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My Ignition coil powered Tesla coil
Posted by Rockinriley14 on 2/28/2004, 8:15 pm Is there any way to improve spark length, i think maybe my secondary is too skinny maybe. I havent seen any under 2in diameter. I have another auto coil now too, any advice on dual coil system? when i hooked 'em both up it hardly worked at all. I tried series, paralell, no good. I also have a BIG OL microwave transformer, but it sucks (2-3cm sparks at best when hooked up to the TC. It was pulled from an old radarange (60's model, i believe.) It draws about 2400 watts, dims my lights and all. Any advice would be greatly appreciated! Thanks! =Rockinriley14=
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Re: My Ignition coil powered Tesla coil
Posted by Bert Hickman on 2/28/2004, 11:52 pm, in reply to "My Ignition coil powered Tesla coil" Hi, There are a number of potential problems, all which are combining to reduce your coil's performance. The secondary diameter should be at least 2", and you should wind it with some new 26 - 28 AWG magnet wire. Make the secondary winding at least 12" long. If your 2 liter pop bottle is made from plastic it will be very lossy - it should be made from a number of glass bottles (beer bottles work well) instead. You also may want to make a small toroid out of some small aluminum dryer duct once you've gone to a larger secondary. You may be able to connect the two ignition coils in parallel to get more current, but you may need to reverse the connections to the primary of one of them so that they don't "fight" each other. Eventually, a Neon Sign Transformer will provide you with much better performance. Do not use the microwave oven transformer - it's overkill for a small coil. You also may want to check out some of the sources listed on my site for more information, especially the Pupman or Tesla-2 mailing lists: Good luck and play safely! -- Bert --
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Re: My Ignition coil powered Tesla coil
Posted by Rockinriley14 on 2/29/2004, 1:57 pm, in reply to "Re: My Ignition coil powered Tesla coil" --Previous Message-- Thanks for the advice! I have spent lots of time on both the pupman list and the tesla-2 list researching and planning. I am planning on winding a new secondary for my coil. I have an acrylic tube about 15in long and 3in diameter, would this be a good form, or should I use PVC? I have read that PVC is not a good form but I dont know why. If I use #26 wire (which I can buy from McMAster-Carr cheap) how many turns should be on the secondary? I will probably use a flat spiral primary. Oh yeah, my lamp dimmer died Where can I easily get another transistor-powered lamp dimmer-like circuit, or build one? I have some power transistors I believe somewhere... I want it to be powered by AC as i dont have a good DC source, but i could build one i believe fairly easily. Also, the beer bottle cap- should the bottles be in salt water, or just wrapped in foil? Putting them in salt water would increase their capatince per bottle, right? Thanks for your help! =Rockinriley14=
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Re: My Ignition coil powered Tesla coil
Posted by Bert Hickman on 2/29/2004, 5:11 pm, in reply to "Re: My Ignition coil powered Tesla coil" Acrylic or PVC are both excellent coil form materials, and while a 3" x 15" secondary would be great for an NST powered coil, you may be underpowered if you try driving it from an ignition coil. I'd suggest a 13" long closewound winding of #28 AWG, leaving an inch free on each end of the form. This will give you about 900 turns. A flat spiral primary is also a good choice. Any good sized hardware store will carry incandescent lamp dimmers - these are generally no more than $4 - $7 apiece. However, the inductance of your ignition coil and the low resistance of your series heating element may be combining to overload common dimmers, so the new one may also fail. You probably should look for an inexpensive 7.5 - 12 kV NST instead, since it will be much easier to charge the beer bottle caps. You'll probably need at least a six-pack, or more, to bring your system into tune. And, if you can put the bottles in salt water you will increase the capacitance somewhat since you'll be eliminating the air space between the outer foil and glass. Sounds like you are off to a good start - keep us posted on your progress! Best regards, -- Bert --
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Re: My Ignition coil powered Tesla coil
Posted by Rockinriley14 on 2/29/2004, 8:58 pm, in reply to "Re: My Ignition coil powered Tesla coil" --Previous Message-- Well, I wanna NST and I am going to check around for one, unfortunately I live in the middle of nowhere, where old cars are much more plentiful than NSTs... where could I get an OBIT, are those easy to come by, and out of what? an old oil furnace, I suppose, but anywhere else? As for the wire, does #26 or #28 make a big difference? I just figured i'd be less likely to break #26, and it would allow for more power later on down the road >:} A beer bottle cap is sounding like my best bet. Would it be better to use several smaller bottles or a few big jars? I have several large pickle jars (a gallon or so apiece) sitting around. Is there a certain height-to-diameter ratio that works best for secondaries? =Rockinriley14=
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Re: My Ignition coil powered Tesla coil
Posted by Bert Hickman on 2/29/2004, 9:45 pm, in reply to "Re: My Ignition coil powered Tesla coil" You can often buy NST's on eBay for reasonable prices. Also OBIT's can often be had for free or little $ (just bring your tools!) from heating and ventillation places when they junk/replace oil furnaces. You can also buy them new from Grainger (look for "ignition transformer) or HVAC (that's Heating, Ventillation, and Air Conditioning) suppliers for $40-50. #28 AWG will give you more turns and higher inductance (desirable for technical reasons), and the smaller diameter is not a problem due to the relatively low current even at higher power levels. If you decide to significantly boost up the power later, you'll want to increase both the diameter and height of your secondary anyway. It really doesn't matter if you use smaller or larger bottles as long as the wall thickness is sufficient. Most beer bottles will work fine (small or large). I wouldn't recommend large pickle jars. Some folks have also made "bucket caps" using 5 gallon plastic (HDPE) buckets - check out bucket caps on the Tesla List archives. Secondary height vs diameter is not critical as long as the form is long enought to prevent flashover and the coil has reasonably high inductance (say 800-1500 turns). A minimum of 3:1 and a maximum of perhaps 10:1 for small diameter coils is in the ballpark - it's really not a critical parameter. Good luck and best regards, -- Bert--
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