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4 inch coil - - First light!!
Posted by Rockinriley14 on 7/17/2004, 11:19 pm my 4 inch is not up to par but is a BIG improvement from the ol' iggy coil 2 incher. However, I do have some questions about it. First, I have only a crude lashup of most components, and hardly any calculations & measurements. So, if i need a redesign of any component but the secondary it won't be a big deal. (I built EVERYTHING today but the secondary.) The secondary is 1500 turns of #28AWG on 4in green PVC, not laminated yet. Anyway, I only could get 1-2 inches off the toroid. It was pitiful, the best when the primary was tapped all the way out at 16 turns. Any less it just got even worse. But, i took the toroid off, and flipped the thing on with no topload- just the wire sticking out the top. It took off making 9-10 inch streamers! MUCH better, but purple and spindly. Anyway, it STILL did best using all 16 turns! I think i need way more primary turns since the more i used the better it got, I think if i had more the toroid would do well also. Is this because a 28 gauge coil has so much inductance? I am led to believe so. Also the size of my cap, should it be bigger or smaller? One last question. My NST has no RF kickback protection, but i am not running it much as of right now. with ~15 second run times do i have anything really to fear? Thanks a million for all the help from this list and all other lists! =Rockinriley14=
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Re: 4 inch coil - - First light!!
Posted by Bert Hickman on 7/21/2004, 10:13 pm, in reply to "4 inch coil - - First light!!" --Previous Message-- Hi, The probem is that you don't have enough tank capacitance to bring the system into tune. A small tank cap will result in thin, spindly sparks. In order to get fatter sparks and bring your system in tune with the existing number of primary turns, you'll need to add at least another 7-10 bottles in parallel with your existing beer bottle tank cap. If your system runs at 15 kVAC without blowing holes in the beer bottles, great! If you start punching holes in the bottles, you'll need to use pairs in series. Good luck and play safely! -- Bert --
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