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DRSSTC: Dual Resonant Solid State Tesla Coil

Discussion in 'General Electronics Discussion' started by kilovolt, May 4, 2015.

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  1. kilovolt

    kilovolt

    8
    6
    Jun 27, 2012
    I would like to share with you a small DRSSTC I built last year. Spark legnth is a bit more than 1 meter. The coil is not optimally tuned and I didn't take the time to build it entirely with case and so on, because I'm in the building process of a small QCW DRSSTC at the moment, which will be more fun I think.

    [​IMG]

    The driver:
    [​IMG]

    The interrupter:
    [​IMG]

    [​IMG]

    Power section: Fullbridge with FF400R12KT3 Bricks:

    [​IMG]

    The used Infineon IGBT-Bricks:

    [​IMG]

    Some pics of the resonator:

    [​IMG]

    [​IMG]

    [​IMG]

    ... and the primary cap:
    [​IMG]

    Thanks for your interest :)
    kilovolt
     
  2. hevans1944

    hevans1944 Hop - AC8NS

    4,647
    2,169
    Jun 21, 2012
    Nice to see photos from someone who really knows how to build Tesla Coils!
    Is the top-loading toroid capacitance "hat" constructed from flexible aluminum duct tubing? How is this supported in its interior? Wood? Plastic?
     
  3. kilovolt

    kilovolt

    8
    6
    Jun 27, 2012
    Thank you very much for your kind comment, hevans1944. You're right, the topload consists of an aluminium duct tubing.. In the center it is hold by a round acrylic glass plate (plexi) and some hot glue :oops:. It is not a very good solution, but actually the whole setup is a bit improvised in several ways. For example during longer runs the nails of the white primary-coppertube supports are getting hot due to the eddy currents from the magnetic field of the primary coil and they are melting the plastics holding the copper on the base, so I have to find another way to mount the primary coil.

    At the moment I'm building another DRSSTC coil type, so the improvements for this project have to wait until the other one is finished.

    A video of the operation:


    Have a nice day.
    kilovolt
     
    Last edited: May 5, 2015
    hevans1944 and Supercap2F like this.
  4. hevans1944

    hevans1944 Hop - AC8NS

    4,647
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    Jun 21, 2012
    You could probably (with a lot of effort!) remove the nails one-by-one and replace them with nylon screws.

    Are you member of any of the Tesla Coil Web Rings? It is always a pleasure to see what creative folks can accomplish with modern technology applied to 19th Century resonant transformers. I happen to be a big fan of Nikola Tesla and would someday like to attend one of the "concerts" where REALLY BIG Tesla Coils are a featured part of the show, complete with actors in chain-mail suits and Faraday cages and music modulating the Tesla Coils. Alas, for now I have to be satisfied watching videos.

    After watching your video post there was another YouTube video of a fellow working on his Master's Thesis who demonstrated a moderate sized coil that could be switched between rotary spark-gap excitation and DTSSTC operation. Solid state seems to be the way to go if you want to scale up in size. His primary col was conical, narrower at the base opening up to the top. He had a grounded protective "arc ring" spaced above it (with the requisite small gap to keep the ring from acting like a shorted turn) to protect the electronics, but in the demo video all the arcs were straight up toward the ceiling, emanating from the raised right arm of a Nikola Tesla "action figure" doll he had modified by inserting a copper wire tipped with a steel needle into the arm. Fun stuff!

    Please feel free to post more pictures of your current work. Many of us here really enjoy arcs and sparks, responsibly handled.
     
  5. kilovolt

    kilovolt

    8
    6
    Jun 27, 2012
    Let me thank you once again for your friendly answer, hevans1944.

    I don't know where to get thin nylon screws or fiber glass nails, but you're right, this would solve the problem for sure. Maybe I'll try a solution with cable ties, but that doesn't look very nice.

    In the past I was a member of a high voltage ring and a tesla coil webring indeed, but after some time I found, that most of the visitors of my webpage were directed straight to the webring when they called my page. That was the reason I cancelled the membership. Maybe I should give it a try once again.

    Hevans1944, do you build tesla coils as well? In your profile I saw you are/ were Particle Accelerator Engineer! So you really must be an expert in physics and therefore regarding high voltage as well.

    Yes, indeed. Solid state is coming up more and more. Power-MOSFETs and IGBT-Bricks are being cheaper, faster and easier to drive than some years ago. This year I bought a bunch of IGBT power bricks for very little money from a company, which was producing solar power systems. They had to declare bankruptcy but there was still a big stock of power electronics lying around. They selled it all for peanuts.

