more inductor questions.

[nuttinbutSQ]

Ok this is just a general Q on inductors. What is the differance between standard wire wound air core inductors and foil air core inductors? (I understand one is foil and one is wire) Which one is better and why? Also I see some of you making your own inductors, they do get expensive buying them. Can someone point me to a website or a book to learn how to make my own. When you make your own, how do you test them so you know you have the correct mH and resistance?

Thanks,

D.

[Magura]

The difference between foil and wire inductors is supposed to be the skin effect....the difference in real life is close enough to zero to be called zero (im gonna get a beating for saying this, but ive been testing both...no difference detectable).

As for winding your own inductors, thats no big deal. The biggest problem is to get the wire, and especially to get the wire for a reasonable price. Besides that its as i wrote before on another thread, just a matter of making the inductors with as low resistance as possible.

Here is a link that explains DIY inductors well.

http://www.colomar.com/Shavano/inductor_info.html

Magura

[Sch3mat1c]

Heh, besides skin effect being negligible, it just causes DCR to rise along with ACR (reactance), basically lowering the Q... if you wanted high Q for a x-o choke, you wouldn't be using an air core...

Seems to me, foil would have more capacitance as well, but again a negligible effect at 20kHz.

Tim