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Re: Efficiency of various coil form designs (fwd)
---------- Forwarded message ----------
Date: Mon, 18 Jun 2007 08:02:23 +0100
From: James Howells <james@xxxxxxxxxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: *** SPAM *** Efficiency of various coil form designs (fwd)
Thanks to Jeff Behary for his post.
The History and Electrotherapy Museum site is fascinating
With out this posting I would never have known about this important
historical collection and well researched records
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----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, June 18, 2007 1:48 AM
Subject: *** SPAM *** Efficiency of various coil form designs (fwd)
>
> ---------- Forwarded message ----------
> Date: Mon, 18 Jun 2007 00:58:00 +0000
> From: Jeff Behary <jeff_behary@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Efficiency of various coil form designs
>
> Hello all,
>
> This is "round two" of my ramblings :) ...
>
> I agree with Bill Wysock 110% on the various forms of coil forms and their
> attributes. I'd like to add a few comments on that subject.
>
> The efficiency of any form of Tesla Coil depends on the application and
> use
> of the coil also, and this hasn't been mentioned. Of course, maximum
> spark
> length would imply resonance, and for most modern coilers that is a good
> indication of performance. But for specific applications using Tesla
> Coils,
> the "qualities" of the discharge is sometimes more important.
>
> Starting in the teens companies such as H. G. Fischer, Campbell Electric,
> Frank S. Betz, Remco, Sterling Laboratories, McIntosh Electric Corp.,
> Master
> Electric, Haliwell-Shelton, Shelton Laboratories, Rogers Laboratories,
> Bleadon Dun, Chicago Scientific, Energex Co, Challanger, Violet Ray
> Corporation, Browne Electrical Laboratories, LE Knott Apparatus Company,
> Cenco, Renulife, Eastern Laboratories, Master Appliance, Gibbs Brothers,
> Sheidel-Western, Amos Cato, Contra-Pole, Wappler, Waite & Bartlett,
> Machlett, Elco-Lindstrom, Fitzgerald, Parco, Re'juvin Laboratories,
> Tuckers
> Mfg. Co., Viracorp, A. S. Aloe, Ajax, Electro-Technic Products, Fromm
> Industries, and many other smaller companies in the US made small Pancake
> Coils for therapeutic use known as "Violet Rays". These machines were
> made
> to produce a spark about 1" long consuming from 15 - 30 watts of power.
> A requisite of the spark was to create local heat through special geissler
> tube that conducted the current to the skin.
>
> The measure of the efficiency of these machines was not spark length but
> rather the nature of the spark. It must have been able to "fulgerate" (a
> form of spark cautery) the skin at short spark lengths (1/8- 1/4"), heat
> below the skin to a noticeable degree when in direct contact with the
> body,
> and dehydrate the skin when sparking 1/2" or more from the surface. A
> further embodiment of some of these machines was the ability to power a
> small X-Ray tube for treating skin disorders. (Dangerous I know, but its
> history).
>
> At first sight these machines may seem like old rubbish, but I would pose
> a
> challange for someone to try and make a helix coil that still fulfills
> these
> needs and can be made 1" diameter and 3" tall (Primary and secondary coils
> included). It isn't impossible - a very fine wire secondary of small
> diameter can be made to create a 1" spark, but often the output is too
> feeble to be used in the above manners. Of the hundred or so machines of
> this variety that I have owned, all of them used
> Pancake Coils. They were all sightly different in design from model to
> model.
>
> Second, as far as "visible" efficiency goes, these same small coils can
> produce sparks 2 - 4" long when the input power increased to 75 - 100W.
> (For those familiar with the circuits, adding an extra magnet coil or two
> in
> parallel will do this) The small Pancake coil must be thrown in oil to
> avoid
> spark-overs, but this is also pretty good for a 1" x 3" coil, P & S
> included.
>
> Sorry in advance for the crude setup, but I have some photos of that:
> http://www.electrotherapymuseum.com/2006/VROil/index.htm
>
> Next application is Tesla X-Ray Coils. This is an application that is
> 100%
> possible to use today for portable X-Ray machines, even with the modern
> Coolide tubes. My Kilowatt twin Pancake Unit
> can demonstrate some fierce RF flames 7-8" long that could be enclosed in
> the normal housing with oil and an X-Ray tube (lead lined of course).
> http://www.electrotherapymuseum.com/2007/HighResCoils/KilowattKinraideFlames.htm
>
> [An interesting note as to how to control the filament voltage - another
> Tesla concept 100% - impedance - a loose coupled coil wound on the outside
> of the primary can be used to power the
> filament of the tube by impedance - controlled by a rheostat in the same
> way
> as a filament transformer.
> http://www.electrotherapymuseum.com/2006/Figure1/images/Fig1-04.jpg ]
>
> This is an application where cylindrical Tesla Coils have almost always
> failed, with exception of two oil-filled versions made by LE Knott
> Apparatus
> Co. and Elihu Thompson:
> http://www.electrotherapymuseum.com/Library/LEKnottApparatus/index.htm
> http://www.electrotherapymuseum.com/2007/ElihuThomson1/pages/ff0596.htm
>
> In these two coils the Primaries extended the whole lengths of the
> secondaries to allow very close coupling such as the coil in this article:
> http://www.electrotherapymuseum.com/TeslaArchive/ATeslaCoil/index.htm
>
> Even some Pancake Coils for this purpose failed. While nearly all Tesla
> Coils can produce X-Rays with a proper tube, the qualities of the
> discharges
> greatly effect the ability of the X-Rays to make proper radiographs. Its
> the qualities of the discharge and style of X-Ray tube that determines
> whether your X-Ray plate will show a pretty picture of bones or a blurry
> mess.
>
> The same style coil when powered by a tank circuit to produce long sparks
> may produce discharges 12 - 16" in length or more. Despite the increase
> in
> spark length, the discharges are still hot in nature. The heat can be
> felt
> several feet away, and if the spark touches your skin you are in for a
> painful surprise (bad RF burn):
> http://www.electrotherapymuseum.com/Forgotten_Tesla_Technologies/Early_Prague-Coil_Testing/index.htm
>
> One of the few areas of the past where helix coils were preferred was for
> surgical Tesla Coils. A thick wire secondary (18 AWG) on a small coil
> form
> (2" diameter x 4" long) with a 1/4 or 1/2 KW power can produce up to a hot
> 1" spark all day long for cooking and cutting tissues. It sounds horrid,
> but many lives were saved this way. In the case of malignant tissues, the
> cooked tissues/cysts/etc. could be safely removed without reinfecting
> other
> parts of the body with infected blood. There was little bleeding
> involved,
> and recovery time was much sooner and with a greater success rate than the
> scalpel.
>
>
> Aside from medical apparatus, early Tesla coils were used commercially in
> wireless telegraphy devices as well, but I don't have much experience in
> that arena to comment on the nature of the sparks produced for this. I
> have
> attempted though to make some color renderings of the coils Tesla
> created for this purpose. Most had mercury interrupters.
> http://www.electrotherapymuseum.com/TeslaArchive/Construction.htm
>
> Jeff Behary, c/o
> The Turn Of The Century Electrotherapy Museum
> http://www.electrotherapymuseum.com
>
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