Variable Mutual Inductance Primary Tuning (VMIPT Sorry :o)))

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi All,

I did a little experiment tonight:

http://hot-streamer-dot-com/temp/P7260002.jpg

I took two loops of 3/8 inch copper tubing 11.5 inches in diameter shunted
with 0.10uF caps.  I placed them across a meter stick about a yard long and
measured some Fo frequencies...

Space (in)	Fo (kHz) 	L(uH) (0.2uF)
0.5		480		0.55
1		481		0.55
2		526		0.46
3		551		0.42
4		565		0.40

These measurements probably have a generally high error ;-))

So I get a pretty good variation in Fo frequency :-))  Prolly good enough
for the Off-Line coil.  Not as great as it could have been, but pretty good
anyway :-))  So I am thinking of dual primary tuning now...

Jim and Antonio think the range is only 1/2 to 1, so I'll trust them :-))
But even that is really good!!!  If L varies by 50%, Fo will vary by
SQRT(0.5) = 0.707 to 1.00.  Many thanks for the insight here guys :-))


BTW - Many thanks(!!) to Sean Taylor for the link to:

Richardson Electronics

http://www.rell-dot-com

They have the "magic"  CD - caps (or can eventually get them) for only
$4.76 each!!!!  That suddenly takes $150 off the price of the OLTC!!!!!

So not only is the OLTC the most efficient and lightest Tesla coil capable
of 5+ foot arcs, but now I am thinking of it also being the cheapest :-))))

Of course, it only exists as paper and models in RAM memory chips at the
moment...  But working hard on making it "real"...  I think the project
will enter the "waiting for parts" stage now ;-))  It has now gone onto #1
priority and unlimited budget status :-))

Cheers,

	Terry