The local electronics surplus store sells a few standard ferrite toroid
cores made of either #43, #61, or #75 material. I looked at the
following randomly-googled chart for remarks about each of those
materials: 193.6.189.120/letoltes/HG0MAT/toroid_datasheet.pdf

I want to buy a few toroid cores for "general purpose" use. Forgive my
ignorance; I understand that the correct material must be chosen for a
given purpose, but I'm still learning the math. Most of my use will be
for power applications and I would like to make my designs as efficient
as possible. Example uses: hand wound toroid inductor for various high
current SMPS from 30kHz to 3MHz, small power inverter at 60Hz,
experimenting with multiple windings, etc. Looking to wind them in an
inductance range of 1-100uH or possibly up to 500uH.

A few questions:

1. What core material would be good for my purpose(s)? I will probably
get a couple of each. I understand this may be a stupid question, but if
I had to pick only one or two materials, what would be a good core
material for my "general purpose" use above?

2. What is volume resistivity and what role does it play for things like
a toroid inductor in a ~600kHz boost converter?

3. I have read somewhere (quite possibly an unreliable source) that
lower permeability somehow correlates to higher current capability. Why
would someone state that?
--=20
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