RE: [TCML] first coil help - BartB

["Thomas Ryckmans" <thomas.ryckmans@xxxxxxxxxx>]

Hi Bart,

What should I know about k? Is it, roughly, the ratio of energy transferred
from primary to secondary? I have Mitch Tilbury's "The Ultimate Tesla Coil
Design and construction guide", but while there are equations to calculate
k, I still don't know exactly what it is...
Shall I aim for a k as high as possible?

Am rewinding the primary as per your instructions but it is going slowly
(making a new base, a new set of primary support, a way to vary the height
of the primary wrt the secondary) - I wish I had more time...

Many thanks

Thomas

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of bartb
Sent: 24 March 2008 03:02
To: Tesla Coil Mailing List
Subject: Re: [TCML] first coil help - BartB

Hi Thomas,

No problem. Thanks for letting me know. Certainly makes a difference and 
your numbers now do end up at 15 turns/cm.

Something I noticed however, the distance from the bottom of the 
secondary to the edge of the beginning of the primary looks to be about 
5.5cm which is wide and makes for a low coupling of 0.08 along with the 
primary about 1cm below the secondary? I would recommend raising the 
primary to where the primary is 3cm "above" the secondary which would 
put k at 0.123. That seems extreme, but it's not with your geometry. 
Should tune in at about turn 3. It would be nice if you could use a few 
more turns out of the 8.4 you have now, but due to the situation you 
really can't. Normally I would say get rid of all those extra turns as 
it is a little extreme, but the fact is those extra turns add some 
external C to the coil and allows more turns to be used. So I would just 
leave them alone for now.

It would be nice to rewind the primary if possible starting the primary 
at about 2 to 2.5 cm away from the secondary and then setting the pitch 
to 13mm (center to center) or basically where the spacing edge to edge 
equals the wire diameter. No need to have such large spacing between turns.

Spark gap needs some work, but you already know that.

Take care,
Bart


Thomas Ryckmans wrote:
> Bart,
>
>  
>
> Really sorry to have wasted your time; the diameter of the secondary is 70
> mm not 130 mm. 
>
> Using the inductance calculator here
> http://deepfriedneon.com/tesla_frame6.html
>
> I get 3.2 uH with Diameter=70 mm, 480 turns, 15 turns/cm, 32 cm height
>
>  
>
> Really sorry
>
>  
>
> Thomas
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
>   
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