Re: dual MOT Tesla coil design is complete (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "resonance" <resonance@xxxxxxxxxxxx>


I was referring to our large Big Bruiser coil which produces approx 
28 ft long spark with 27 kVA input.  This also applies to our model 
M-150 coils producing an 8 ft spark running at 7.5 kVA.

It depends also on the potential a coil achieves which varies with 
the inductance which of course varies as the square of the radius of 
the coilform.  Big Bruiser is 24 inch dia while the M-150 is only 18 inch dia.

As you pointed out this value is lower for smaller coils.  There is a 
lot of waste in larger coils and the spark gap is the usual suspect 
for excessive waste.

I won't know exactly until we get this 4.8 kVA IGBT coil up and running ---
perhaps sometime in Jan.   Brian V. is going to borrow a bunch of 
parts from me and work on it while I'm gone this winter.  He is also 
experimenting with Peltier effect cooling on the IGBTs to eliminate 
the normal heatsinks and fans.

Dr. Resonance



> What is this 1kw per foot of spark for classical coils???  It has 
> always been a sqrt(power) and not a linear relationship, has it not?
>
> BTW, my 2KW (real wall power) classical coil generates over 7 foot 
> arcs. So this would make it 285 watts per foot by this reasoning, yes???
>
> Gerry R.
>
>
> > Original poster: "resonance" <resonance@xxxxxxxxxxxx>
> >
> >
> > with IGBTs the rules are changing.  Their much higher switching 
> > efficiency and lower losses of heat and light lead to 450 Watts / 
> > ft of spark performance as opposed to 1 kW / ft required in classic coils.
> >
> >
> > Dr. Resonance
> > ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> > To: <tesla@xxxxxxxxxx>
> > Sent: Wednesday, November 01, 2006 5:59 PM
> > Subject: Re: dual MOT Tesla coil design is complete (fwd)
> >
> >
> > > Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> > >
> > > Hi Terry,
> > >
> > > This would be great, but what ever happened to the sqrt(power) 
> > > relationship???
> > >
> > > Gerry R
> > >
> > > > Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
> > > >
> > > > At 10:48 PM 10/30/2006, you wrote:
> > > > > Hi DC,
> > > > >
> > > > > From what you say below, it sounds like you have the design but 
> > > > > have not built it yet??  If this is true, where did the 7.5 
> > > > > foot arcs come from??
> > > > >
> > > > > Gerry R.
> > > >
> > > > My SISG does about 28 inch arcs at 4800 SISG firing volts with a 
> > > > 165nF primary cap.  It would do about 42 inches if I let it loose 
> > > > with one MOT...  If DC can get 4800 Watts out of two MOTs, then 
> > > > the spark length directly doubles to 84 inches or 7 feet.  But he 
> > > > is using a bit larger primary cap too...  So 7.54 feet is about 
> > > > right.  I am a little concerned about getting 4800 Watts out of 
> > > > just two MOTs.  But DC might know tricks I have never dreamed of ;-))
> > > >
> > > > I have not thought much about the dual MOT SISG system...  But 
> > > > others are now thinking far faster than me on SISG things ;-)))))
> > > >
> > > > Cheers,
> > > >
> > > >         Terry