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Re: [TCML] first light

Hey-- A toroid or any top electrode will light up with corona when the electric field at its surface is about 30 kV per cm. For a sphere, the E field at the surface is voltage/radius. For example a sphere with a 10 cm radius will light up at 300 kV or above. A cylinder will require twice the voltage to get the same E field, so a 10 cm radius cylinder will light up at 600kV. The field at the surface of a toroid is a little lower than that of a cylinder, but not much. So we would expect a 7x30 toroid (8cm radius x 37.5cm radius)to turn on at 30kv/cm*8cm*2 = 480kV, or about 0.5 MV. When this voltage is reached, many dancing streamers will suddenly appear. Using toroids or spheres like this is a good way to measure the voltage. 

---Carl






Hi Bob,

36" isn't at all bad for first light.  I'm sure mine was considerably less
when I first started out.

I didn't see any reference to what your tank capacitance is?

Your experience matches mine as far as varying power to the sucker gap
motor.  You don't need ridiculous amounts of airflow when the air is
perfectly channeled in a sucker gap.

Terry filter resistors WILL get very hot - that's normal.

I've never been able to get the streamers to dance smoothly around the top
load.  It may be that my 7x30 toroid is pushing the limit, but I have to use
a breakout point.

You're only drawing 4-5 Amps to the NST at 140V?  Hmmm, I typically pull
20A+ to my 15/60, and that's *with* PFC caps.  If your cap is seriously too
small, that could explain it.  Or if your main gap was much too narrow?

Regards, Gary Lau
MA, USA



On Fri, Jul 8, 2011 at 7:51 AM, robert massa<massahbob@xxxxxxxxxxxxx>wrote:


     Started tuning sgtc. 15k60ma nst with 150mf pfc caps, terry filter
,pri- 15 turns1/4 copper tube pri 1/2 on center pancake primary tapped at
121/2 turn,  sec- 4.25x 22.25 wound with26g mag wire,  bottom turn at top
edge of pri plane,  top load 3.5"x12.5" with 6"x23" toroids stacked on top
of each other, both are homade ductwork smoothed and covered with very
smooth burnished foil tape, bottom of the top load is even with top winding
of pri.  Switching with sucker gap is similar to Gary Lou with 1" diameter
hollow smooth brass electrodes, seems to work the same if vac motor is 1/2
or full power on dimmer swich control.
      Tesla map design says should get 50" to grounded target.
    Set safty gaps on TF and main gap acourding to instructions.
     So far 36" strikes from break out point to grounded target.
    1)  The resistors on t filter get warm, but saftet gaps vaven't fired ,
is this heat normal ?
    2)  Will not discharge with uot a break out point, even pushing 140v and
4.7- 5 amps input to NST. Why ?  Not enough capacitance ?
     3)   Would like to see streamers dancing around toroid instead of break
out points, am I being unrealistic with this set up ?                 Still
trying to figure out how to get pics and short vid clip posted.  Thanks for
all the info from forum so far, Bob
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