    High voltage is my favourite hobby since more than 20 years now. Coiling is nice, but there are other interesting high voltage and high frequency experiments as well. For example I'm also interested in wimshurst machines, cockroft walton multipliers and similar devices. If there is an interest in this forum, I could of course show some other projects too from the past. My current project, a QCW-DRSSTC, is not yet finished and doesn't work properly at the moment, therefore it will not be very interesting to share at the moment, I think. Unfortunately I've not much time anymore to work with these things.

    If high voltage and vacuum experiments in general are not against the rules in this forum, it would be a pleasure for me to show some of the stuff :)

    Best regards
    kilovolt
     
    Last edited: May 6, 2015
  6. hevans1944

    hevans1944 Hop - AC8NS

    4,647
    2,169
    Jun 21, 2012
    Here is a link to the forum Terms and Rules, which can also be found at the bottom of each page. I don't think anything is forbidden when discussing high voltage and vacuum experiments as long as all parties to the discussion are knowledgeable and competent in those areas, as obviously you are and I believe I am. We do try to discourage the incompetent from messing with stuff that can harm them or others.

    I am no "expert" in anything. I have worked in electronics since the 1950s, first as a newbie experimenter, later as a trained technician, and still later as an electrical engineer. Most of my work has been interdisciplinary in nature, and all of it has been with national defense contractors. My electrical engineering degree is a Bachelor of Electrical Engineering, awarded by the University of Dayton School of Engineering in 1978. So it has been awhile since I worked in the halls of academia. My career as a particle accelerator engineer began in 1996 when I replaced a real physicist who wanted to work for Argonne National Laboratories, where they have some really BIG accelerators. All I knew when I applied for the job was what I had learned from reading text books. I had no hands-on experience with any accelerators whatsoever. Fortunately, I am fairly intelligent and a quick learner. It was a real "character building experience" learning how to keep the beast operational. But it was also a lot of fun and I learned a lot about accelerators.

    I have never attempted to build a Tesla Coil, and haven't visited any of their web rings for quite some time. As a kid, I played around with a genuine Ford ignition coil packaged in a wooden box with adjustable interrupter contacts. And I toyed with the idea of building one using plans in Alfred P. Morgan's seminal text for young boys, "The Boy Electrician". But vacuum tubes and electronics came along and distracted me for the next sixty-something years. But I never lost my passion for things high voltage. I "borrowed" an electrostaic generator from the electrical engineering lab while I was an undergraduate student, intending to restore it to operation. My professors wondered why I was "wasting my time" since there was no practical use for such a device, but I was allowed to take it home. This was a Voss machine, not a dual counter-rotating disk Wimshurst machine. I wanted to replace the brush electrodes with an ion source salvaged from home smoke detectors, thus eliminating a source of friction.

    Cockroft-Walton multipliers are another thing I like to "play" with. The particle accelerator I maintained used one to create 1.7 MV terminal potential. Most laboratory high voltage power supplies also use this circuit for voltages up to 100 kV or so, limited mostly by breakdown in air. For really high voltages, a form of Van de Graaff generator using a chain of insulated metal pellets is used. This accelerator is called a pelletron and is custom-made by National Electrostatic Corporation for customers all over the world. I got to see (and walk inside of, after they pumped out the sulfur hexafluoride insulating gas) one at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. This was a tandem machine (negative ions in, positive ions out) capable of 25 MV terminal potential. At that level of acceleration, virtually all the electrons of the accelerated negative ions are subsequently "stripped" off before passing through (and accelerated again by) the high-energy column. These positive ions gain additional energy proportional to their positive charge, so (for example) a 25 MeV ion with a +10 charge gains an additional 250 MeV energy, leaving the accelerator with 275 MeV energy. Compare this with my "toy" accelerator that on a very good day can produce ions with only a +4 charge. Some users of the Tandetron accelerator (the model I used) retrofitted their machines with pelletron chains, and some replaced the Cockroft-Walton vacuum tube oscillator exciter with a solid-state oscillator, as was done at the Michigan Ion Beam Laboratory in Ann Arbor. They also equipped their machine with a TORVIS negative hydrogen ion source (designed and built by NEC) to perform simulated solar wind experiments on hardened electronics used in outer space.

    So, my professors in the 1960s and 1970s were wrong. There are many practical applications for electrostatic generators, they just didn't know about them yet.
     
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