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Re: help
> Now drill a small hole each end of the PVC about 1/2 inch
> from the top and bottom. Shove one end of the wire thru one
> of the holes and leave about a foot of wire on the inside.
> Take some tape and put it over the wire so you don't pull it
> out like some dummy I know did (me). Now comes the winding...
Don't ever make this mistake. I learned the hard way. Drilling
holes and introducing wire inside of the coil form are lethal
errors. While the coil may function fine with a CW or solid state
driver system, when properly excited in a Tesla tank circuit the
coil will fail internally. Now with this "candlestick" design
advocated by the author you will never be able to properly couple
the coil to a Tesla tank circuit (due to the high aspect ratio)
IF you could if would short out through the inside of the tube.
Richard Quick
... Quoting Brent Turner:
> Richard -
> Couldn't help but jump in here a sec -
> Every coil I have built using the 'pass-the-wire-through-the-hole
> technique seems to work fine!!! One coil has a winding length of only
> 13", and would toss out 14" sparks religiously. Even my large 3.5KVa
> coil uses this method...it's secondary has a winding length of about
> 25", and throws a really hot 65" spark!!!!! (I did cheat a bit with
> this coil though by placing two plexiglass insulator disks internally
> on the secondary coil form. (10" dia, grey PVC ducting)
Even baffles do not work when you max out a coil design and are putting
out 3 to 3.5 times the winding length in spark discharge. This is not
really a sound practice IMHO.
> Try putting a blob of RTV around the wire on the inside of the
> coil form.
Been there. Done that. I have blown out baffles. Blown through RTV
sealant (layered even), blown through coil form sidewalls. When you
squeeze a bunch of inductance into a fairly small unit volume of
coil form the resonator geometry becomes quite potent. The problem
then becomes one of redesigning the construction to prevent internal
breakdowns while removing the need for internal baffles.
Quite simply: while you have not had this problem, many others have.
The best solution I have found was the one Richard Hull suggested:
Never allow the wire inside the coil form. Since adopting this
method I have had zero secondary failures. I have not had any
complaints from any others who build with this construction tip.
Ed Sonderman has a 22 inch long secondary winding, has good photos
out here showing 72 inch point to point strikes: no baffles.
RTV silicone sealant produces high concentrations of acetic acid
vapor during the curing process. When used to seal baffles inside
of a secondary coil form the trapped gas ionizes readily. I did
this once with a clear plastic coil form and you could see the
glow from the inside of the coil when the system was energized,
prior to the big glow that ended the short life of this coil.
The baffles failed.
> Besides, there's little difference between arcing from the top
> winding to the bottom on the inside OR outside.
I don't know about that... When they fail internally the coil
forms are generally arc scored and the coil is ruined. When they
fail externally I just put a larger toroid on the top and fire
again with no apparent harm done.
Richard Quick
... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12