B.A.M!

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

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

[B]art [A]nderson's [M]agnifier -

It's New Year's Eve. Kids are gone and wife work's all night monitoring 
those heart patients. What's a guy to do! Set up a coil and run it of 
course. So went an hour or so of the night (ho hum, boredom sets in). I 
must be getting old.

Ok, so I pulled out one of the sections of my old 12.75" diameter coil. 
This is the old retired coil of which was cut down into 3 sections (I have 
2 of them, the 3rd was sent to Terry Fritz for 1:1 h/d testing). Always 
wanted to make a maggy out of one of these sections. So tonight, I thought 
I'd try a little maggy design.

Curious to those maggy guru's how this design looks:

Ok, the "extra" L3C3 (coil #3) will be an already built 4.5" coil:

I used Javatc for the whole shoot and match. Like this. Ran the extra coil 
with topload. Here's the specs:

Coil#3 Inputs:
2.26925 = Radius 1
2.26925 = Radius 2
13.835 = Height 1
34 = Height 2
900 = Turns
24 = Wire Awg
Toroid: minor=4.5, major=19.25, height=36.5, topload
Toroid Center Disc: inside=0, outside=11.25, height=37, topload

Coil#3 Outputs:
236.14 [kHz] = Secondary Resonant Frequency
19.561 [mH] = Les-Effective Series Inductance
23.223 [pF] = Ces-Effective Shunt Capacitance

-----------------------------------------------------
I then cleared coil#1 outputs and input coil#2 and coil#1 and setup a 
helical primary for a coupling coefficient between .5 and .6. Here's how 
the specs came out:

Coil#2 Inputs: (this is my old 12.75" diameter section I'll use for the 
driver).
6.375 = Radius 1
6.375 = Radius 2
0 = Height 1
15.125 = Height 2
350 = Turns
18 = Wire Awg

Coil#2 Outputs:
230.58 [kHz] = Secondary Resonant Frequency
16.648 [mH] = Les-Effective Series Inductance
28.617 [pF] = Ces-Effective Shunt Capacitance

Coil#1 Inputs: (this will be a new primary yet to be built).
7.375 = Radius 1
7.375 = Radius 2
0 = Height 1
5.308 = Height 2
7.07 = Turns
0.375 = Wire Diameter
0.021 = Primary Cap (uF)

Coil#1 Outputs:
230.58 [kHz] = Primary Resonant Frequency
1 [inch] = Primary to Secondary Clearance
22.787 [uH] = Ldc-Low Frequency Inductance
428.078 [uH] = Lm-Mutual Inductance
0.581 [k] = Coupling Coefficient
1.72 = Number of half cycles for energy transfer at K
2.89 [uS] = Time for total energy transfer (ideal quench time)
----------------------------------------------------------

That's it! Curious if anyone see's any glaring errors in design. I know 
many are still trying to get a grip on the Les and Ces numbers. Those are 
"at resonance" values for the coils, not DC measurement values. I did 
measure the DC inductance on coil#2 and coil#3 which of course match well 
the Javatc output, but it's only used as a cross check that the input 
parameters are exact or very near. The Ces and Les values I trust to define 
the resonant frequency's derived which account for coil#3's topload, 
groundplane, walls, ceilings. As well as coil#1 and coil#2 interaction.

It is interesting to watch how the resonant frequency changes with coil#2 
and coil#1 during the design. In other words, the proximity of a tightly 
coupled helical primary affects the coupling (obviously), but it also 
affects coil#2 Fres enough to cause significant attention (far more than we 
see with a loosely coupled classic Tesla coil).

Javatc for a maggy design? (I've never tried that before). It appears I 
will be able to use the old 12.75" coil for the driver. Looks like I have 
about everything I need except to throw the primary together.

I know this is a quick 20 minute design effort, but does anyone see any 
glaring errors in this design? Note, I didn't go back to any old emails and 
look up the latest maggy info. Just whatever was in my head at the time, so 
I know I may have missed something.

Thanks all,
Bart