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LAN_403

Self Defenestrate

Wed Sept 27 2006, 05:22AM

Registered Member #87 Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191

Alrighty. So I've finally decided to build a new coil. It will be powered by a 9kv 60ma neon, and I have alot of questions. Rather than open a series of threads, I'll lump them into this mass thread.

1. Suggested cap value is .0176, and I'd like to use 942C's (have access to 11), but the closest I can come is either .0187 using eight caps, or .0166 using nine. Would it be better to be a bit higher, or a bit lower than the suggested value?

2. For the spark gap, I was planning on using a series of brass hex heads, maybe four 1/2" heads for three gaps, in a sealed box with a small fan blowing through them. Will this be enough to take the heat and quench the gap properly?

3. I'm really strapped for cash, and I'll need a decent amount of 24awg for the secondary. I remember people sampling some wire from Essex, how would I go about doing that? I see that the sampling thread in the archives has been shortend.

4. I understand the basic differences in flat versus conical primarys, but at the power i'm pumping, is one going to be much better than the other? How can one figure that out, short of moddeling it in something?

Thats all, for the moment.

Michael W.

Wed Sept 27 2006, 02:20PM

Registered Member #50 Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324

When I tried to sample for essex they got really angry and told me they didn't have time to waste on a student....

Part Scavenger

Wed Sept 27 2006, 03:55PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

1. With a Neon, I would say a little smaller to avoid overloading the Xformer.
2. Prolly.
3. If you find out, tell me! I never figured that out either. Maybe they don't do it anymore. You can find a decent amout of wire in large degauss coils from TV/Monitors (It's usually #26) if you're hard up.
4. I'd run scantesla to determine the best uH value for your coil, then if you want to go conical, you would increase the "steepness" of the cone until it hits the maximum coupling you think your coil can handle. If you experience arcover or interturn sparks, raise the secondary until it stops.

Terry Fritz

Wed Sept 27 2006, 04:30PM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi,

1. I would go higher but it does not matter much.
2. Sould be fine.
3. E-bay.
4. Flat primary is fine.

Cheers,

Terry

Marko

Wed Sept 27 2006, 05:18PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

24AWG looks _thick_, for that transformer I would consider some 0,2..0,3mm wire. Try digging around old relays, induction motors, degauss coils etc. (I do mostly), usually 0,1mmwire for mains relays but thicker can also be found..

Self Defenestrate

Thu Sept 28 2006, 03:49AM

Registered Member #87 Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191

Really? Smaller wire? I was going with the suggestions of the "deepfriedneon" pages, which point to 24awg wire, 4.5"OD pvc, 22.5"wind length. I geuss I'll search ebay for some wire. Having the lower capacitance for my tank cap would add another 2kv of voltage to the overall rating, and possibly make the neon last longer, sounds good to me. I'll start with a flat primary, and slowly try raising it conical as per some internet calulators.

Part Scavenger

Fri Sept 29 2006, 02:43AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

You'd probably be fine with something as small as #27. And a flat primary is probably just fine. Sorry if I'm copying you Firkragg, but I don't have a clue as to metric sizes.

Tetrafluoroethane

Sun Oct 01 2006, 02:12AM

Registered Member #127 Joined: Fri Feb 10 2006, 03:36PM
Location: Cincinnati, OH - USA
Posts: 44

Chances are you are going to get good results that won't depend much on your wire size. For example, my first coil used a 15KV 30ma NST and 8nF tank cap. Using a static spark gap w/o forced air quenching I was able to get 36.5" strikes to ground. I had a 4" PVC primary wound with about 1000 turns of 22ga wire. All done on the cheap and worked like a dream.

Now to actually give my answers to your questions:

1) I found a smaller tank cap to be better than a larger one. Too large and your spark gap firing rate drops below 120Hz (for 60Hz line) and you end up beating the crap out of your tranformer (I think that is referred to as resonant charging). NSTs tend not to like that.

2) I opted away from brass since all I could find was brass-plated nuts. I used 1" copper pipe with reducing couplings stuck in each end (I found the kind that goes inside the pipe instead of on the outside). I had about 8 gaps, though I don't remember the spacing currently. Each reducing coupling sat in a hole bored in scrap plastic. Worked great and stayed cheap. Use your imagination for how to connect your wires.

3) I find Electronics Goldmine to be a decent source of magnet wire. That is where I got mine. I think they sell it by the pound. I got an 11 pound roll and have wound 2 secondaries for my coil. I have enough left I could wind about 4 more. Go for a small roll and you will be fine.

4) I used a flat primary. And even then I had too much coupling and had to raise the secondary above it by several inches. Your mileage may vary, but I would go with a flat for your power level.

Good luck.

Self Defenestrate

Sun Oct 01 2006, 05:18AM

Registered Member #87 Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191

Cool. I can get solid brass bolts, so no worrys there. I figured they would be easy to replace when they get crummy. I'll just find some cheap wire and work it out from there.

Part Scavenger

Sun Oct 01 2006, 05:07PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

I got my wire from Kelvin.com. It used to be the cheapest around, but now it's up with the rest of them. However, they often do sell it in smaller amounts than Goldmine.

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