Re: Wire Length (fwd)

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Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sat, 23 Dec 2006 09:28:03 -0700
From: Gary Peterson <g.peterson@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Wire Length (fwd)

> From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>

> I've been building another flat coil this last month.  It's
> sort of a Tesla duplicate, but scaled down . . . The
> primary will be flat copper ribbon around the perimeter
> of the secondary. . . .

> You may note that coupling is near 0.4, which is much
> higher than a classic helical coil.  This is solely based
> on a coilers instinct for this particular geometry.
> Bart

While I realize you probably already have this, here is Tesla's own 
description of the original oscillator, including the primary.

    "I have here a cut from the Electrical Review of October 26, 1898, in 
which there is shown in the background a flat spiral coil which I have 
marked A, and which is the coil in question.  There is a frame made of wood, 
which I have marked F, and which in reality is 8 by 8 feet, as before 
stated, and upon which there are wound, upon notched supports, about 50 
turns of well insulated cable No. 8.  The end of the coil, which is on the 
outer side of the spiral, was usually connected to the ground, and the end 
in the center to the insulated conductor of capacity, not shown in the cut. 
The coil is easily recognizable in the figure, presenting, as it does, the 
appearance of a spider web.  B is a coil supported on an insulated stand in 
front. . . . The primary is not shown here, being behind the frame. To 
excite the apparatus I used condensers which were charged from the 50 
kilovolt transformer and discharged in rapid succession through the primary. 
The transformer is not visible. [Nikola Tesla  Guided Weapons & Computer 
Technology, Leland I. Anderson, Twenty First Century Books, 1998, pp. 
12-13.]

    "This picture shows, or is a general view of, a part of my laboratory at 
46 East Houston Street, New York City, and shows several apparata which I 
have used in practicing this invention, and to which I have referred.  The 
spiral coil before described wound on a square 8 by 8 feet, made of wood, is 
shown in the background.  Looking at it, to the left will be seen a square 
frame of wood in which there were contained two turns of heavy cable, which 
I could connect either in series or multiple arc.  Those primaries, or 
respectively primary, were used when I desired to obtain two oscillations in 
the manner explained in my answer to question 16.  The spiral coil could be 
approached more or less to the frame, being placed on rollers for 
convenience, and thus I would graduate the mutual induction so that two 
oscillations resulted; one, considerably quicker, during the time interval 
when the primary or exciting circuit was closed, and another, slower one, 
during the interval when the primary was opened by the make-and-break disk, 
but both following each other in rapid succession so as to be practically 
simultaneous as far as the operation of the receiver is concerned.  Farther 
to the left may be observed some condensers which I used in addition to 
those already described.  In front of the picture will be seen the receiving 
apparatus in the form of a table which had two circuits, the terminals of 
which were connected to binding posts or studs.  This is the receiving 
apparatus which I have described in my answer to question 23." [NTGW, Leland 
I. Anderson, Twenty First Century Books, 1998, pp. 41-42.]

The "picture" is posted at 
http://www.teslascience.org/archive/descriptions/picture07.htm .  A diagram 
of the primary circuit is posted at 
http://www.teslaradio.com/images/14-035.gif .

Gary