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Re: Efficiency of various coil form designs (fwd)



---------- Forwarded message ----------
Date: Wed, 20 Jun 2007 00:31:06 +0000
From: Sparktron01@xxxxxxxxxxx
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Efficiency of various coil form designs (fwd)

Jeff (and Bill)

Thanks for the great historical and scientific background
on the topic of secondary geometry / construction techniques/
TC operation versus application.

 Jeff, excellent website and on-line virtual museum.

Best Regards

Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA


 -------------- Original message ----------------------
From: "Tesla list" <tesla@xxxxxxxxxx>
> 
> ---------- 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-Co
> il_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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