Re: (Re) Wire Length (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 20 Dec 2006 20:53:00 -0600
From: Shaun Epp <scepp@xxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: (Re) Wire Length (fwd)

Lets try this again!, since the equation I pasted was an image and didn't 
get sent with the original email.
The common known equation for inductance of a spiral is as follows:

Spiral Coil Inductance:

L =       (NR)^2
      -----------------
           8R + 11W

L = inductance of coil in microhenrys (µH)
N = number of turns
R = radius of coil in inches (Measure from the center of the coil to the 
middle of the wire.)
H = height of coil in inches

see the link for a picture desription of the coil and measurements: 
http://tesla770.tripod.com/id5.html

Shaun Epp

----- Original Message ----- 
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, December 19, 2006 2:18 PM
Subject: (Re) Wire Length (fwd)


> Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Tue, 19 Dec 2006 05:05:06 -0500
> From: Jared Dwarshuis <jdwarshuis@xxxxxxxxx>
> To: Pupman <tesla@xxxxxxxxxx>
> Subject: (Re) Wire Length
>
> Hi: Bart
>
> I have not wound any flat secondary (yet). I am wondering if the 
> inductance
> can be roughly calculated as:
>
> L =   [4 pi x 10^ -7  x (wire length)sqrd] / [ 4 pi Radius ]
>
> They say that Tesla used wood boiled in linseed oil, I have not tried 
> this.
> If i were to do this (for reproduction purposes) my choice of wood would 
> be
> spruce or similar softwood. I say this because many hardwoods
> (especialy wood from tropical enviroments) have minerals in the grain that
> are likely to be somewhat conductive. ( teak is horrible, you can see 
> sparks
> when the carbide blade hits the mineral pockets)
>
> Yes racing sparks are fun to look at; but all that effort up in smoke!
> With some coils there is a race to get the coil tuned before it destroys
> itself ( part of the price you pay for leaving the beaten path I
> suppose.....)
>
> Seems like a flat coil would make a rather neat half wave. You could have 
> a
> skinny toroid capacitor around the outside. And a sphere or toroid in the
> center. With proper ballance you might get the crazy motion of a quarter
> wave coil, but restricted between points. ( and best of all; no ground to
> mess with!!)
>
> Sincerely: Jared Dwarshuis
>