Re: Grounding Problem???

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Esondrmn-at-aol-dot-com>

In a message dated 1/24/02 6:14:35 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes: 


>
> Hi John, Scot, All 
> > 
> >     I have tried loosening the coupling quite a bit.  To get rid of the 
> > racing sparks the coupling must be around 0.08.  Spark length is pitiful 
> > in that case.  I have tuned the coil as well as I can.  The tuning point 
> > is about 1.5 turns in from the calculated point.  Moving the tap just 
> > decreases spark length.  I am running a 6 inch coil using two of those 
> > GE copier xfmrs for a supply.  I'm using a 0.1 uF cap, for a bang size 
> > of approx. 5 joules.  My specs are in the "Help! suicidal secondary" 
> > thread, except that I'm now using a smaller toroid of 6" by 22".  I 
> > tried a 0.066 uF cap, but racing sparks remain.  Spark length goes in 
> > the toilet too.  On a good humid night, I can get a few 6 ft. strikes to 
> > the ground.  Dry nights give short streamers, and long racing sparks 
> > :-(.  I can't believe that I could be overpowering an epoxy coated 6 by 
> > 28 inch secondary with 1600 VA. 
>
> It is not a power problem but an energy one. 5J is developing too 
> high a voltage for a secondary that size (and length in particular). 
> I'm getting 5'+ from a 4' tall secondary using around 4J/bang and not 
> a hint of racing sparks. Not only is the taller secondary able to 
> handle higher voltages but it is developing lower voltages for the 
> same energy as well. 
>
> Regards, 
> Malcolm 



Malcolm, 

I have a similar sized secondary, 6" diameter with a winding length of 27.6"
using 22 guage wire.  I am using a .05 mfd cap with a 14, 400 volt transformer
running about 7 kva.  If I did the math correctly, the bang size here is 11
joules.  This coil runs fine with a sync rotary at 240 bps.  If I try to run it
at 120 bps, I get a very intense and visible corona between primary and
secondary, with small sparks coming out of the middle of the secondary, and it
looks like it is ready to blow up.  In order to run at 120 bps, I would need to
reduce my coupling to be safe. 

Ed Sonderman