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SGTC mathematics help

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watchingthenight

Sun Mar 30 2008, 10:01PM

Registered Member #904 Joined: Mon Jul 16 2007, 03:15AM
Location:
Posts: 7

CORRECTED

Hi,

I am producing my first SGTC and have doing the math but I am unsure if what I am finding is correct seeing as how

I have no experience. So far by using the Javascript Tesla Coil Calculator I have been able to determine:

Transformer:
15kv 30mA 500000 Impedance and .00531 Mf Resonant Capacitor

Secondary Coil:
3577ft of wire 69khz resonance

Cap reactance:
sec coil resonance: 69Khz Reactance: 434.783 Inductance for primary: 1002.867 mH

Now while all of this math makes sense I'm not sure if the numbers I selected for the secondary are appropriate. Using the spark length equation then my max length theoretically is 36.1" and so I assumed that my secondary should be about 25 AWG Cu wire, 3577 feet is what I have at hand for the AWG.

Any tips would be immensely appreciated, also I am not looking for instructions for construction, I have produced circuits in the past and know what I am doing I just lack knowledge in this field in terms of what parts to use. I am basing my ideas off this schem in case anyone is wondering,

Also, I was wondering how should I go about increasing the spark length, I would like something over 8'+

Kizmo

Sun Mar 30 2008, 10:05PM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

Take a look here

Coronafix

Sun Mar 30 2008, 10:22PM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

What size secondary are you going to use?
Nice transformer by the way.

watchingthenight

Sun Mar 30 2008, 10:27PM

Registered Member #904 Joined: Mon Jul 16 2007, 03:15AM
Location:
Posts: 7

@kizmo thanks for the link I'll look through it

@Goldsphere I don't understand what you mean do you mean in terms of length of the pipe or amt of wire or something else?

I'm thinking something like this for the secondary

do you think it would be appropriate?

Ultra7

Sun Mar 30 2008, 10:43PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

I use Teslamap.

You just plug in all your values and it tells you where to tune.
It has a MMC calculator and other goodies.

Also, where did you ever find a 15K/200mA Transformer?
Is this a NST with the shunts removed, or is it some special build?

When we say "what size is your secondary," we usually mean the outside diameter of the tube and the winding height.

watchingthenight

Sun Mar 30 2008, 11:08PM

Registered Member #904 Joined: Mon Jul 16 2007, 03:15AM
Location:
Posts: 7

CORRECTION: the transformer is 15kv but at 30mA not 200mA that was a mistake by me I just double checked it so I'm sorry for misleading anyone. I did update the first post for anyone who takes a look.

Thx for the tesla map thing I am going to try it out. the size of the od on the sec coil is going to be 6in and the height 4ft but I'm unsure if these are good ideas

Coronafix

Mon Mar 31 2008, 12:41AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

30mA....oh
I was gonna say, i've never heard of a 200mA NST before.

You are probably better off with a 3-4 inch diameter secondary
with a 5 or 6 : 1 winding ratio.
That ebay secondary looks nice but the person obviously doesn't know much about
Tesla coils, I'd suggest wind your own.

bob golding

Mon Mar 31 2008, 12:49AM

Registered Member #1084 Joined: Mon Oct 29 2007, 08:58PM
Location:
Posts: 28

to get 8 feet of spark you are going to need around 3 kw input power. you can do this with 4 MOTs and a static gap if you keep run times short. the secondary will need to be around 10 inches long and 5 foot tall. you want around 60 nF of cap for that. good luck with the small one.

watchingthenight

Mon Mar 31 2008, 01:00AM

Registered Member #904 Joined: Mon Jul 16 2007, 03:15AM
Location:
Posts: 7

when you say 5:1 ration I assume you mean Secondary to Primary but what should be the form and height do you think? (I'm trying to solve this on my own but I'm still pretty lost)

Ultra7

Mon Mar 31 2008, 01:29AM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Ratios mean your secondary diameter, by winding height.

A 4 inch coil (4inch = 4 to 4.5 outer diameter) would do well with a 5 to 1 ratio to a 4.5 to 1 ratio.
Meaning. . .
4 inch OD (Outer diameter) to 20 inch winding height. with about 24 gauge Magnet wire.

That SUPER Secondary on Ebay probably would be impossible to tune without ridiculous primary turns.

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