[TCML] Why don't big Tesla coils use helical primaries?
futuret at aol.com
Wed Aug 31 10:37:27 MDT 2011
You can use a helical primary if you'd like. You can use Bart Andersen's
excellent JavaTC program to try out various primary diameters to get a suitable
coupling value. By close winding the insulated wire, you can get a compact
primary coil. On one such coil I built, I had to make the primary about 10"
or more in diameter, for a 4" secondary to get the right coupling, or maybe
I was using a 6" dia. secondary, I can't remember but JavaTC will answer the
questions. I think I still had to raise the secondary some. I was getting at
least 40" sparks from that coil. The efficiency is the same for a flat primary
or helical primary. The efficiency is most affected by the type of wire on the
primary; wire gauge, solid or stranded, etc.
> so I was just wondering why no one uses helical coils with insulated wire
> like this: http://www.johndyer.com/MakerFaireJD06.jpgwhen building big
> static gap tesla coils.
> I have seen tons of small sgtc's with a primary like that, but it seems
> that with bigger sgtc's people always use copper tubing and carefully space
> them in a flat or conical spiral.
> I don't understand this. <snip
> thanks for the help!
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