RE: [TCML] VTTC geometries, opinions needed

["Jim Mora" <wavetuner@xxxxxxxxx>]

Hi Bart,
Yes for some reason I plugged in 19awg. I gather from what you say the
frequency will not be effected too much with a plate top which was the goal!
With heavy build the total turns would be 925. I need to find my micrometer
and mic the wire to be more accurate. Is worse case 925 turns enough??
Jim

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of bartb
Sent: Monday, September 07, 2009 9:58 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] VTTC geometries, opinions needed

Hi Jim,

The old 9.1 toroid 20% reduction is not correct for a small disc plate. 
I personally would not use such an old tool. Your better off simply 
measuring Fr or upgrading to the latest Javatc. With the new Firefox 
browser (3.5.2), the default coil runs on my pc (Vista) in 0.9 seconds 
and 0.7 second on my laptop (Xp).

Something is bugging me however. Why only 755 turns using #21 for 32" 
length? You should be nearer to 1030 turns for typical magnet wire and 
at the very least 925 turns for the extreme heavy wall wire. The typical 
1030 turns for a close-wound 32" length using #21 with your plate would 
drop Fr down to 258kHz or so. I'm pretty sure this is not what your 
intending and wanted to point out the above.

BTW, my vttc sec has been wound. It's 4"D x 20.5"L, #24 on acrylic 
tubing. It will be shielded with a small toroid giving Fr at about 350kHz.
http://www.classictesla.com/vttc/vttc%20winding%20003.JPG

Also, making this an oil filled coil.
http://www.classictesla.com/vttc/vttc%20tube%20001.JPG

Take care,
Bart

Jim Mora wrote:
> Hello Coilers,
>
> I am planning a quad 833C @ 4KW and have most of the goodies now (I have
> been rat holing for several years). For the secondary former I have a 36"
> .125" wall 6 inch acrylic tube. I want to wind it with 32 inches of #
21awg
> 200c wire. That amounts to 755 turns at 23.6 turns per inch. The coil
should
> have a self resonance of 367.35hz. For a top load and more for shielding
> there will be a 7" .25" (rounded edge) plate which gives a total resonance
> 328khz using -20% with Javatc 9.1. Is that an error? I want to stay near
the
> coveted 350khz resonance point.
>
> I have a few concerns: is 755 turns enough? I chose the wire to keep Fo up
> there and still have some coil height.
>
> The primary will be an eight inch acrylic .125 tube with a sliding grid
> feedback coil. The secondary (the unwound part) will go through the deck
to
> be able to adjust the coupling on s screw of some type.
>
> I am under the impression the primary to secondary coupling should be
close
> to k=.22 what is the max? 
>
> There will be 1" vertical HDPE wind standoffs around the primary former
and
> the winding will be 3/16 soft copper tubing spaced .2". So the primary is
> actually 10". The feed back coil will be above the primary and be 8" in
> diameter.
>
> I plan to use a total of .004uf mica cap array that gives about 15 turns
of
> the primary. This gives a mutual inductance of about 220 and an inductance
> of ~59uh.
>
> The primary will be cool if it doesn't are over (which I think is
unlikely)
> as it can be tapped the classic way.
>
> Any concerns or critics welcome. I will start the project this winter.
>
> Dr Spark, you are using a 2awg primary, yes? That is counter intuitive to
me
> as I think we want higher impedances to match the high impedances of the
> tubes. What am I missing there? Having (4) in parallel surely helps this.
>
> My test transformer can deliver 10KVA at various voltages with a target FW
@
> 4500v but weighs in about 200lbs. Good for setup and testing though!
>
> Thanks
> Jim Mora
>
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>
>   
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