Re: OLTC maggy

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

Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 14:55 06/04/03 -0600, you wrote:

>However,I would strongly recomend you to go for mode
>(2,3,4) and transfer in 1.5 cycles with k=0.57.
>Not becouse k=0.67 looks scarrry but there is
>another,special reason I opt for that.
>Since you are reading Antonio's paper think why.
>If you don't figure it out, Antonio or I will tell
>you.
I entered Antonio's design equations into a spreadsheet and ran some 
numbers for a design reusing the resonator and tank cap from my existing 
OLTC. For mode (1,2,3) the secondary coil turned out almost the same 
inductance and top capacitance as the resonator. I assume the top voltage 
of the secondary coil would reach almost as high as the resonator, and 
there would be real trouble achieving tight coupling to a coil running at 
such high voltage without (a) flashover or (b) adding plastic insulation 
which would probably add more extra capacitance than the system could tolerate.

http://www.scopeboy-dot-com/tesla/magcalc123.jpg (1,2,3)

I also tried with (2,3,4) and the secondary inductance is much less and 
capacitance much more. The secondary will be physically smaller, top 
voltage will be lower, hence easier to get tight coupling (besides the 
coupling required is less)

http://www.scopeboy-dot-com/tesla/magcalc234.jpg (2,3,4)

Am I on the right track?

I also investigated the kickback issue a little more. Here are some screen 
grabs of a PSpice simulation that shows the problem.

http://www.scopeboy-dot-com/tesla/t3model.jpg
http://www.scopeboy-dot-com/tesla/oltcsim1.jpg

And here is a scope screenshot of the actual tank cap voltage

http://www.scopeboy-dot-com/tesla/oltctrace.jpg

Sadly, it looks nothing like the simulated trace. I'm going to simulate the 
maggie design in PSpice anyway to see what happens. If it looks good I 
think I will probably convert my mini OLTC to a maggie. This will be a good 
experiment. Same resonator, same IGBTs, same tank cap, same power input, 
we'll see if the maggie makes bigger sparks, or even the same length sparks 
more efficiently.

If it does, I'll double the tank capacitance, redesign the primary, bolt on 
two extra IGBTs, and increase the BPS to 1600. That will get me into the 
800 watt range that Boris challenged me to achieve ;D

Steve C.