[TCML] Pictures of my Tesla Coil

[Barton B. Anderson]

Hi Dirk,

When you raise the primary and if you see racing sparks, start coming 
down in small increments until their gone. You may very well end up 
where you started. This arena will always be trial and error. One coil 
might handle 0.13 just fine and another coil may need 0.1. If it works 
out that 0.1 is your coils value, then so be it. But, do give some 
higher coupling a try.

Sparks will hit the strike ring from time to time, but they will also 
seek out the field around the toroid itself. I personally no longer use 
a strike ring. I got tired of strikes hitting it. Once I removed it, I 
had fewer strikes down to the primary area and more strikes in the air 
(this was most apparent as I increased power).

However, if a strike does run down to the primary, it can cause problems 
with the NST. So strike rings are certainly helpful to prevent unwanted 
voltages back at the transformer. I decided to risk it and this has been 
my personal preference for a few years now. So far so good. The TCML 
recommendation is still to use a strike ring.

Take care,
Bart

Dirk Stubbs wrote:
> 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 at pupman.com [mailto:tesla-bounces at pupman.com] 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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