Tesla HV Coil

[TheCell]

Hello

it's somehow kapanadze related.(delamorto)
THe secondary of a Tesla Coil is the primary of a kapanadze coil operated through a spark gap.

Please check my assumtions whether they are correct or not
and complete them if necessary.

This setup meant to establish a standing wave with a 0 V Node and a Lambda / 4 position with max elongation at the other end.

Is it (when operated through a spark gap) allways a quarter wave, or a half wave or multiple of a whole wave so that there are  2* n maximums that are achieved.

The frequency depends only on the number of turns.

In the circuit diagram the 10...300 pF cap imho is used to retune the L1 to resonance if a load is applied (bulb).

So there is the spark gap in series. Can it be a resonant LC paralell tank through the spark gap ?

[darkspeed]

The L1 + 10kv cap + spark gap is a tank.

The spark gap when ionized becomes a conductor for the duration of the arc.

There will be many cycles exchanged between the capacitor plates through the L1 before the ionized spark gap collapses.

The 10kv cap ( and the inductance, capacitance of L1 ) sets the primary frequency.

The spark gap allows a charge to build in the 10 kv cap so there is enough stored energy to excite the primary.

[bboj]

If this is a Tesla setup than the length (and not the number of turns) on secondary plus primary depends on f of lc circuit.
This way you also determine where you want points of maximum excitation - at one end lambda/4, at the both ends lambda/2.

[TheCell]

@darkspeed: confirming my thoughts

@bboj: I am missing the basics. (or at least understanding only partially)

Assuming that there was only one coil with one end grounded, the other fed by a sparc gap and no capacitor.
There would be a standing wave of Lambda / 4 by definition.
Is there a formula for determining the resonance freq. of a coil in the above mentioned configuration.

If having a load on the secondary the tank circuit comes into action helping maintaining the standing wave.
Having the frequency, measuring inductivity L of the coil and getting C via the classic LC Tank resonance formula. f = 1/( 2 * Pi * sqrt( L * C ) )



Can someone point out to sources that are related to creating standing waves and the resonance frequency of the coils . On the secondary is only a load put on.
Why does the sum of the length of both coils have influence on the frequency and not only the primary.

Does this reflect to the design of the secondary.

[darkspeed]

You have to look at the L1 as if the spark gap was not there

What will affect the L1 frequency

Capacitance and inductance of the 10kv cap
Capacitance and inductance of the L1 coil
Capacitance and inductance and proximity of both of the L2 coils
Inductance and Hysteresis of the core material

Take a look here for some of the basic equations.

http://deepfriedneon.com/tesla_frame6.html

It is always slightly off from calculations and requires empirical adjustment