Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx> Hi Chris,Good questions. Yes, all "can" work as you descibed. A primary is there to couple the initial discharge energy from the oscillation and primary energy to the secondary. How the primary is configured certainly affects the magnetic field and energy transfer over energy transfer time. But, the proximity of coil A to coil B can be manipulated to compensate and find a happy medium. You can insert a primary internally as a helical, flat, cone, inverse cone or whatever. You can insert the primary helical below the secondary or right on top of the secondary. But, in all these diverse configurations, there are some electrical rules you are forced into. One is primary to secondary arc over. If one is too close to the other, the primary can arc directly to the secondary. So, physical space is needed to prevent the arc over. Also, the coupling is very important. Too much, and the energy transfer is too quick (coils are too close to one another). To far apart, and the coupling is very low resulting in a very slow energy transfer. What has always been considered ideal, is to transfer energy as fast as possible (resulting in lower losses) without troublesome arc overs, racing sparks, quenching losses, etc. If you can achieve those optimums, that is all that is necessary. But, it may be helpful to know that everything you have stated as a possible configuration has already been done, a long time ago.
When it comes to coupling and energy transfer, you "really helps" to know the coupling expected before you build, otherwise your simply a monkey with a stick poking at a termite hill. Programs today can get the coupling exact and better than you can measure. It's weird, coupling for the longest time was one of those "must measure to be even ballparked", but today, the programs are "actually" better than the measurement (seriously). That statement is due to the tolerances of equipment. When it comes to coupling, programs like Javatc will hit the nail on the head every time. There were a lot of hours and many people here (and no longer here) that made that possible. Those that missed those days truly missed out on a really new phenomenon with coiling physics (meaning simply there was an organization with a leader who was ideal for detailing each step needed to go to to the next level = TSSP = Paul Nicholson).
Certainly you can do all the configs you mentioned, but do yourself a favor use a program that will output some data to help you decision.
Take care, Bart Tesla list wrote:
Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx> Hello,There's been some discussion about internal primaries lately, and I was wondering if there are any other primary designs which could possible be easier to build or more efficient than a classic flat spiral or helix. For example, could a primary wound externally on the same former as the secondary but several inches below where the secondary winding starts work? Or what about a primary actually wound on top of the lower part of the secondary windings, sufficiently insulated? What are the consequences of such schemes and would they work at all?Thanks, Chris -----Original Message----- From: Tesla list [mailto:tesla@xxxxxxxxxx] Sent: Thu 4/12/2007 4:34 PM To: tesla@xxxxxxxxxx Subject: Re: Tesla coil on Ebay; 80-300' lightning? Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx> Not very well. Larger secondary diameters are needed. Given turn requirements to meet inductance's needed, 8" is too small to be practical. You would end up trying to wind a 6.5" diameter coil and it would have to be helical adding to the difficulty with coupling, placement, and mechanical winding. Either external or internal is electrically/magnetically equivalent, but practicality is best external with that small of a coil. Take care, Bart Tesla list wrote: >Original poster: "david baehr" <dfb25@xxxxxxxxxxx> > > >Hmmm, would a internal pri work with a smaller coil , say 8" dia. ???? > > >From: "Tesla list" <tesla@xxxxxxxxxx> >To: tesla@xxxxxxxxxx >Subject: RE: Tesla coil on Ebay; 80-300' lightning? >Date: Tue, 10 Apr 2007 19:33:17 -0600 > >Original poster: "Hans Schattenmeister" <klugmann@xxxxxxxxxxx> > > > >. The coil was 5' in diameter, had an > >internal primary and stood about 25' tall. > > > > > > > > > > > > > > > >---------- ><http://g.msn.com/8HMBENUS/2734??PS=47575>MSN is giving away a trip >to Vegas to see Elton John. Enter to win today. > >