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# Re: Calculating inductance...

```On Fri, 17 May 1996 21:58:36 -0600, Tesla List
<tesla-at-poodle.pupman-dot-com>, you wrote:

>>From chip-at-grendel.objinc-dot-comFri May 17 21:43:36 1996
>Date: Fri, 17 May 1996 16:16:22 +0700
>From: Chip Atkinson <chip-at-grendel.objinc-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Calculating inductance...
>
>Just a couple questions:
>
>Z is AC current? (as in V = IR)
>What is a sense resistor?  Just a resistor of a known value?
>Z=2piFL, F is Frequency?
>
>I'll try it this weekend, and if I don't get a reply, I'll try it with the
>assumptions above.  However, my volt meter is suspect, so I'll try
>to get it to read some roughly known values accurately.
>
Chip,
Z is AC resistance. as in V= I Z

F is frequency

The sense resistor is just a small known value resistor in
series with the "unit under test" the inductor in your case. When I
say small, I mean a resistance that is less than about 1/10 of the
impedance (Z) of your inductor. If you use a "large" value then the
equation becomes V = I * ( Z + R) which is more difficult to solve.
With R "small" you can just drop it out of the equation. (assuming
that you don't mind an inaccuracy. 1/10 of Z = 10%, 1/100 of Z = 1%.

Regards,

jim
```