# Inductance of 820 ohm 10w wirewound - Page 2

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Re: Inductance of 820 ohm 10w wirewound

"Phil Allison"

I'll even give you the formula:

Xc =  1 / ( 2 . pi . F .C )

....  Phil

Re: Inductance of 820 ohm 10w wirewound

Thanks very much.

Re: Inductance of 820 ohm 10w wirewound

Thanks, apart from the completely unneceassry last word. I am loath to
killfile you because you often post good sense. Could you try not to be so
childish and nasty with it?

Re: Inductance of 820 ohm 10w wirewound

**I did not suggest that you try to measure inductance. I said you should
measure INDUCTIVE REACTANCE. BIG difference.

All you need to do is:

Measure the resistance.
Measure the total reactance at (say) 100kHz).
Subtract the resistance and you are left with inductive reactance.
With the inductive reactance figure, you will be able to calculate the
inductance.

--
Trevor Wilson
www.rageaudio.com.au

Re: Inductance of 820 ohm 10w wirewound

"Trevor Wilson"

** That second job is not possible.

The Z value will be exactly the same as the resistance.

Try 100MHz instead and then see how a few pF of strays ruins the outcome.

....  Phil

Re: Inductance of 820 ohm 10w wirewound

*if* it's a straight coil of wire with an air core, then Wheelers formula
gives a reasonable result for inductance.

L (uH) = (r*r + n*n) / (9r + 10l)

Dimensions all in inches.
r = coil radius
n = no of turns
l = coil cylinder length