Thomas Schmit wrote:
Hi Everyone, I was just wondering how the 1000 turn rule of thumb was developed. Is this a purely "practical" consideration - i.e. larger number of turns results in corona discharge and insulation failure at the top of the secondary or is there a theoretical reason behind it? Or something else entirely?
I think it's just how things come out. If you were to wind a BIG coil with really fine wire (and get thousands and thousands of turns), you'd have a lot of inductance, and you'd have trouble getting resonance with a practical sized top load (e.g. the fRes would be really low) Not only that, but winding a big thing with small fragile wire would be hard.
Going the other way, using relatively few turns of big wire on a small form runs the inductance to low.
It also has to do with the typical form length and the ease of close spaced turns.
Some folks have experimented with secondaries wound with a spacer, and got good results. halving the number of turns cuts the inductance by a factor of 4, so you need a substantially larger topload to keep the resonant frequency the same.
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