Posted: Thu Feb 28, 2008 5:18 am Post subject: Reply with quote
Practical Magnifier Construction Principles Making it work
From the pages of Exotic Research Report magazine, January-March 1999 issue.
This was actually a pretty good article from Richard Hull in Virginia. It talks about the magnifying "extra coil" setup Tesla developed in Coloroado Springs in 1899. Seems these folks reproduced the configuration there and found out a lot of things about how the system works-kind of a balancing act, as it were, something I've always felt when doing this work. It's as much a matter of "feel" as anything.
"One watt-second of power is not much. As normally thought of, it is just one watt delivered over a period of one second. Oh what a vast difference however, can be the manifestation of one billion watts delivered for one billionth of a second."
There is a great gulf between the germ of an idea and its physical embodiment. Often the originator of an idea carries his concept no farther than the philosophical stage where musings and ruminations about possibilities are considered. Many times the idea is carried through to the theory stage, often containing many mathematical entanglements. This delights the acememic community, in their quest to give the idea a sound theoretical footing.
In our modern age it is sad to say that in many instances mathematics is often the language of all ideas and many academicians are quite happy to fold their hands at this point and consider the matter closed or at least leave the "hands on" stuff to the engineers, technicians and manufacturers. The true experimentalist takes and idea through an experimental phase and finally to a working model. Much of research today revolves around "big science", with multi-mllion dollar instrumentation and multi-million dollar installations. How can a lone wolf inventor play the game?
Nikola Tesla was one of those people that come along rarely in science whose ideas always came along faster than they could be developed. His funding was limited and his ties to established institutions and industry were virtually nonexistent. His inventions of alternating current electrical motors and distributiuon of polyphase currents secured for him a reputation of the greatest living electrician by the mid 1890's. In his own time, people knew that Tesla was a brilliant experimentalist and discoverer. His interests turned to high frequency oscillations and he invented a resonance based transformer system which is known as the Tesla coil.
It is not the purpose of this paper to give the detailed whys and wherefores of Tesla coil theory. The Corums have covered this in some detail at previous symposia and in a number of articles. The reader is referred to their work for fine details. I will however give a broad and rapid overview of the basics of the Tesla coil and ultimately the magnifier.
The classic two coil Tesla oscillator consists of a primary tuned circuit and a loosely magneticly coupled resonator, (usually 1/4 wave resonant) which uses internal resonance within the resonator to create huge output voltages. These voltages are, in general, limited by the inductance ratios of the two coils and their internal losses. Telsa realized quickly that the power capabilities of this seminal device were limited by the required loose coupling of the resonator.
If the coupling of the standard two coil Tesla oscillator is increased to yield more efficient power conversion, then the resonator and the primary will interact in a manner that causes frequency splitting and the energy is now spread over a broader range of frequencies. This is definitely not desirable in tuned circuits! Tesla ultimately realized that if he could use a two coil oscillating system which was very tightly coupled and specially constructed to provide an extremely low impedence output, then he could simply inject this large quantity of of oscillatory energy directly into the base of a third coil. This coil would be an ultr-efficient, low loss quarter wave resonator.
Notice I said, "he ultimately realized". As with many ideas, there is a long road between the germ and a working model. Tesla would make plenty of mistakes and waffle back and forth over how the system ultimately worked. Tesla would go on to construct his ultimate working model in Colorado Springs during 1899.
It is a little known fact that Tesla would ultimately see the value of huge electrostatic capacities loading the output resonator. This could be seen in the untested Wardenclyffe tower later assembled on Long Island in New York.
The Tesla Coil Building Community
The Tesla coil builder is a creature of habit. The same Tesla coils that our grandfathers made are still being made today. Most of the builders are just tyros and looking for sparks and this is fine, but the monkey-see-monkey-do mentality took a mild turn for the better when, sometime during the 70's, the toroidal capacitance replaced the drawer pull or door knob of grandpa's coil. Much of the early model changing seems to have been accomplished by Bill Wysock who set a standard fore the finally evolving Tesla coil building community. At least we're on the move!
The output spark and appearence of many coils improved but there was still the log jam of similar looking and acting systems being mindlessly replicated. Our group was formed in 1988 and set as a goal: The modernization and improvement of the Tesla coil through experiment only, and not through blindly following theory. We literally set out to not follow in the footsteps of anyone! This is empiricism at its extreme! We knew we would be reinventing a lot of wheels, but hopefully we would see a lot of ground that had not been covered by the Tesla coil building community. Remember, output spark and energy efficieny were our goals, not the wireless transmission of power, not the vindication of Nikola Tesla, nor the nebulous cohering of zero point energy. In short, our goals seemed realizable.
