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Any Tesla Coil fans out there?

Discussion in 'General Electronics Chat' started by DerStrom8, Feb 16, 2011.

  1. BrownOut

    BrownOut Banned

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    The thing about the polypropylene caps is they are rather new on the scene, so you'll need to talk to someone who is currently building TC's or has built them recently. Good luck.
     
  2. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    Looking back, and I have a hell of a lot of back to look at I have had my share of bites from just about every coil imaginable to man. Among the first was a REO Lawnmower engine when I grabbed the spark plug. That was only preceded on a low voltage scale by shoving a butter knife in the toaster. :)

    However, as to all this on capacitors. I actually remember when high voltage doorknob caps were common place. The high voltage sections of TVs used a 1B3 high voltage rectifier tube and plenty of HV caps. Easily harvested for your building pleasure. Today the damn things trade like gold on a commodities market. Go figure?

    I also submerged my share of home brew caps in mineral oil as well as other HV projects.

    I built my first Tesla Coil back in 1964 as I mentioned in an earlier post based on a Popular Electronics article. Every month I looked forward to PE and QST magazines. Those were the only Tesla Coils I ever built so I am far from a guru on the subject. If anyone thinks tossing quarter million volt arcs is cool now, it was really cool then (or hot if you look at the spark).

    Anyway, solid state neon sign transformers weren't invented so that left the more practical transformers of the day to work with. The popular choice was a 15 KV 30 mA transformer running on 60 Hz unless you were elsewhere running 50 Hz mains power.

    Now I don't remember everything but even then screwing with capacitors and arc gaps was a *****. That discounting winding the coils. Wind and dope with corona dope. Over and over again. Then pray there was no breakdown. :)

    Possibly fortunately in 1964 there was no Internet. This left the home HV enthusiast with a library (I think they still exist) and thinking to do as well as magazine pictures in black and white.

    Now I figure it this way and forgive me if I am off base. Back then we made caps with sheets of glass and copper or aluminum foil. A few sheets of each and a simple wooden frame gets things going. I mentioned that many post ago. Granted tweaking and peaking can be a ***** but it should beat the hell out of trying to order **** from all over hells half acre from wherever on the internet. Aluminum foil and glass are still cheap and the visual aurora are priceless if the damn thing works.

    Just My Take
    Ron
     
  3. BrownOut

    BrownOut Banned

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    If these new caps work reliably, I'd say the price is a bargin! Personally, I'd just gamble the 20 bucks or so just to find out, but I don't have a NST. If someone has a working one for cheap, I'd buy it.
     
  4. dave

    Dave New Member

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  5. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    I have had my share of jolts, as well. I was about 6 years old when I got my first shock that wasn't static electricity. I was trying to recharge a 9 volt battery that wasn't supposed to be recharged :eek: I reached to unplug it from the wall and got a bit of a zap. It didn't hurt--much. It just scared the heck out of me! I was about ten when I tried to unplug something from an outlet and I managed to come in contact with the prongs of the plug. That time I hardly felt it--something just felt weird. Then, about a year later, I was playing around with a light desk that my dad made (stupidly, out of metal and without insulation on the switch contacts) and I accidentally touched something that was charged. I just felt the current pulsing through my finger, which again, didn't hurt, but it sure startled me! Then there were dozens of shocks from capacitors, ignition coils, flyback coils, neon sign transformers, etc.

    I have a bunch of plates of 1/4 inch glass, which I have considered using. I would need some aluminum foil (I've pretty much used it up on other capacitor attempts) for the plates, and I think I found out I would need 10-15 of these in parallel. If my bottle capacitors don't work, I might try this, too.
     
  6. EN0

    EN0 Member

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  7. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Hahaha! That is ridiculously hilarious! Who would decide to do that kind of study??? :D
     
  8. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    1/4 inch is pretty thick glass. Thickness of 1/8 th or 1/16 th would be better. Don't forget plexiglass either as an insulator between plates. The Dielectric can be pretty cheap and available. Before all the new stuff early caps were aluminum foil and wax paper.

    As I mentioned I am not a guru on Tesla coil caps but the cost of building and experimenting with simple caps is cheap.

    Ron
     
  9. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    I have 3 NSTs-- the 9/60 that I've been talking about, a 15/30 that I would like to hold on to for now, but I also have a 7.5KV, 30mA one that I suppose I could part with, if you're interested. It's the older style with a pull-string switch, and the output leads are rather short and the insulation is going, but If you don't mind this, make an offer. :) I'll see if I can post a couple of pictures for you.

    I wondered about that. I made a single capacitor with just one of those pieces of glass and aluminum foil, and it ended up having a capacitance of only about 500pF, which is why I decided I would need so many of them. I may be able to get my hands on plexiglass--I'll have to talk to some people. Thanks for the suggestions!
     
    Last edited: Feb 20, 2011
  10. killivolt

    killivolt Well-Known Member

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    Last edited: Feb 20, 2011
  11. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    • Like Like x 1
  12. killivolt

    killivolt Well-Known Member

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    I liked the use of the Microwave oven Transformers nice touch. The attachment isn't working though. Attachment 51438 When click it say's vBulletin Message
    Invalid Attachment specified. If you followed a valid link, please notify the administrator

    kv
     
  13. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Thanks, KV. If you're talking about the attachment in the chokes blog, I have seen it already. I'm not sure if you're able to edit blogs after you post them, though. If it can be done, please let me know! :)
     
    Last edited: Mar 4, 2011
  14. BrownOut

    BrownOut Banned

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    Roll your mouse over the blog title, and a pencil will appear. Use that to start the editor. Thanks to Ericgibbs for schooling me on the procedure.
     
    Last edited: Mar 4, 2011
  15. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Ah, many thanks! The problem is fixed, now :)
     
  16. BrownOut

    BrownOut Banned

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    I don't know about the idea of using a MOT. The inductance is high at line frequencies, and probably just too much to work in your setup. I'd think about using real RF chokes instead. You can buy surplus torroids and wind your own to save money.
     
  17. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    You think so? The reason I'm trying to use MOTs is that I am trying to build this Tesla coil out of parts that I have lying around already. I have a bunch of MOTs just sitting in my workshop and I'm trying to find a use for them. ;)
    Do you think it would work better to use the primaries of the MOTs (would it decrease the inductance enough to allow it to work)? Or would different transformers work? (In case you can't tell, I'm kind of stuck on using transformers for inductors right now :) ).
    Thanks for the help!
     
    Last edited: Mar 4, 2011
  18. BrownOut

    BrownOut Banned

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    I just think the inductance is too high. Think about it, when you plug a transformer in your wall socket, and have no load connected, the current through the primary is very low. That's about how much current you'll get in your primary of your TC. I might be wrong or I might be right, but I think you're gonna need another solution.
     
  19. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    I see what you mean. I guess I'll keep my eyes out for a better inductor, but I'll hold onto the transformers to see what they do.
    I once read about a guy who just used coils of wire for his inductors without a core, but his Tesla coil was just a small one. Is there any way I could do this with mine? I'm just thinking that it would save me some money if I could leave out the core.
     
  20. BrownOut

    BrownOut Banned

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    Do you own a sazall? You might saw apart those MOT's and remove some coils to make a lower inductance choke. Just use the center portion of the core and wrap enough turns to get the inductance you need. A good bi-metal blade and lots of lubracating oil should do the trick. Otherwise, spend a couple bucks on a good ferrite core. Whatever you use, just make sure it's substantial enough to never go into saturation.
     
    Last edited: Mar 4, 2011
  21. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    I'm sure I could get my hands on one ;) :D
    I might just give that a try! Thanks!
     

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