Re: Ferrite Rod + Tesla Coils = Woah!

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

Original poster: "harvey norris by way of Terry Fritz <twftesla-at-qwest-dot-net>" <harvich-at-yahoo-dot-com>


--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Neil Richardson by way of Terry
> Fritz <twftesla-at-qwest-dot-net>"
> <neil-at-opticalrealities-dot-com>
> 
> The other day I built a small tesla coil in 1 hour,
> it is VERY badly built:
> 5 primary turns, 200~ secondary, very small. It
> works, very poorly, but it
> works, so thats kinda a startm enuf to help you
> understand one. I tuned it a
> bit, and managed to get a 5mm arc to 10mm. Someone
> then told me that putting
> a ferrite rod in the coil would improve its
> performance, after all, i'm
> using a flyback for power with a 12V 1A supply.
> 
> Guess what? I now get 1" arcs when I put my finger
> near to the thing! Its
> not really a tesla coil now, but its good for 1
> hours work and with very
> limited materials! I salvaged every part from
> broken/working devices and
> boxes full of stuff I forgot to unpack 3 years ago.
> I would like to post
> some pics, but sadly my camera needs new batteries,
> ill be sure to post some
> when I get some new batteries for it.
> 
Can you state the dimensions of secondary compared to
dimensions of rod? What type of ferrite? Plastic
bonded ferrites are common with rf chokes. The ferrite
I have experimented with is ceramic,Sr Fe in
unmagnetised form. It will only give a 50% increase of
inductance with core insertion on multiturn wound
coils tested. It is only when the total loop of flux
is encompassed with ferrite, as in a transformer core,
that the higher values of flux appear, thus the
relative increase of a measured coils inductance is
not dramatic at 50% for simple core insertion.

The conductivity of SrFe ferrite itself is highly non
linear. See Impedance measurements of a magnetised Sr
Fe Wafer.

http://groups.yahoo-dot-com/group/teslafy/message/97
Because ceramic materials have a dielectric capacity,
the 480 Hz AC inputs available from a converted
alternator do produce appreciable currents through
those materials noted as "190 volts enabling 78 ma
magnet current." (In the highest conductivity test.)
The magnets as a load between phases, with their
nonlinear resistances to applied voltages actually
change the circuit from being series resonant to
parallel resonant as the rotor field DC voltage is
increased.

Because we initially assume those to be currents of
capacitive reactance, a scheme to use that SrFe
component itself for a 480 hz resonance was tried.

All of the ferrite conductions appear only to be due
to LEAKAGE REACTANCE, with no speculated capacitive
reactance in comparison. This was easily determined by
using a 1 nf ferrite sample in series with 60 henry
coil. The ferrite only acts as short, allowing only 
the minimal coil conduction, also when  placed inside
coil sample.

More questions then evolve, where it is then supposed
that since the currents are not capacitive, they might
be tested also as inductive reactances.
Ferrite Currents Tested as Inductive Reactance.
http://groups.yahoo-dot-com/group/teslafy/message/105

11 inch ferrite cylindrical capacity exibits high freq
as magnetic effect.

http://groups.yahoo-dot-com/group/teslafy/message/102
If the currents are solely resistive, we might expect
the heat to be uniformly dissipative. However only one
end of the rod will show heat. Additionally coils
placed around the rod show the existance of a high
frequency standing wave, localized on the position  of
sensor coil to that on the rod.

Sincerely Harvey D Norris








=====
Tesla Research Group; Pioneering the Applications of Interphasal Resonances
http://groups.yahoo-dot-com/group/teslafy/

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