Re: High Voltage Output

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Chris,

On 1 Jun 2004, at 11:37, Tesla list wrote:

 > Original poster: "Chris Fanjoy" <zappyman-at-hotmail-dot-com>
 >
 >    As someone relatively new to this hobby (still building my first
 >    TC) I
 > haven't fully grasped all the principles involved. One thing that has
 > me puzzled is this: what determines the high voltage output of a Tesla
 > coil? If not the step-up ratio of the coil itself, then how about:
 > -Firing rate of spark gap

No.

 > -Size of tank capacitor

Partly

 > -Operating frequency of coil

No

For a disruptive (i.e. capacitive discharge) coil, the fundamental
relationship based on the principle of conservation of energy is
Vout = Vgap * SQRT(Cp/Cs) where Vgap is the voltage the gap fires at,
Cp is the primary capacitor value and Cs is the total secondary
capacitance.
      A rider has to be added to this by saying that the voltage only
gets there if the secondary is not allowed to break out (i.e. emit
sparks) which is true for all types of coils.

     For a CW coil, the output can be much higher if the coil is not
allowed to break out and is governed by the effective shunt
resistance of the secondary such that full output voltage is reached
when the energy fed into the primary per cycle is equal to the
secondary shunt losses per cycle. For this reason, most CW coil
designs limit the number of cycles that can be fed to the primary and
encourage the secondary to break out at a voltage that does not
compromise the secondary insulation and/or allow pri-sec flashovers.

Malcolm

 > -All of the above?
 >    Just curious, as this may be something to consider as I design my
 >    own TC.
 >
 > Chris
 >
 >
 >