RE: [TCML] Pictures of my Tesla Coil

["Dirk Stubbs" <dirk@xxxxxxxxxxxxxx>]

Thanks for the input. I have an additional neon transformer(15KV @ 30mA)
so I can just hook them up in parallel to gain the 60mA. I will also try
raising the primary 1" as you suggested. I would love to gain 30-36"
sparks from it but I do have a question. If you look at my primary I
have a safety ground ring(to avoid the sparks from hitting the primary)
that is about 2" above the primary which is about 20" from the toroid.
If the coil could deliver 30-36" sparks, why wouldn't it not just hit
the safety ground ring which is closer? Excuse my ignorance. 

Anxious to try once the weather clears up in Kansas. I am not confident
with running the coil in the house as I have alot of computers and
afraid something bad will happen. Call me a chicken I guess. :) 

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Barton B. Anderson
Sent: Sunday, December 23, 2007 3:31 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Pictures of my Tesla Coil

Hi Dirk,

Thanks for the specs.

Tuning looks good. Your about 4% high on inductance which is where I 
like to be. Coupling was slightly low at k = 0.11. You could probably do

some coupling adjustments if you can raise the primary or lower the 
secondary. A k of 0.13 is when the primary is about 1" above the 
secondary. The coil probably won't like going beyond that.

The coil could probably do about 30" to 35" spark length. But power is 
low with the 30mA supply. A 60mA or 90mA supply would certainly help on 
this coil.

These coils can handle rather high power with no problems as long as you

keep racing sparks away. About 5% more primary inductance above the 
resonant tune point is good to help with this especially when power is 
increased. The other item is to keep coupling high but not so high that 
racing sparks occur. Also, if high powers are used (say greater than 
100mA transformer), you have to keep an eye on the lower secondary 
windings as they can begin to burn. I run a very similar coil but I had 
to lower coupling due to the bottom sec turn burning (no racing sparks, 
just burning). The transformer is a 12/60 NST with 1/2 the shunts 
removed. Since I fixed that I've done some rather long continuous runs 
on the coil (20 to 30 minute runs which is extreme for a coil, but it 
just keeps on going).

Here's some photo's of that coil for reference.
http://www.classictesla.com/photos/ba45/ba45.html

Take care,
Bart




Dirk Stubbs wrote:
> Sorry I should have included some details.
>
> Power: Neon Transformer 15KV @ 30mA
> Capacitor: 14 doorknob capacitors 30KV @ 590pF  = 8.2nF
> Secondary: 4" PVC with 22" total winding of 24-28 gauge(Don't remember
> the exact gauge but do recall it was about 1000 turns)
> Primary: 1/4" copper tubing, 13  turns, 22" overall diameter,
> approximately 3/8" spacing(5/8" center to center), currently tapped at
> 11
> Toroid: 2 - 8 pie pans with 4" flexible duct.
>
> When I originally built my coil, I used TeslaMap to determine what I
> needed.
>   
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