RE: resonant freq

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

The typical frequency of a coil varies by the size of the coil.  A small
1.5" diameter table top coil might operate in the 400-800KHz range.  A
larger 4" diameter coil might operate in the 100-200KHz range.  In general,
one should strive for the lowest possible frequency, as circuit losses are
less with lower frequencies.  In practice, the power supply sets the upper
limit to the size of the tank capacitor, and the total power through the
system sets the upper limit to the top load size, so these things set the
lower limit on the operating frequency.  1.5 MHz is do-able, but unless you
are talking about a very small coil, you would do better with a lower
frequency.

The secondary resonant frequency is not determined by the length of the
wire.  This is an old and widely-believed misconception.  The frequency is
determined by the inductance of the coil, the physical dimensions of the
secondary, and the size of the top load (toroid) connected to the top of
the secondary.

The use of chokes to suppress kickbacks is another thing that was once
widely believed.  Current research, simulations, and thinking now suggests
the use of R-C filters in place of chokes.  See
http://www.laushaus-dot-com/tesla/protection.htm and
http://hot-streamer-dot-com/TeslaCoils/Misc/NSTFilt.jpg

Regards, Gary Lau
MA, USA

>Original poster: "divyarajdesa by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<divyarajdesa-at-satyam-dot-net.in>
>
>hi all
>i am a newbie as far as building tesla coils are concerned. i would like to
>know this....what should be the range of resonant freqs of the coil? i know
>this freq is determined by the length of the wire used. but is it ok to use a
>resonant freq of about 1.5Mhz. would the chokes withstand the kickback? 
> 
>thanx
>raj