Ballast Form and Function

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gregory Morris <gbmorris@xxxxxxxxx>

Hey folks,

Sorry if this is trivial, I generally like to search the archives 
before asking questions like this, but it seems somewhat specific.

First of all, what I think I know: ballast is for current limiting, 
it is basically a length of wire wrapped up in a volume-efficient 
bundle--essentially a big resistor--and sometimes is wrapped around 
an iron core to get the added effect of the impedance of a  good inductor.

And what I'd like to know: what range of resistance is good for a TC? 
Is the iron core necessary or just beneficial? Specifically I got a 
little heating element from dismantling a broken 1500W kettle. It is 
about 2" - 3" in diameter and a quick calculation tells me it has a 
resistance of about 10ohms. Is this applicable to the new 9/30 
powered coil I am building, or should I just scrap it with the rest 
of the kettle? If so, do you have any advice or links for when I make 
my own ballast?

Thanks,
Greg