We read assiduously all of Teslas works that had been published, which were two in number. The early 1984 compilation by T.C. Martin was interesting, but shed little light on magnifier basics. The Colorado Springs Notes, taken by Tesla during his brilliant stay in that city, represents the bulk of the knowledge on magnifier systems prior to the 1980's. In addition, we read a number of "modern" Tesla coil theory books available prior to 1990. We quickly realized that much of what Tesla had to say diverged from the modern texts. We wondered why this was so, but continued on with our experiments.
In 1992, Leland Anderson gave us another valuable reference with the direct, informal interviews of Tesla by his attorney some ten years after the closing of the Wardenclyffe project. This work, Nikola Tesla On His Work With Alternating Currents, answered a number of questions which remained after our initial magnifier successes.
This absolute disregard for convention through empiricism, which was yielding incredible results, was a thrilling period for us. We had helped break a mold and, through distribution of our video tapes, we had assisted other builders in understanding experiment must never end. We were also pleased to find that Tesla had often, in a convoluted manner, stated much of what we had learned. Unfortunately many of our "great discoveries" turned out to be lost Teslarian genius. Tesla never published much and he was often convoluted and perhaps even devious in some instances. His Colorado Springs Notes are something that we studied constantly for over four years. There is much in his notes that becomes manifest only upon experimentation.
In an effort to simplify the Colorado Springs Notes of Nikola Tesla for the coil building community, I have just recently produced a book. This book anotates the daily notes of Tesla from a "plain speak" point of view from the builder. The germ of Tesla's notes is reduced to a more palatable form for the modern technician/builder. I also link Tesla's work of the day to our own experiences paralleling his activities and offer more modern solutions. This book includes more detailed information on magnifier construction along with numerous full page pictures of our work in an appendix. It is entitled, The Tesla Coil Builder's Guide to the Colorado Springs Notes of Nikola Tesla.
Turning to the Magnifier
We felt that we had mastered the classic two coil system with "Nemesis" and in 1991 planned a slow but methodical investigation of the three coil system which Tesla had labeled his "Magnifying Transmitter". Again, determined to succeed regardless, as we started by researching how others built the system. There appeared to be no others than Tesla!!! His notes were involved and often fragmentary. So much of the hearsay and coil builder "noise" about magnifiers turned out to be pure bluster.
No one that we knew had ever attempted one and the majority of those who claimed knowledge said that the system couldn't be made in a smaller model. Robert Golka had attempted to replicate the original Colorado Springs machine of Tesla, but never published detailed data on his work. Toby Grotz did publish an overview of Golka's last system set up in 1989 for the International Tesla Society, but again, no new insights were given. It appears the Golka machine was constructed not so much to experiment with magnifiers, but to investigate the deeper issue of wireless transmission of energy.
It was beginning to sound as if only Tesla held sway over his ultimate machine. We suspected that the same neglect of experiment on behalf of the building community was at fault, as we had discovered with our two coil investigations. We soon found that the Corums were speaking about an interesting idea regarding the magnifier as a driver/resonator type of system, all understandable within transmission line theory. We were intrigued and immediately found a good base for understanding the system. Tesla himself, waffles on the critical idea of the use of the secondary within the driver of the magnifier several times in the Colorado Springs Notes. This seems to be the area where the amateur community also falters.
By 1990 we had heard the following generalizations:
The primary should be 3 to 5 turns and of relatively low inductance.
The capacitor in the primary circuit should be relatively large.
Small coils used a good single gap and over a kilowatt, a rotary gap was a must.
A moderate terminal capacitance was needed to shield the top turn from corona leakage.
Use heavy wire in the secondary and try to keep the turns count down and the inductance moderate.
Use short, fat connectors throughout the primary circuit.
This was the prevailing school of thought.
By 1991 we had discovered that there are many easier and simpler ways to achieve incredible results from a two coil system. Many of these techniques flew in the face of the above conventions, but still obeyed scientific laws. The ultimate embobiment of our two coil system was the "Nemesis" system operated from 1991-1993.
