Re: Tesla Coil Operation - was "Harmonics"

To: tesla-at-pupman-dot-com
Subject: Re: Tesla Coil Operation - was "Harmonics"
From: "D.C. Cox" <DR.RESONANCE-at-next-wave-dot-net> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Tue, 02 Feb 1999 19:15:11 -0700
Approved: twf-at-verinet-dot-com

to: Antonio

The best way to feed a magnifier is to make the driver a series fed
resonator as well.  Just feed your primary tap across approx 20-40 turns of
1/2 inch copper tubing (keeping the Q as high as possible), and then the
copper tubing continues as either 2 AWG welding cable or Litz wire (2-4
AWG) on up the form.  Use a fiberglass water tank as a form (relatively
inexpensive from Farmer's Cooperatives used as water and pesticide spray
tanks --- easy to obtain in diameters up to 6 feet.  This format will give
you a 100-200 turn driver with a very high Q that will provide a very
powerful base current to the bottom of your resonator coil.  

The primary/sec of the driver is all one series element with the low side
at ground potential and the power fed into the tap as required to achieve
the proper resonance in your resonator inductor.  The resonator inductor
can be fine tubes of magnet wire, but the driver pri/sec system must be the
best possible Q to generate the very powerful peak currents necessary to
operate the resonantor.

Also, you want to keep the k factor of the driver around 0.6 if possible to
couple the greatest possible amount of energy into this system.

Regards,

Dr.Resonance-at-next-wave-dot-net

----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Tesla Coil Operation - was "Harmonics"
> Date: Monday, February 01, 1999 11:43 PM
> 
> Original Poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> 
> 
> Tesla List wrote:
> 
> > If k=sqrt(L1/L2) then L2=L1/(k*k): for L1=13uH and k=0.2 --> L2=0.32mH.
On
> > the other hand, If I just reconnect my secondary I get
> > k=sqrt(13uH/29mH)=0.02. It looks like the whole secondary needs to be
> > recalculated or the primary needs to be bigger.
> 
> This circuit really appears to require relatively large primaries if k
> is
> to be kept at about 0.1. As sqrt(L1/L2) is also the inverse of the
> voltage 
> multiplication ratio of the circuit, the ratio is limited to about 10,
> requiring high input voltage for long output sparks. This may be the 
> fundamental reason why the transformer version is preferred.
>  
> > Does this lead to the second coil (tighly coupled to the primary)
typical
> > of 3-coil magnifiers?
> 
> The magnifier could be another way of building this circuit with lower
> input voltage. The function of the transformer would be then to increase
> the voltage at the base of the main resonator.
> 
> Antonio Carlos M. de Queiroz
>