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Registered Member #3885
Joined: Sun May 15 2011, 12:47AM
Location: Newton, Massachusetts, United States
Posts: 94
I've managed 5" to 6" sparks from a 555 timer-driven flyback coil before, and although the experience was highly rewarding (it was my first coil), the coil itself wasn't all that impressive and I was left longing for more. Even though my VTTC's spark length was only about an inch longer, the thick, sword-like sparks were more interesting and the whole system had more potential for experimentation with things like voltage doublers, staccato, and modulation. My VTTC directly lead to my work with solid state coils, and it's only recently that I have been experimenting with spark gap coils again.
Hey every one, I am making a SGTC using a spare 15kv 30ma francformer my local neon sign shop gave to me. Following deep fried neon guide I figured that a 4 inch diameter 20 inch long would be suitable for my nst. But is it really needed? Would a 10 inch long 4.5 in diameter secondary with about 800 turns of 28 magnet wire work just as well? I just want to design this sobthat I can get as close to the calculated 3 foot sparks as I can.
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
TeslaCoil wrote ...
Hey every one, I am making a SGTC using a spare 15kv 30ma francformer my local neon sign shop gave to me. Following deep fried neon guide I figured that a 4 inch diameter 20 inch long would be suitable for my nst. But is it really needed? Would a 10 inch long 4.5 in diameter secondary with about 800 turns of 28 magnet wire work just as well? I just want to design this sobthat I can get as close to the calculated 3 foot sparks as I can.
I was reading some TCML archives the other day, and it appears to get your Freau number as near to 1.7 as possible you want your secondary surge impedance to be between 40 and 80K. A 10" secondary will suffer from flashover issues. Also, don't hijack other people's threads!
I apologize!! I just figured that since the original poster and I had the same rated transformer he might find value in that information as well!! Sorry everyone!
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
It's fine, I don't mind, I think we're following the same guide. Anyway, you need a taller secondary so you don't strike the primary and fry everything.
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
Alright, I have most of the primary circuitry completed, and I was wondering if someone might be able to point me in the right direction to calculate the peak current in the primary, because I realized the peak currrent for the caps I'm using in my mmc is 80A, only one string, so want to make sure I don't fry them after a couple mS.
Also, how long can you run a spark gap made of carriage bolts before they vaporize?
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First SGCT, questions
