Re: [TCML] Primary Turns

[mddeming@xxxxxxx]

Dear Kiwi,

The "Magic Number" is a balancing act given by the ratio:

L1 x C1 = L2 x C2

L2 is the inductance of the secondary coil and is therefore a "fixed" value for a given secondary coil..
C2 is the capacitance of the secondary and is the sum of the internal capacitance of the coil plus the effective capacitance of the topload and streamers. This varies with the size and type of top load
C1 is the tank capacitance and is usually picked to be 1.4 to 2 times the value that would resonate with the power supply, depending on the type of spark gap, and for any given transformer may also be considered a "fixed" value. 
L1 is the inductance of the primary and is the one highly adjustable parameter, ther other being the size and elevation of the topload.

Upgrading to a larger transformer requires a larger tank capacitor, and if the topload is to remain the same, larger C1 means smaller L1 (fewer turns). If the topload is made larger but the power supply stays the same, then L1 must be larger (more turns) If L1 becomes too small, high in-rush currents increase stresses on the system, but if L1 gets too big, then performance falls off since, as an upper limit, 
V2(max)= V1 x SQRT(L2/L1)  
This is why L1 is made adjustable, with more turns available than the program may show that you need for one particular configuration. 



Hope this helps,

Matt D






-----Original Message-----
From: andrew <andrew@xxxxxxxxxxxxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Sun, Jan 31, 2010 5:45 pm
Subject: [TCML] Primary Turns


 Hi all
Is there any minimum number of turns that the primary can be.
 am using Javatc with a theoretical primary cap of 0.067 uF and the program
s suggesting
about 4 turns. Is this right as I thought it needed about 11 turns. Most of
he coils I have seen pics of have about a dozen turns or so? 
I am trying to figure what size cap / no of pri turns to use with my already
uild secondary. I guess I am just wondering if there is some ideal no of
urns or cap value
hile still achieving resonance of course.
Cheers
iwi Newbi
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