Re: [TCML] Stuck at 36"

[Bert Hickman <bert.hickman@xxxxxxxxxx>]

Hi Bill,

If I calculated it properly, your overall tank capacitance is somewhere 
around 0.038 uF, and your NST bank is faceplate rated at 7.5 kV at 180 
mA. The optimal tank capacitor for this configuration (when using a 
static gap) would be about 1.6 times the "mains resonant" capacitance 
(0.064 uF) or about 0.1 uF.

The reason you're hitting a wall is that you're being "power limited" by 
the relatively small size of your tank capacitor. Your "bang size" is 
presently only about 1/3 of the optimal size. Thus, at a given break 
rate, the amount of power that can be delivered by your coil's primary 
circuit (i.e., bang size x break rate) is also only about 1/3 of what it 
could be with the proper size tank cap. So even though your NST bank has 
the capability to deliver longer sparks, your tank cap does not.

I'd recommend adding about 0.07 uF MMC to supplement your existing 
capacitor bank, or replace the homemade caps entirely with a 0.1 uF MMC 
bank to save space.

Bert
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b.jbohn@xxxxxxxxxxx wrote:
> Hello everyone, first time here (great site!).  I've built a coil
> that refuses to put a streamer past 36" to a grounded plate suspended
> vertically at the top of the secondary.  Occassionally I'll get one
> 41-42".
>
> I'm using NST's 1@60Ma 7.5kv 4@30Ma 7.5kv all hooked together.  I
> think they're all okay because if I remove any one of them from the
> system performance diminishes.
>
> The secondary coil that I've had the best luck with is wound on a
> 5-1/4" varnished paper tube winding length 22-1/2" the wire is .014
> or #27 magnet it's 1,607 turns 2,208 feet.
>
> My capacitors are a mixed batch of homemade HDPE plate type.
>
> Caps #1 & 2 each contain aluminum plates 10 x 12" 16 plates each .090
> HDPE between each plate
>
> Caps #3 & 4 each contain aluminum plates 4-1/2 x 9" 40 plates each
> .060 HDPE between each plate
>
> Cap #5 rolled type in oil .01583 MFD
>
> All capacitors are in oil.
>
> My spark gap is a segmented type with 10 copper tubes 7/8 OD 5" long
> total space between gaps is .150" just enough so the transformers can
> break. The gap is also blown with a fan.
>
> My primary is a 1/4" copper tube conical 15 degree 14 turns 23" OD
> 7-1/2" ID seems best tapped at 12 to 13 turns.  I'm using a spun
> toroid it is 4-1/2 x 18" that size seems to work the best although if
> I put a 6" sphere on top pretty cool stuff happens (the streamers
> jump around the toroid and ball).  I have other secondaries that I've
> tried but this one is the best.  I have looked at other coils on this
> listing and other websites and I think mine should be doing better
> than 36".  Any input appreciated!
>
> Bill _______________________________________________ Tesla mailing
> list Tesla@xxxxxxxxxxxxxx 
> http://www.pupman.com/mailman/listinfo/tesla


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