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Re: Top Toroid
> Date: Fri, 31 Jan 1997 23:15:56 -0700
> From: Tesla List <tesla-at-poodle.pupman-dot-com>
> To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject: Re: Top Toroid
> Reply-to: tesla-at-pupman-dot-com
> Subscriber: FutureT-at-aol-dot-com Fri Jan 31 23:09:47 1997
> Date: Fri, 31 Jan 1997 11:08:23 -0500 (EST)
> From: FutureT-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: Top Toroid
>
> In a message dated 97-01-30 03:33:50 EST, you write:
> >snip
> ><< One quick remark. try to construct the cap with the least amount of
> > metal just a thin shell of metal is best (aluminum duct tape on 4 pvc
> > joints fitted together works well) The reason being is that the top cap is
> > also in the midst of the magnetic field that is set up by the primary ind.
> > If the terminal cap was a solid chunk of metal, the changing magnetic
> > field would set up an E field in the cap and induce current flow causing
> > heating of the Terminal cap which is a waste of energy. you don't want the
> > toroid to soak up the energy of the magnetic field you want that energy to
> > be soaked up by your secondary coil.
> > There is a good toroid home brew description on Bill Beaty's Tesla
> > web page.
> > enjoy!
> > --Bert S.
> >>
>
> Interestingly, toroids (even thin metal ones) get quite warm when used on a
> tube coil, at high power levels.
> John Freau
John,
EVERYTHING in the proximity of a high power tube TC gets warm.
Several mechanisms are involved which include the infrared heat
coming off the tubes and other components. The human body in
proximity to the operating coil will enjoy some dielectric induction heating effect
like a diathermy machine produces. The smooth walled aluminum topload toroid
will get warm from heat conducted throughout it (thermal conduction)
from the very intensely hot point where the output streamer is being launched
from, just the same as if you played an oxy-acetylene torch on one
spot. As aluminum is such a good conductor of heat the entire toroid
will very nearly equalize in elevated temperature in a room without drafts.
Is this the cause of the heating effect you have observed and refer to?
I suppose a second cause which would be much lower in effect could be due to
some I2R heating in the aluminum since the circulating currents are quite high in
these bigger machines when a topload is employed.
Also, if you use microwave oven transformers, they get really hot
too! : ( It's a darned shame, since iron is so inexpensive and the
most abundant commodity on our planet (next to human stupidity) that
microwave oven transformers are deliberately made with undersized
cores to magnetically saturate, thus making these transformers far
less than ideal for us coiler's needs.
rwstephens