Re: Please help!

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

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi Ronnie,

I think your questions all depends on what you want to do. The 4 NST's 
could be farmed for 1800VA (nameplate). That would make a "goodly" supply. 
However, regarding what it is you want to do, I'm referring to the 12 turn 
primary. Assuming I some assumptions were correct on my part, I would show 
the Fres for the loaded secondary about 246 kHz. To use all 12 turns on the 
primary would require a tank cap value of .01uF.

I'm not sure what C would be for one of your 6x6 plate caps, but I figured 
ideally at .0266uF. So 2 of these in series would yield .0133uF or 3 in 
series would yield .0088uF. Have you measured the capacitance? That would 
be a good idea given these are plate caps. I would recommend something in 
the range of .0133uF which would allow a little less inductance than 12 
turns, meaning you will have room for fine tuning the coil and still use 
most of the turns on the primary. It should be noted you will be running 
smaller than resonant (STR) as opposed to Resonant or LTR:

Yes, the spark gap and safety gap should be placed across the transformer:

View with fixed width font:

                                           " OOOOO "
                                               +
         NST                       Cap         S
-------+    +--------+------+-----| |-----+   E
|      |    |        |      |             P   C
|      p    |        |      |             R   O
+      p || s        |      o             I   N
A      p || s   Main o       Safety       M   D
C      p || s    Gap o       Gap          A   A
+      p || s        |      o             R   R
|      p || |        |      |             Y   Y
|      |    |        |      |             |   |
-------+    +--------+------+-------------+---+
        |                                      |
       --- MAINS                             ----- RF
       /// GROUND                            / / / GROUND

Take care,
Bart


Tesla list wrote:

>Original poster: Ronnie Pittman <r3pittman-at-yahoo-dot-com>
>hello all,
>It has probably been about 5 years since I last run my tesla coil and my 
>memory is very bad.  Since then I have moved and the only things that I 
>kept were the secondary, the spark and safety gap, and the toroid.
>
>I am planning on trying to set up another coil for an Educational day my 
>school is having monday morning ( I am a high school science teacher) and 
>I am having a hard time remembering all the details.
>
>I have made a new primary for this coil out of 12 turns of  3/8 copper 
>tubing spaced 3/8" and at 30 degrees to replace the old one which was a 
>cylindrical one made form 10 ga wire.  I also just finished a new cap made 
>from 24 plates of 6X6" aluminum seperated by 4 sheets of 4 mil poly.  I 
>have 8 of these banks submerged vertically in a tank of transormer oil 
>with taps coming out the side that I can wire in any fashion.  The 
>secondary is made on 4"pvc drain pipe and is 973 turns of 24ga wire.  The 
>toroid is 2 pie plates and dryer duct.   As for transformer, I have 4 good 
>15 kv 30 ma nst's, and one PT rated at 1kva.
>
>My questions are as follows, If my calculations are correct, for 1 of the 
>nst I would need to run four of the caps in series?  Should I try to use 2 
>nst or possibly the pt with a welder in series and if so any suggestions 
>on what to put the welder rating at?  Also If I remember correctly, the 
>spark and safety gap are parallel to the transformer and the cap is behind 
>the spark gap in series on one leg going to the primary? Also anything 
>else I should use to protect the nst?
>
>Any and all help would be greatly appreciated.
>Thanks
>Ronnie Pittman
>
>
>
>