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[mcorrade]

Not sure where to post this but;;;;;;

I need some basic and "more than basic" "how too" on making coils. What the best material, best gauge, best core and best winding technique....

thanks,
-mike

[EMdevices]

Hi Mike,Ã,  a coil is such a simple device, but if we realy think about it, your questions are realy relevant and there can be said quite a bit about a simple coil of wire.

Here's some of my thoughts.

1)Ã,  A coils usefullness in a circuit is due to it's inductance.Ã,  You need to know what inductance value you are shooting for.

2)Ã,  What frequency will you be using it at?Ã, Ã,  For higher frequencies you need to implement a bit more special winding to avoid self resonance, hence a loss of the usefull inductance you need.

3)Ã,  If the inductance requirement is realy high,Ã,  you can get that by adding core material.Ã, Ã,  But then again, the core material needs to be chosen based on the frequency, (make sure the loses are not that high at the operating frequency)

4)Ã,  Having said all that, your circuit or aplication should make it clear to you what kind of currents will flow thorugh your coil.Ã,  Then you would have to choose the right size wire to handle the heat.Ã,  A lot can be said about applications on the cutting edge of heat disipation, what coating to have , number of layers, etc..

5)Ã,  Now, if you do want to operate the coil at it's self resonant frequency, like the Tesla secondary coils,Ã,  then you want to use only one layer of coil and I guess you choose the wire size you have laying around the houseÃ,  :)Ã,  Ã,  that's what I do.Ã,  But in reality, the thicker the wire the less the resistance and the higher the Q, hence the higher the voltage you can achive (I think)

Anyway,Ã,  the main point to keep in mind is that Inductance and your circuit application will tell you what you need.

EM

[mcorrade]

I really just want to make a secondary coil to produce electricity from a spinning magnet rotor. I would like to know very simple things like which end of the wire coming from the coil is negative or positive? Should I use a solid or air core for this type of application?

thanks again......