RE: [TCML] Intro and questions

["Lau, Gary" <Gary.Lau@xxxxxx>]

Hi Paul:

I assume you're talking about the secondary dimensions?  The lower limit would be governed by when the coil's sparks coming off the top load would be too close to the primary and just hit there.  The upper limit is more difficult to define.

You're right about the number of turns and aspect ratio.  I have found that bigger is almost always better, sometimes being bigger than what is "typical" for a certain power rating.  Being big forces the secondary, and conversely, the primary, to have high inductance values, which is believed to minimize losses in the spark gap.  It also forces lower frequencies which tend to have lower losses.  For my 4/20 NST-powered coil, I found a significant performance gain by going from a 1.9" dia to a 4.2" dia secondary.  Only the pri & sec coils changed, everything else stayed the same.

There no doubt is an upper limit, relating to when the secondary capacitance becomes so high that the given power level can't charge it to the point of breakout.  But I suspect it would look aesthetically silly before you get to that point.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of dunnsept
> Sent: Friday, December 07, 2007 1:28 PM
> To: tesla@xxxxxxxxxx
> Subject: [TCML] Intro and questions
>
> Just a quick introduction:
>
> My name is Paul, I've been doing some of the "introductory" HV stuff like Jaccob's
> Ladders, & ignition coil spark drivers etc.
> now it's time to move on to tesla coils. I've been reading as much as I can online
> and trying to seperate the wheat from the
> chaff. I hope that once I get up to speed, I can then reciprocate and help others.
> I live in Michigan and work as a computer programmer/network admin.
>
> ok, on to the questions! (knew that was coming, didn't you)
>
> I have a franceformer 9kv 30mA nst I will use for my first coil. I've read online about
> the range of sizes appropriate for use
> given a particular input. What are the parameters for the choice though? How do I
> decide if I should use say 2 inch versus 3
> or 3.5? I don't have any of them available at home, I only would have 1" PVC so I
> have to purchase PVC or what-have-you
> regardless. I also do not have  anywhere near enough wire so I will wind up
> purchasing that too. The wire choice, as I understand
> it should be such that for whatever size form I have, I should get 800 - 1600 turns
> with a winding/length ratio of about 5:1 (correct?)
>
> thanks for your input/feedback to help this newbie get started  ;-)
> (for what it's worth, even though I'm not particularly well versed in some of these
> aspects, I'd rather learn what I can about it rather
> than have someone just give me a shopping list)
>
> tia
> Paul...

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