[RyanGuyardo (OP)]

I need to make a small size inductor which is 100mH for inductance.

It has to be:
- Small in size
- Light
- Not too many number of coils
- Easy to find material (better be something easily found at home)
- It can be any core


Any idea of doing this?
I've been trying this lots of time but its inductance is way too low (less than 5mH).
Please help out

[Soul Surfer]

what range of frequencies are you planning to use your inductor for? and is the Q factor important?

[lyner]

Why not buy one from a catalog?
The only problem would be if you demand low self capacity. As you need it to be small, then I think this would not be a problem.
A component 'off the shelf' would almost certainly be smaller than one you could wind yourself. The wire used in many components is smaller than you can actually see!

[techmind]

You also need to specify what normal maximum (and maybe pulse) current you want the inductor to handle (this is related to power-dissipation).
If the power was very low you could use very fine wire and make a very compact inductor. If it needs to carry more current then you'll need thicker wire and everything will get bigger.

For 100uH you would normally use some kind of ferrite core, but the particular material chosen depends on the highest frequency that the inductor is required to work at.

The core probably needs to be made of ferrite - the only "home source" for that is a ferrite-rod internal antenna from an unwanted mediumwave or longwave radio. You can also buy ferrite rods from Maplin or other electronics hobby stores for a couple of pounds/dollars apiece.

For the smallest, highest power devices you need to have a lap-wound (tidy layer wound) coils which conduct the heat well (as opposed to random pile-wound). If this is for a commercial application (and you have appropriate budget) then there are a few specialist companies in the UK which can design inductors to order.

[RD]

What about using a mains (step down) transformer as a large inductor ? (100mH is quite large)

The primary windings (mains side) will have greater inductance than the secondary (appliance side).

Don't use mains electricity unless you know what you're doing.
 

[lyner]

Rather than letting us speculate, why not tell us the actual application?