One of our first observations was that large 12 turn primary inductances of many microhenries worked just great and allowed the use of much smaller capacitances. The primary heated a lot less (reduced eddy current losses). This gave a reduced di/dt which was a sacred cow to the radio theorist. With this, the primary connections could be quite sloppy. This does not imply that they should be!
We found that to counterbalance the increased primary inductance, massive secondary inductances could be brought into play. We further found that the moderate sized toroids then used could be increased by one full order of magnitude and the result would be a fantastic increase in the amount of energy handling capacity of a relatively small system! We determined that for moderate to large systems, a 2.5:1 ratio was a good length to diameter ratio for the output resonator.
We achieved superb performance up to 3800 watts with simple static series gaps of special construction. A rotary wasn't used until we went over 5000 watts. Why were we getting results equal to or better than the standard while flying in the face of convention? We determined that convention wasn't wrong, only that there were several ways to make Tesla coils as long as a synergistic balance was maintained between the components.
We would later find that Tesla, in his own Colorado Springs notes, would recommend relatively large primary inductances as long as the interrupt rate of the primary circuit was a small fraction of the resonant frequency. Our superior performing systems utilized what seemed to be grossly oversized terminal loadings for the resonator dimensions. This too would find an analog in Tesla's Wardenclyffe tower. We found that the secret was to load the resonator to the maximum point it could withstand without breaking down. We rapidly achieved arc lengths of four times the resonator winding length.
There were many secrets to be learned in working this though. One was to never allow any wire to enter the resonator at the top or bottom under any circumstance! This is routinely done by the amateur community. We preferred the inverted cone archemedian spiral primary in a very shallow form. We provided an open, grounded guard ring around the outside primary turn in order to protect the primary circuit from the many impacts of arcs from the secondary. We developed special techniques of directing the output arcs without using the standard, energy wasting, "take off" rods. In short, we learned a lot about electrostatic field control.
The more we experimented and assembled systems, the more of the Corum's work we verified to our own satisfaction. The notes of Tesla also started to make more sense to us after many returns to them. It seemed that mathematics supplied only a basis to begin engineering efforts and would never be a rigid guidepost for the finished manufacture of systems. This we had also found to be the case withing the two coil system. It became quickly apparent that the spark gap and resonator terminal loading were more critical to the magnifier system than the standard classic coil! More creative juices flowed as we worked out geometries for the driver system which would allow the very tight coupling demanded. We developed new rapid quenching gap systems for the task at hand. A number of photographs have been included showing some of our magnifier systems.
Like Tesla, we made some false assumptions based on limited empirical data, but ultimately with numerous different magnifier systems behind us, we literally began to get a feel for the system construction. This has an analog among production engineers of industry who have so thouroughly worked with just one systemtype that they develop an intrinsic "feel" for what works. Many of these subtleties do not jibe with theoretical machinizations, or answer the call of rigid mathematical formulae. They are often called... "Fudge Factors", "Catch-22s", "Gotchas", etc, which often conspire to confound rigid engineering attempts.
I shall borrow from one of my fellow engineers in the group, Dave Sharpe, who so eligantly diagrammed the system conundrum of synergy balance, and supply a diagram here.
Imagine an ideal magnifier system as an inverted cone balanced on its apex with radial arms extending outward from its base which is now on top. On each of these arms is placed a sliding weight which represents vital system parameters such as spark gap dwell time and repetition rate, Primary inductance, primary capacitance, Secondary inductance, resonator inductance, resonator frequency, internal losses, applied voltage, top resonator terminal loading etc. As each parameter is adjusted, (ie. slides along its radial arm), the system is thrown out of balance and one, some, or all of the parameters are needed to be altered to bring the system back into harmonious balance. It is obvious that the system might be balanced in a thousand ways, but nonetheless, balance must be maintained. So there are many possible construction and operation avenues. The critical point that we learned in two coil construction was that the best system in the world can be operated in an improper manner. This is most often seen as improperly conditioned power from AC mains. Often the spark gap, which might be constructed perfectly, is not operated at its optimum point or lossy materials are used in coil forms or insulation.
http://www.stargazing.net/Astroman/Magnifier.html
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Man lives in the sunlit world of what he believes to be reality. But there is, unseen by most, an underworld, a place that is just as real, but not as brightly lit... a Darkside."
Last edited by junglelord on Thu Feb 28, 2008 3:11 pm; edited 11 times in total
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