RE: Voltage determination

["John H. Couture" <couturejh-at-worldnet.att-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Bart -

It is a well known fact that the secondary coil inductance affects the
length of the output spark. This is the main reason that 1000 turns are used
instead of 100 turns for a Tesla coil. The 1000 turns gives more inductance
and longer sparks. Of course there are many other design considerations. The
theoretical equation is
   Vs = Vp sqrt(Ls/Lp)
Note that when Ls is increased the secondary voltage Vs is increased which
in turn increases the spark length. The factor I used is non linear and
obtained from empirical data and using mathematical regression.

Empirical Tesla coil design is a complex combination of many parameters
involving both theoretical and empirical equations. The Tesla coil output
spark length equation is obtained from empirical data and subject to many
variations.

John Couture

--------------------------------

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, July 25, 2000 11:13 AM
To: tesla-at-pupman-dot-com
Subject: Re: Voltage determination


Original poster: "Barton B. Anderson" <tesla123-at-pacbell-dot-net>

Hi John,

Couple questions below:

Tesla list wrote:
>
> Original poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>
> How about using the following equation that takes in the most important
> conditions that affect the output spark? One advantage of using factors is
> that you do not need to know the efficiencies. The factors are based on
> empirical data.
>
>   Spark length = W*Vp*Ls*B
>
>  W = Input watts
>
>  Vp = Factor for Tesla primary volts
>
>  Ls = Factor for secondary inductance
>
>  B = Factor for breaks per second
>
> The JHCTES program uses a similar equation.



How is the secondary's inductance important to spark length? I can see it's
importance to Fr, but not to spark length (power processing maybe?).
Inductance
is a factor that naturally increases with coil size - size generally means
more
power applied and therefore greater spark length. Is it possible that
inductance here is mistaken as a factor due to naturally occuring mechanics?
Maybe not, I just haven't seen a reason Ls would be thought of as a major
factor to spark length, and if it is, I'd like to know why?

The equation would suggest just increasing Ls to gain spark length. I'm sure
you didn't mean the equation in that way. Maybe you are referring to a
higher Q
secondary?

Thanks,
Bart