# How to measure inductence at a aparticular frequency?

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#### UroBoros

howto measrue al of toroid

I have a self wound toroid. I measure the inductance using a inductance meter .it shows 330uH. The meter manual says it measure inductance at 1khz.

I am going to use this torroid in 52Khz.

How to measure the inductance of this coil in 52Khz?

Thanks

measuring toriod inductance

An ideal inductor should have moretheless the same inductance independently of frequency ..
That’s the theory ..

If you want to measure inductance at particular frequency you have to build a small oscillator where an inductance is the part of the LC tank ..
The basic mathematic formula of the LC tank allows you by adjusting variable capacitance to operate at the selected frequency and that also allows you to calculate the value of L ..
Here are examples of simple (2 x PNP) oscillators:

rgds,
IanP

http://en.wikipedia.org/wiki/LC_circuit

### UroBoros

Points: 2
how to measure induction of a coil

Thanks for the replay.

I am doing a LM2576 based simple switcher. For that I need 330uH inductor.(52khz)
I have located a calculator which accepts my datasheet values for AL and gives output which Tally with practical coil measurements in my inductance meter.
My T-21.0 core (Outer dia 21mm, inner dia 13mm height 12.5mm) Al value is 3530.

On winding 9 turns it gives 340uH in meter. I need 330uH Only.

Now another issue is saturation flux density. As per my toroid data sheet it is 480.
How to calculate the flux density when 2Amps flows through winding?

Thanks

how to measure flux density of toroidal

inductance vary as current goes up.....with ferrite it starts to slope up as current rises.

is that ferrite good for 50khz....diferent ferrites have different hyteresis and eddy losses at diffrent frequencys

### UroBoros

Points: 2
how to measure frequency

eem2am said:
is that ferrite good for 50khz....diferent ferrites have different hyteresis and eddy losses at diffrent frequencys

The datasheet is not having any details about frequency range. As these cores are used in SMPS power supplies, it should work. It mentions about losses at 100khz etc.

The saturation is depending on the area of cross section of core ?

Thanks

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