Re: A Little more than general questions II

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

Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-uswest-dot-net>" <ghunter31014-at-yahoo-dot-com>

Hi Wade,

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Wade B AndB Anderson by way of
> Terry Fritz <twftesla-at-uswest-dot-net>"
> <nabedaw-at-juno-dot-com>
> 
> Hi guys,
> 
> Again , Thanks for all the input on my last
> questions.
> 
> I'm wondering if one of you has a formula for
> calculating the
> inductance??? The one I have requires that the
> permeability of the core
> be included. And since this device has an air
> core............maybe the
> permeability is  1???

The inductance of a 12" x 30" coil wound with 22AWG
magnet wire is about 120mH.  The permeability of air
is 1.

>   I am also working on another project that I
> requires me  to calculate
> the inductance of my coils, but these coils have
> iron and steel cores,
> and permeability information must be top secret or
> something, cause I've
> been unable to locate it.
>  Anyway, back to TC's
>    I had previously asked how the diameter of the
> secondary affects the
> operation,.......and I think Greg you mentioned that
> the operating
> frequency will decrease with an increase in
> diameter??? Now the Tesla
> coil is very dependent on the frequency being
> high??? Correct??? So,
> increaseing the diameter will increase the "Q"
> point, which is a bad
> thing, the lower the Q the closer to (theoretical)
> true resonance???

all other things kept equal, a fatter coil has a
higher Q than a skinny coil.  That's a good thing, not
a bad thing.  With an appropriately sized top load,
your 12" x 30" secondary wound with 22AWG would
resonate at about 70kHz, which is as good a frequency
as any.  You would need about 3500 feet of wire to
cover 30" of coil form with 1100 turns. I agree with
your assessment that it will be a "dandy".  Such a
secondary could be the basis for a very high
performance coil system, capable of running at
pole-pig power levels.  6 to 8 foot or even longer
sparks would be possible with a big enough power
supply.

>    I'm hung up on this diameter thing because I have
> a 6 ft piece of 12"
> diameter PVC, and I'm debating to whether or not I'm
> going to build my
> first coil with it, and it will be a dandy. Using
> #22awg -at- 1,000 turns
> will take up about 2 1/2" feet. I'll probably save
> that piece of plastic
> for a later coil.
> 
> 
>   It seems that the spark gap needs to be adjustable
> while the coil is in
> operation.

I've never built a spark gap that is adjustable in
operation, so I can't advise you on that one.  Sounds
like a lot of trouble for not much gain, but that's
just me.

> 
> What are some SAFE methods of constructing an
> adjustable spark gap??? I
> have some ideas, just looking for other input.
> 
> And also, what are some reliable materials that can
> be used at the spark
> gaps terminals???  Brass??? Carbon??? Water???
> Something that won't melt
> down.

I use regular copper plumbing pipe and fittings from
the hardware store.  My sparks gaps seem
indestructable, even at pole pig power levels. Go
study the big sucker gap on my web site. While you're
at it, link over to Gary Lau's site and study his neat
hardware store sucker gaps. You can spend big bucks on
Tungsten rod if you want to, but you don't need to.
Brass and Copper electrodes have given me years of
excellent service.


> Thanks again,
> 
> Wade

Cheers,

Greg
http://hot-streamer-dot-com/greg

>  
> 
> 
> 


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