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"Slinky" Primary / Sloped Archimedes Spiral Primary Equation


----------
From:  Dave Sharpe [SMTP:sccr4us-at-erols-dot-com]
Sent:  Saturday, August 15, 1998 8:41 PM
To:  Tesla List
Subject:  Re: "Slinky" Primary / Sloped Archimedes Spiral Primary Equation

Tesla List wrote:
> 
> ----------
> From:  Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
> Sent:  Friday, August 14, 1998 12:06 AM
> To:  Tesla List
> Subject:  Re: "Slinky" Primary / Sloped Archimedes Spiral Primary Equation
> 
> Tesla List wrote:
> >
> > ----------
> > From:  Dave Sharpe [SMTP:sccr4us-at-erols-dot-com]
> > Sent:  Wednesday, August 12, 1998 9:51 PM
> > To:  Chip Atkinson
> > Subject:  "Slinky" Primary / Sloped Archimedes Spiral Primary Equation
> >
> > Chip, ALL
> >
> > A while back, (before the detonation of my HD :^C ) I has saved a copy
> > of a post for a sloped "pancake" primary inductance and tubing length
> > based on coil ID, OD, spacing and included acute angle from horizontal
> > plane.  I've tried searching in archives without success.  If someone
> > could privide I would appreciate it greatly.  I'm contemplating building
> > a small (450VA/ 15kV,30mA NST) system using a sloped primary where
> > the HEIGHT (ie included length) is adjustable while running.  This
> > would allow primary tuning, coincidental with coupling increase or
> > decrease.  Any help appreciated
> >
> > Regards,
> >
> > DAVE SHARPE, TCBOR
> 
> Dave,
> 
> Hope this is what you're looking for. Included are Archimedes, helical,
> and inverse conical primaries. The helical and Archimedes forms are from
> Wheeler, and the inverse conical is a hybrid form that appropriately
> weights the vertical and horizontal components of Helical and Archimedes
> inductances.
> 
> All dimensions are in inches, and L is in microHenries. While the
> Inverse Conical calculation is a little "hairier" than the first two,
> it's relatively easy to calculate for any desired angle, especially if
> set up in a spreadsheet.
> ------------------------------------------------------------------------
> Case 1: Archimedes Spiral (Flat):
> 
>           Let R = Ave Radius
>               N = Number of Turns
>               w = Width of Winding
> 
>            |   R    |      N Turns
>       o o o o o o   |   o o o o o o
>       |    W    |   |
> 
>      L = (R^2)*(N^2)/(8*R+11*W)   (R^2 = R*R)
> 
> ------------------------------------------------------------------------
> 
> Case 2: Helical Primary:
> 
>                 |<- R ->|
>             --  o       |       o
>             |   o       |       o
>                 o       |       o
>             L   o       |       o  N Turns
>                 o       |       o
>             |   o       |       o
>             --  o       |       o
> 
>       L = R^2*N^2/(9*R+10*L)  (Vertical Helix)
> 
> ------------------------------------------------------------------------
> 
> Case 3: Inverse Conical Primary:
> 
> 
>                                     / \
>     --  o                          /    o
>      |   o                        /    o
>      |    o   N turns            /    o
>            o                 Z  /    o
>      h      o                  /    o   /
>              o                /    o   /
>      |        o              /    o   /  Angle = X
>      |         o              \  o   /
>     --          o               o    ------------
>                         |
>         |   w   |   R   |
>                         |
>             |<--  W  -->|
>                         ^
>                  Center | Line
> 
>           Z = Coil Width (hypotenuse length)
>           X = Angle of Cone
>           h = Z*sin(X)  Effective vertical Height
>           w = Z*cos(X)  Effective horizontal Width
>           W = R + w/2   Average horizontal Radius
> 
>      L1 = W^2*N^2/(9*W+10*h)  (Vertical Inductance Component)
> 
>      L2 = W^2*N^2/(8*W+11*w)  (Horizontal Inductance Component)
> 
>       L = SQRT[(L1*Sin(X))^2 + (L2*cos(X))^2]
> 
> ------------------------------------------------------------------------
> Safe coilin' to you, Dave! Hope to see you and Richard later this month!
> 
> -- Bert --

Bert, Chip, ALL

Thanks for the info, thats what I was looking for...

Unfortunately I won't be making the meeting this year, I've got
family commitments next weekend which prevent me from coming.  To
add insult to injury, I may be internationally travelling for work
during Richard's get together      >:^C ...

A very interesting website that I've stumbled into is:

www.abbsem-dot-com

ABB Semiconductors is now marketing their new IGCT and GCT
SS devices for high horsepower VSD, bus interties, etc.
Device voltages to 6.9kV, currents to 5kA and optically
isolated.  EXPENSIVE, but available.  Have in fact been
operated at FULL RATING at 400kHz 10 cycles.  And a SS spark
gap switch doesn't exist??  I wander....  Checkout the
technical papers, TRULY AMAZING technology.

Regards

DAVE SHARPE, TCBOR