an inductor is a reactive device that opposes changes in current. it stores energy in the magnetic field created by current flowing through the windings. For a given input voltage, the faster the current changes (the higher teh frequency) the higher the impedance becomes.
An ideal inductor has impedance: Xl = 2*pi*f*L
A real inductor will have impedance:
X = sqrt(Rdc^2+(2*pi*f*L)^2)
The easiest way to measure inductance is to neglect Rdc, hook up a resistor of 8-10 ohms in series with the inductor and feed the pair with a signal from a signal generator (could be a sound card). MEasure the voltage across the inductor and the voltage across the resistor. If the voltage across the resistor is greater, you raise the frequency and vice versa. When they are equal, you know that the resistance of your test resistor is equal to the reactance of your inductor.
R=2*pi*f*L - so L = R/(2*pi*f)
You can do the same with the more complicated formula (you would need 2 frequencies since there are 2 unknowns, or you can measure Rdc first).
If you don't want to do this, you can get a program called speaker workshop which will allow you to measure capacitors, inductors and speaker T/S parameters after building and calibrating a jig that is basically a more complicated version of what I describe above.
incidentally, you can measure capacitors with the same method above, but C = 1/ (2*pi*f*R) when the voltage across resistor and capacitor are the same.
An ideal inductor has impedance: Xl = 2*pi*f*L
A real inductor will have impedance:
X = sqrt(Rdc^2+(2*pi*f*L)^2)
The easiest way to measure inductance is to neglect Rdc, hook up a resistor of 8-10 ohms in series with the inductor and feed the pair with a signal from a signal generator (could be a sound card). MEasure the voltage across the inductor and the voltage across the resistor. If the voltage across the resistor is greater, you raise the frequency and vice versa. When they are equal, you know that the resistance of your test resistor is equal to the reactance of your inductor.
R=2*pi*f*L - so L = R/(2*pi*f)
You can do the same with the more complicated formula (you would need 2 frequencies since there are 2 unknowns, or you can measure Rdc first).
If you don't want to do this, you can get a program called speaker workshop which will allow you to measure capacitors, inductors and speaker T/S parameters after building and calibrating a jig that is basically a more complicated version of what I describe above.
incidentally, you can measure capacitors with the same method above, but C = 1/ (2*pi*f*R) when the voltage across resistor and capacitor are the same.
You can use ARTA (Limp) to do that.
I just use line out and a 10ohm resistor. And line in. Nothing fancy just on-board sound.
You can sample the LCR values at any frequency desired.
I use Pink noise with the largest FFT size available.
Works great and seems to be accurate enough with my setup.
Values from high quality componens seems to fall within spec.
Resistance after the resistor can be a problem and something to think about if the component measured has very low ESR.
http://www.fesb.hr/~mateljan/arta/
*edit* Free version works great.
I just use line out and a 10ohm resistor. And line in. Nothing fancy just on-board sound.
You can sample the LCR values at any frequency desired.
I use Pink noise with the largest FFT size available.
Works great and seems to be accurate enough with my setup.
Values from high quality componens seems to fall within spec.
Resistance after the resistor can be a problem and something to think about if the component measured has very low ESR.
http://www.fesb.hr/~mateljan/arta/
*edit* Free version works great.
Ron and David have it covered.
I use speaker workshop, but I admit that the learning curve can be steep. It's really not that bad though, you only need a couple of resistors and a few cables to get started.
Claudio has an excellent site describing the setup process: http://www.claudionegro.com/
-David
I use speaker workshop, but I admit that the learning curve can be steep. It's really not that bad though, you only need a couple of resistors and a few cables to get started.
Claudio has an excellent site describing the setup process: http://www.claudionegro.com/
-David
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