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[Fwd: Re: It works, But I want more. (fwd)]



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In a message dated 97-03-04 00:17:21 EST, you write:

<< Thanks to everyone for helping get my first coil off the ground.  
 
 Especially Mike Hammer and Bert Pool, who helped and helped and
 helped.
 
 Ok, here are the specs:
 
 corcom rf ac filter
 
 5a variac
 
 9kv x 30ma (I have another 9 x 30 and two more 12 x 30; just limiting
 exposure to stupidity)
 
 1/2" spark gap
 
 2" pvc x ~100 turns 22 ga. chokes
 
 1 1/2" copper tube x 7  -at- .028" spark gap w/ muffin fan
 
 60" x 14" x .093ldpe rolled cap (.007995 uf per my Radio Shack meter)
 
 12" id 3/8" +  3/8 clearance  x 10 turns 30 degree spiral primary
 
 6" clear acrylic tube x 24" (~900 turns) 22 ga. secondary
 
 5" x 12" drain pipe toroid (I know it's small but nothing happens with
 the big one.)
 
 8 ' ground rod w/ 8ga. ground wire to base of secondary
 
 I get:
 	blue 15" streamers into air (they don't photograph well)
 
 	occasional 15" white streamers to nearby grounded objects
 	
 	a few lines of interference on tv
 
 
 I noticed that the primary works best wide open.  Any reduction of 
 windings reduces output. Do I need a bigger primary coil or 
 jus mo juice?
 
 I'm ready to try some of these other transformers. 
 
 I know I can strap xformers of equal value, and that's next 
 
 Now don't laugh, I can't help that I don't know any better.  
 What about strapping all 4 of my neons together:
 
 ----------------*|||*---------------	
 		*|||*
 		*|||*
 240vac	   ~140	*|||*12kv 30ma * 2
 	    vac	*|||*
 single  |-------*|||*-----|	=~21kv -at- 60ma
 phase   |		  |
         |-------*|||*-----|
 		*|||*
 	   ~100	*|||* 9kv 30ma * 2
 	    vac	*|||*
 ----------------*|||*---------------	
 
 
 of course, even if it worked, I'd need another capacitor in series.
 
 
 All comments and suggestions are badly needed.
 
 David Christal 3341 Cloverdale Lane, Dallas, TX  75234
 214 349-6972 (214 FIX MY PC) (Pool Cues and Personal Computers)
  >>

David,

Sounds like a good project, about the same as my 6" coil.  I did some
calculations on your coil.  Your are correct, you are just on the edge of
being in tune.  I calculate the correct tune for your given parameters would
be at turn 10.5.  If you remove the toroid or use a smaller one, you should
be able to tune it now.  You need a .0088 mfd cap to tune it as described.
 The best bet, if possible would be to add two turns to the primary.  This
will give you some room to add the larger toroid.  You might also consider
building another capacitor and using the two in parallel.  I am glad to see
that you used .093 poly (instead of .063).

The inside dia. of you primary seems unusually large to me.  You have allowed
3.0" clearance from the secondary.  I think my primary is 2.0" (I.D.) larger
that the secondary O.D. - allowing 1.0" clearance.  Of course my coupling was
too tight and I had to raise the secondary up 2 or 3" to fix that.  I doubt
if that is costing you much in output.

I use a .025 mfd cap, 14 turn primary (tuned about 13) and a 40" toroid.

You can parallel as many transformers as your variac can handle but they must
all be the same voltage rating.  With a 5 amp variac, you will probably need
to add a power factor correction cap across the primaries if you use two or
more in parallel, to keep the variac current as low as possible.

With the two 12kv transformers in parallel, and the system in tune, you
should be able to get about 3 foot sparks.  This coil should perform well and
scale up just fine as you desire to add additional power.

Ed Sonderman






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