Thanks for the suggestions! I will probably end up making my second coil a
four inch one like the one you suggested, but for now I want to see how
efficient I can make a tabletop coil so that I can make the rest of my
coils as efficient as the tabletop one. I am on a low budget, so I will
make a vacuum gap until I can afford a SRSG. the calculations I have used
say that an .0088 uF capactior is best, so I was wondering if an .01 uF
capacitor would be OK. Also, my local Home Depot doesn't sell 2" aluminum
ducting, so I was wondering what material i should use for the toriod.
Finally, where could i get all of the parts for the Terry Filter?
Thanks again!
Blake
Chesscactuar@xxxxxxxxx
Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: FutureT@xxxxxxx
In a message dated 12/13/04 12:49:24 AM Eastern Standard Time,
tesla@xxxxxxxxxx writes:
>Hello, my name is Blake Hartley, and I am a new member to this group and I
>have finished my first coil. The specs are as follows: 9kv 30mA NST,
>.0075mF party cup capacitor, 6 turn flat primary (ID 3" OD 9", .25" soft
>copper tubing, .25 inch spacing), 1.86" secondary wound with 785 turns 29
>AWG magnet wire (coating), and 1.5" radius spherical topload. I could get
>2.5" sparks from it tapped at the end of the primary. I built a new 8 turn
>primary, same as last but 11" OD, so I could get the correct resonance.
>Right when I finished the primary, my secondary came apart somewhere, so I
>must make a new one, which I plan on coating with polypropylene so it
>doesn't fall apart. I was wondering if I should make the same secondary
>again or if I should redesign it. Any suggestions would be much appreciated.
>
>Thanks
>Blake Hartley
Blake,
Congratulations on first light of your coil. A 9/30 NST can
give about 20" sparks or so in a somewhat near optimal design.
I'd suggest using a 3.5" or 4" dia secondary about 15" or 19"
tall, using 1200 - 1400 turns of 29awg magnet wire. The capacitor
should be an LTR value such as 0.02uF. A small synchronous
rotary gap will get the best results from the system. In any
case a good spark gap is very important even it's a fixed
multiple type gap. Use a safety gap and Terry filter to protect
the NST. The toroid should be 3" x 10" or so. A 2" x 8" toroid
would be OK too, and should give multiple streamers. For a
small coil like this, 10 or 12awg insulated wire can be used for
the primary, or the copper tubing can be used, but will need
quite a few tu rns. You can calculate the number of primary turns
needed by using Bart's JavaTC program. You can see my
TT-42 coil which gives 42" sparks from a 12/30 NST at;
http://hometown.aol.com/futuret/page3.html
Click on the link for spark gap coils. There's also information
on tube coils, rotary gaps, a SRSG phase shifter, toroids, etc.
John
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