: TToolButton;
    DataSetInsert1: TDataSetInsert;
    ToolButton7: TToolButton;
    DataSetCancel1: TDataSetCancel;
    DataSetPost1: TDataSetPost;
    ToolButton8: TToolButton;
    ToolButton9: TToolButton;
    DataSetDelete1: TDataSetDelete;
    DBGrid1: TDBGrid;
    Table1Standard: TStringField;
    Table1CuDiamm: TFloatField;
    Table1DiaLmm: TFloatField;
    Table1DiaSmm: TFloatField;
    Table1DiaHmm: TFloatField;
    Table1DiaTmm: TFloatField;
    MainMenu1: TMainMenu;
    File1: TMenuItem;
    Exit1: TMenuItem;
    GroupBox1: TGroupBox;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Flabel: TLabel;
    Llabel: TLabel;
    Tlabel: TLabel;
    FUpDown: TUpDown;
    LUpDown: TUpDown;
    TUpDown: TUpDown;
    LightRadio: TRadioButton;
    SingleRadio: TRadioButton;
    HeavyRadio: TRadioButton;
    TripleRadio: TRadioButton;
    GroupBox2: TGroupBox;
    Label4: TLabel;
    Label5: TLabel;
    Label6: TLabel;
    RdcLabel: TLabel;
    RacLabel: TLabel;
    RraLabel: TLabel;
    Label7: TLabel;
    Label8: TLabel;
    Table1Guage: TFloatField;
    procedure Exit1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure DataSource1DataChange(Sender: TObject; Field: TField);
    procedure FUpDownClick(Sender: TObject; Button: TUDBtnType);
    procedure LUpDownClick(Sender: TObject; Button: TUDBtnType);
    procedure TUpDownClick(Sender: TObject; Button: TUDBtnType);
    procedure LightRadioClick(Sender: TObject);
    procedure SingleRadioClick(Sender: TObject);
    procedure HeavyRadioClick(Sender: TObject);
    procedure TripleRadioClick(Sender: TObject);
    private
    { Private declarations }
    procedure Recalc;
    public
    { Public declarations }
    end;

    var
    RoundWireForm: TRoundWireForm;

    implementation

    {$R *.DFM}

    procedure TRoundWireForm.Recalc;
    var
    Resistivity : double;
    SkinDepth : double;
    CuDiametre : double;
    InsDiametre : double;
    Height : double;
    LayFact : double;
    Quality : double;
    Mac : double;
    Dac : double;
    Fratio : double;
    DCResistance : double;
    ACResistance : double;
    begin
    If LightRadio.Checked=True then
    InsDiametre := Table1.FieldByName('Dia (L) / mm').AsFloat/1000;
    If SingleRadio.Checked=True then
    InsDiametre := Table1.FieldByName('Dia (S) / mm').AsFloat/1000;
    If HeavyRadio.Checked=True then
    InsDiametre := Table1.FieldByName('Dia (H) / mm').AsFloat/1000;
    If TripleRadio.Checked=True then
    InsDiametre := Table1.FieldByName('Dia (T) / mm').AsFloat/1000;
    CuDiametre := Table1.FieldByName('Cu Dia / mm').AsFloat/1000;
    If (InsDiametre>0) and (CuDiametre>0) then
    begin
    Resistivity := 1.72417E-8*(1+0.00393*(TUpDown.Position-20));
    SkinDepth := Sqrt(Resistivity/(pi*4*pi*1E-7*1000*FUpDown.Position));
    Height := CuDiametre*Sqrt(pi/4);
    LayFact := CuDiametre/InsDiametre;
    Quality := Sqrt(LayFact)*Height/SkinDepth;
    Mac :=
    Quality*(sinh(2*Quality)+sin(2*Quality))/(cosh(2*Quality)-cos(2*Quality));
    Dac := 2*Quality*(sinh(Quality)-sin(Quality))/(cosh(Quality)+cos(Quality));
    Fratio := Mac+Dac*(Sqr(LUpDown.Position)-1)/3;
    DCResistance := Resistivity/(Sqr(CuDiametre/2)*pi);
    ACResistance := Fratio*DCResistance;
    RdcLabel.Caption := FloatToStrf(DCResistance,ffGeneral,5,0);
    RacLabel.Caption := FloatToStrf(ACResistance,ffGeneral,5,0);
    RraLabel.Caption := FloatToStrf(Fratio,ffGeneral,5,0);
    end
    else
    begin
    RdcLabel.Caption := 'Not Available';
    RacLabel.Caption := 'Not Available';
    RraLabel.Caption := 'Not Available';
    end;
    end;

