Re: Tesla coil output voltage

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi JT,

The top of a Tesla coil acts much like a large capacitor.  If you 
short it to ground, the current is "very high" since the resistance 
is low compared to the voltage.  The current would be:

I = V / R

Where:
I is the current
V is the voltage
R is the resistance in the current path.

If we have 250000 volts and 10 ohms, the current is 25000 amps!  But 
usually the resistance for a very fast arc is sort of high.  Wild 
guess would be in the thousand amp range for a short to ground.

There is a secondary current during the coil's operation.  This 
current is not the same along the secondary due to capacitance of the 
secondary to ground.  But if we don't look too close, that current is:

Is = Vs / (2 x pi x Fo x Ls)

Where:

Is is the peak secondary current
Vs is the top peak voltage
pi is 3.14159...  (3.00000... in Indiana :o)))))))
Fo is the coil's operating frequency
Ls is the secondary coils's inductance

An example would be:

Is = Vs / (2 x pi x Fo x Ls)

Is = 250000 / (2 x 3.14159 x 150000 x 0.050)  ===  5.3 amps

This current is usually somewhere in the 10 amp range +- on order of 
magnitude or two.

Cheers,

        Terry


At 06:19 PM 11/26/2005, you wrote:

> I need to know, for sure, what my coil produces.(voltage & current)
>
> I can tell you all humidity, spark distance, breakrate of topload, 
> and resonant frequency of secondary, and much more.
>
> * currently its about 70% humidity
> * my topload breaks out at 210 Hz
> * unloaded secondary is 240KHz
> * maximum spark distance is 15.5 inches
> * topload is 10.5 inch diameter toroid, 3.5 inches thick
> * topload is semi-smooth Aluminum air ducting w/ foil tape all over it
> * no clue about output current
>
> can you tell me, with this informartion what the output voltage is? 
> Current would be nice too, but il need to measure that one somehow.
>
> Borne coiler,
> JT Bowles
>
> _