Re: 10 Questions to help me construct my first TC

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Michael,

At 08:07 PM 12/13/2002 -0800, you wrote:
>I am going to construct a Tesla coil my son can do tests on for his science
>project
>and I need help.

Thanks dad ;-))  Science fair season must be upon us now :-)))

>I am new to this.  I have read a lot and I have learned a lot.
>But there are still several gray areas about how to make an efficient TC.
>
>I have tried several programs, excel sheets and java scripts.
>Most all of them help me decide on the tank capacitor(s) to use
>or how many primary turns I will tap at.
>But they don't answer several questions that I need help with.
>
>I want to create the longest good looking spark I can with my 7.5Kv 30ma
>NST.
>
>The software does not say which ratio gives the longest spark.
>Some people say to use a 1000 turns.
>But John Freau's efficiency theory says to use about 1600 turns.

It really does not matter all that much.  "Around 1200 turns" works just 
fine.  Basically, just whatever you end up with.


>I read things like: "spark length (inches) = 1.7*sqrt input power (wallplug
>watts)"
>But doesn't the size of the TC have something to do with the length of the
>spark?

John's formula you mention is really great!  "Power is proportional to 
spark length" really is the key regardless of many other things.  You are 
looking at 15 to 20 inch arcs as the formula says.


>So can you guys help me?  I would like to know how to build this thing.
>I would like to get a variety of opinions and I guess I will just go with
>the consensus.

Yes ;-))


>Power supply is set: 7.5Kv 30ms NST and I am using RQSG.

Oh!  Sure... Make it easy...  From the tables at:

http://hot-streamer-dot-com/temp/MMCcapSales.gif

You want 15.9 nF or ten of the Geek Group caps.


>1. Secondary wire gauge?

I use #24 for everything unless you have some other close gauge at hand.

>2. Secondary diameter?

Greater than 4 inches.  Like 4.5 to 12 inches...  Not real important but 
the larger the diameter, the larger the inductance you need to tune the 
primary circuit to.

>3. Secondary turns?

800-1600 seems to be "popular"

>4. Primary wire gauge?

"i" like that 1/4 inch tubing, but you could get away with 10-12 gauge 
house wire here.

>5. Primary coil ( flat, helix or inverted cone(angle?))?

Go with flat.  No reason to make the primary an "engineering feat".

>6. Toroid cord diameter?

Go to the big hardware store and get the biggest aluminum flex tubing they 
have.  "That" is automatically the perfect size ;-))

>7. Toroid diameter (please specify OD or center to center)?

Find those cheap pizza pans at like Target.  They are "automatically" the 
perfect size too ;-)

>8. Tank capacitor value (should I trust the software?)?

15.9nF +- like 10%

>9. Primary turns (should I trust the software)?

Trust ye software...

>10. Static gap ( gap space and number of gaps)?

With an LTR cap as recommended, the largest gap that can fire 
reliably.  Trial and error depending on your particular gap "stuff" there.

Cheers,

         Terry



>Thanks for your help.