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Re: Operating Frequency

Original poster: FutureT@xxxxxxx

In a message dated 7/11/05 2:04:31 PM Eastern Daylight Time, tesla@xxxxxxxxxx writes:


Hi All!

What´s the best operation frequency for a tesla coil ?
Wich factors should I to consider when choosing the operating frequency ?

Thanks,

Tiago Ventura 


Tiago,

One factor is the physical size of the coil.  Large coils tend
to run at lower frequencies simply because the large secondary
tends to have a high inductance.  It seems that if the frequency
is too high some efficiency may be lost.  Usually I try to
keep the frequency below 500kHz although it's doubtful
that any differerence would be seen compared with for
instance 700kHz.  Many folks have built mini-coils which
run at one or two mHz and they work OK.

I like to use quite a few turns on my secondaries, perhaps
1100 to 1600 turns.  This helps to keep the frequency low.
Of course a larger toroid lowers the frequency too.  Usually
folks don't really give much concern to the frequency.  Instead
they decide how long they want their sparks to be, then work
backwards and pick a toroid size, secondary size, wire size,
primary size, tank cap value, power supply, etc.

If you're designing for a given power supply, then you'd work
the other way to see what spark lengths can be obtained,
and then figure as above to determine the other components
mostly using rules of thumb that work well based on
experience.  Select proper LTR values for NST's if you're
using them, etc.

John