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Congratulations on you finds! I'd recommend making your secondary coil form at least 24" long, and make the secondary winding about 22" long. Close the secondary - you'll have about 1500 turns, and you'll need about 0.8 pounds of magnet wire. Buy a 1 pound spool of new wire and try to buy "double build" or "heavy" insulation. This type uses 2 coating layers. Before winding the form, make sure that you sand off any black lettering or stipes that might be on the PCV pipe, since this is often electrically conductive. A good topload can be made using flexible dryer duct and a couple of pie pans or small pizza pans. I'm going to assume you us 4" diameter dryer duct to make a toroid with an outside diameter of 18"-20". The combination of the secondary with the topload will resonate at around 152 kHz. Instead of chokes, I'd really recommend using a pair of 500 - 1k 50 - 100 watt wirewound power resistors instead on each leg of the NST HV outputs. These resistors should be the type that are wound on a ceramic form and not the type that are housed in a metal case for heat sink mounting. HV chokes have been found to cause more problems than they solve. I'd recommend making your primary using 1/4" copper tubing, and I'd also recommend a flat primary for ease of construction and better clearance to the secondary. Use 1.5" spacing all around the secondary (~7" inside diameter) and 1/2" - 3/4" turn-turn spacing, and use at least 17 turns. This will require about 100 feet of 1/4" tubing. You can also use bare copper grounding wire (available in the electrical section of your hardware store). Assuming you tap the primary at turn 15, the primary inductance will be about 97 uH. To get the primary circuit to resonate at ~152 kHz, you'll need about 0.011 uF of tank capacitance. Note that this is about 2X the size that some Tesla Coil design programs will recommend. The larger capacitor size is called "Larger Than Resonant" or LTR. Using a LTR tank cap will help prevent accidentally overvolting your NST if your main gap misfires (you still need safety gaps thoguh!). Assuming you use 12 oz beer bottles (~800 pF/bottle) and you connect pairs in series, each series pair will provide about 400 pF. To get 0.011 uF you'll need two cases of beer bottles... hope you're thirsty! :^) Hope this helps and good luck with the coil! -- Bert --
--Previous Message--
: YESSS! I aquired a NST yesterday! it cost me $25 from a sign shop in St.
: Joesph, MO. It is a 15/30. I also liberated a couple of pieces of 4"
: green PVC pipe by the road. Should make for a pretty typical coil.
: If I use #28 wire, about how many inches of windings will i want on that
: 4" PVC? i will be using a flat primary (maybe conical) and a RQ-style
: gap, safety gap, and chokes.
: about the chokes-- i have two leftovers from my old setup, about 6 inches
: of winds on 1/2in pvc, i want to say about 26-28 gauge. Are these
: sufficent chokes to protect my neon transformer?
: I plan to build a beer bottle cap for it, how many beer bottles will I
: need? I think they will need to be in sets of two for a 15Kv source, is
: this correct?
: Any other suggestions for this coil would be appreciated. It will be a
: pretty typical coil setup so I believe other people have probably done
: this. Thanks in advance for any advice!
: =Rockinriley14=
:
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