Re: Help calculating L to match C

[Pyrotrons-at-xxxxxxx (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Hi Seth.

There are many different ways to design a Tesla coil, keeping in mind that 
all components are based on all the other components!

If you already have a transformer, here is a really good way to design a coil 
around it.

* calculate tank capacitance based on transformer winding impedance
* choose a secondary coil based on input power level from xfmr
* choose a good looking toroid for that secondary coil 
* calculate Fr of secondary circuit
* calculate primary inductance needed for tank Fr to equal sec. Fr
* given 1" clearance from primary coil to sec coil, calculate # primary turns 
to get the needed inductance.
* any 'ol spark gap

There really is no perfect toroid capacitance to use, my suggestion is to 
just pick a size. Make it look good sitting up top. It will work just 
fine....but you'll probably get longer sparks from a larger topload.

Several people have used basically the same setup for 15kV 60mA transformers, 
including myself. 

* 4.5" secondary 21" long or so.
* 15 turn 1/4" copper tubing primary coil, 1" clearance from sec, 1/4" turn 
to turn spacing
* .02uF tank capacitor (I used a resonant .0106uF one....it was cool)
* Cylinder spark gap, good # of electrodes...8 or so. .35" spacing at the 
most, although I've pushed mine past .4" just fine (wow). Airflow is 
definately needed.
* Many people have used 4" dryer duct toroids, 20" or so in overall diameter. 
I've used up to 8" duct.....got longer, hotter sparks. 

I agree with Terry....do the calculations yourself with a calculator to get 
familiar with what's going on. When I started, I went back-and-forth from 
paper to program, paper to program......verifying that my hand calculations 
were right.

Maybe this is a typo but I noticed something in your post...

>15/60 NST
>50Hz supply
>LTR Cap=0.28uF MMC (2.2xresonantC)
>Xc=113636 Ohms

You wrote 0.28 (zero point two eight) uF. You're looking for .028 (point zero 
two eight)uF. Probably a typo but making sure.

Well that should give you a good idea of what a 15/60 will power. I got 3.5 
foot arcs with my system, you'll probably get more ; ) Coiler Gary Lau 
reports getting 52" from a 15/60......!!!

Take care,

Justin Hays
KC5PNP
Email: pyrotrons-at-aol-dot-com
Webpage: www.hvguy-dot-com