    procedure TRoundWireForm.Exit1Click(Sender: TObject);
    begin
    close;
    end;

    procedure TRoundWireForm.DataSource1DataChange(Sender: TObject;Field:
    TField);
    begin
    Recalc;
    end;

    procedure TRoundWireForm.FUpDownClick(Sender: TObject;
    Button: TUDBtnType);
    begin
    Flabel.Caption := IntToStr(FUpDown.Position);
    Recalc;
    end;

    procedure TRoundWireForm.LUpDownClick(Sender: TObject;
    Button: TUDBtnType);
    begin
    Llabel.Caption := IntToStr(LUpDown.Position);
    Recalc;
    end;

    procedure TRoundWireForm.TUpDownClick(Sender: TObject;
    Button: TUDBtnType);
    begin
    Tlabel.Caption := IntToStr(TUpDown.Position);
    Recalc;
    end;

    procedure TRoundWireForm.LightRadioClick(Sender: TObject);
    begin
    Recalc;
    end;

    procedure TRoundWireForm.SingleRadioClick(Sender: TObject);
    begin
    Recalc;
    end;

    procedure TRoundWireForm.HeavyRadioClick(Sender: TObject);
    begin
    Recalc;
    end;

    procedure TRoundWireForm.TripleRadioClick(Sender: TObject);
    begin
    Recalc;
    end;

    procedure TRoundWireForm.FormCreate(Sender: TObject);
    begin
    Label1.Caption := 'Frequency KHz';
    Label2.Caption := 'Layers';
    Label3.Caption := 'Temperature C';
    Label4.Caption := 'DC Resistance/m';
    Label5.Caption := 'AC Resistance/m';
    Label6.Caption := 'Rac/Rdc Ratio';
    Flabel.Caption := IntToStr(FUpDown.Position);
    Llabel.Caption := IntToStr(LUpDown.Position);
    Tlabel.Caption := IntToStr(TUpDown.Position);
    HeavyRadio.Checked := True;
    end;
    end.
     
  17. Genome

    Genome Guest

    In case you missed it we had a New One.

    It's like it's dead special...

    Like you think a Millenium has something to do with a Million things.

    It was probably something invented by Greeks and adopted by the Romans so it
    got divided by a thousand, you know, like towards the end.

    Like in modern times.... third fourth and fifth reich. Cherry blossoms of
    the doodad.

    Yup, this ones going to last a 'mill' oo0ps thousand years. Oh bugger we got
    fucked over, shit.





    Hey! folks. It's a new Millenium.......

    And, just in case your thinking we're going to tell you that we sure aint
    going to **** you over again... just don't forget that it's all worth 9.99
    in the new currency.

    DNA
     
  18. LENIUM ES is a binary azeotrope of n-Propyl Bromide (nPB) and
    isopropanol expressly formulated to remove both polar and non-polar
    soils from circuit assemblies and components.

    http://www.petroferm.com/PTF-053/clean/eprod_len_content.html


    Best regards,
    Spehro Pefhany
     
  19. John Larkin

    John Larkin Guest

    Irish, German, dark rumors of a trace of French and possibly even a
    bit of converted Jew somewhere.

    I used to live on Highland Avenue and decided to incorporate and my
    expensive lawyer called me and asked for the company name to file the
    papers, so I said you-know-what. Never paid him, come to think of it.

    Our company logo depicts the view looking at Mount Tamalpias as seen
    from the toll plaza of the Bay Bridge. The moon thing is Artistic
    License, of course.

    If you want the field in Tesla, which she apparently didn't.


    John
     
  20. Genome

    Genome Guest

    Gauss.....

    Just like a Texan.

    DNA
     
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