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Re: Tesla frequency

Hi Jeremiah,

	Tesla coils operate at a given frequency much like radios do.  The
"frequency" refers to the number of times the voltage changes from
positive, to negative, and back in one second.

Tesla coils have two tuned circuits (the primary and the secondary) that
must both operate at the same frequency.  

The primary circuit is formed by the primary capacitor and the primary
inductor.  The primary circuit frequency is calculated by:

Fo = 1 / (2 x pi x SQRT (L x C))

Where:

Fo is the frequency in Hertz (Hz) or cycles per second.
pi = 3.14159...
SQRT is the square root function.
L is the inductance (measured in Henries) or the primary coil.
C is the capacitance (measured in Farads) of the primary capacitor. 

The primary capacitance can usually be read or calculated from the value
printed on the capacitor :-)  If it is a salt water or rolled poly cap then
it gets tricky.  A simple LCR meter is best but given enough information,
we can get close...

The primary inductance can be found from the formulas at (Archimedes Spiral
Coil Inductance):
                                                               
http://home.earthlink-dot-net/~electronxlc/formulas.html


The secondary coil and the top terminal also oscillate at a frequency also
given by:

Fo = 1 / (2 x pi x SQRT (L x C))

However the secondary's capacitance is a tricky to determine just by
calculation.  The coil has it's own capacitance that adds to the terminals
capacitance in a complex way the defies simple equations.  The program at:

http://users.better-dot-org/tfritz/site/programs/E-TESLA5.ZIP

will figure it out.

The secondary inductance formula can be found at (Helical Coil Inductance):

http://home.earthlink-dot-net/~electronxlc/formulas.html

This URL is a gold mine of great formulas as is the main site:

http://home.earthlink-dot-net/~electronxlc/

When making a coil, it is important to try and figure out the frequency
before you build it so that you can try to get the primary and secondary
tunable to the same frequency.  We often hear of the "coil won't make
sparks" problem and find that the coil's primary and secondary frequencies
are far off.  It is best to try and get the frequencies figured out in the
first place to avoid having to make major modifications later to get the
coil to tune.  When in doubt, copy someone else's coil that works really
good. ;-))

Hopefully, this is what you were asking.

Cheers,

	Terry




At 03:07 PM 5/29/00 -0600, you wrote:
>I was wondering what is meant by the frequency of the coils.  How do you
>find the frequency via formulae
>
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