11 Turns is a Small Sample for these Calculations.
BUT If 11 Turns = 0.5 mH
To Find AL Value
1000/ 11 turns =90.9090909
90.9090909 * 90.9090909 (Squared) = 8264.45
* L in mh = AL Value
8264.45 *.5 = 4132
AL Value = 4132
To Find the Turns required to get 26 mH, knowing this AL Value in mH.
26 / 4132 = .0062923
Square Root of .0062925 =.079324
.079324 * 26 = 79.32 Turns <THIS IS WRONG>
SHOULD BE: .079324 * 1000 = 79.324
So 79.32 Turns on that Same Torroid will give you a 26 mH Choke.
But A Better Torroid would be a 77 or 78 Material.
And it should be Fairly large to use Large Wire as needed.
Very good post.
I would like to add what little I know about toroids, or think I know.
1. The color of the toroid indicates the material it is made from, thus permeability, etc. Basically toroids are poorly marked. The colors are not standardized between manufacturers. They usually have no markings at all. If you buy a toroid with no manufacturers markings on the package, plan to spend some time finding out what it is for.
2. The size of the toroid ring determines the number of turns, and the size of wire that can be wound on them. It also determines the saturability of the toroid. Again, as I understand it, the a toroid is a field device. The field builds up from the outer surface of the coil to the inner. A point is reached where there is no capacity in the toroid for a larger field. As I understand it, this is the saturation point. The larger the cross sectional area of the toroid, the more field it can accept.
3. When winding a core, try to keep the number of turns to a reasonable number. You don't want a tiny toroid with 47 layers of wire wrapped on it. As I understand it, moving the windings away from the toroid, as multiple layers would, can affect the value of inductor.
4. Use double sided tape between the toroid and first winding, and between each layer. It makes it easier, but not easy, to keep the turns in place.