On 28/12/2012 07:13, Sean Breheny wrote:
> Hi David,
>=20
> Here are a few of the most common applications of inductors (you
> probably know this but I want to refer back to this so I will list
> them):

Sean,

Thanks for your excellent reply.  It has taken me a few days to digest
and there are questions in line below, but this helps immensely.  I can
now go and read datasheets for the different types of inductor with a
slightly better understanding.

I will have to spend some time reading the ARRL Handbook for inductors
again to understand better how Q relates to the frequency (I find it a
very well explained book, even though I'm not into ham radio).

> For RF tuned circuits/impedance matching/filters, you want high-Q
> inductors (i.e., low loss)

What region of values would be considered "high-Q" for these RF circuits?

> RF circuits like these will not usually employ molded inductors
> because they are not the lowest loss type of construction. Toroidal
> inductors are common. For VHF and up, SMD inductors are common - often
> with visible turns of wire as you mentioned.

This explains why a number of the amateur radio circuits (for HF bands)
I have been studying use custom wound toroidal inductors.  Previously I
had assumed this was only for power levels involved.

I could wind my own with toroids, but for prototyping I'd much rather
use something with a known inductance value, hence the original question
about what type to use.

> Switching power supply energy storage inductors generally must be
> large enough to avoid saturation and to minimize core losses.

I assume we avoid saturation as the inductance of the device decreases.
 As I understand when saturation occurs the inductor acts less like an
ideal inductor and more like a short (or small DC resistance).

Thanks once again for taking the time with your reply, it was incredibly
useful.

David
--=20
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