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I would also like to state that usually you can measure the inductance with a LCR meter instrument. That instrument send a sinus through the coil and looks at the result - and then calculates the value.
With a LCR meter you can also measure the series resistor that is also a part of the coil.
Sometimes when working with Air coils with a little internal resisistance, you use a Q-meter instead to measure inductance and series resistance.
If you know a electrical engineer, he will probably have acces to a LCR meter.
Physical inductors are the least ideal of the various passive elements. They have parasitic resistance and capacitance and ones with metal cores are affected by the current.
Most measurements of inductance by low cost meters are at a low enough frequency that the parasitic capacitance does not affect the measurement. The signal levels are low enough that amplitude effects are absent.
To be more accurate, you should use a measuring scheme that operates at the conditions (frequency and current AC and DC) that you will use the part.
There are devices called magnetic amplifiers that take advantage of the nonlinear inductance with DC current to do "amplifying" functions. Actually the gain goes from 0 to 1 which is good enough in power applications. The first widespread use of this device was in German U-Boats in 1940 or so. After the prices of 4 layer semiconductors (SCR triac etc.) got low enough the magnetic amplifiers were never used again. They withstand atomic radiation very well and could be used in atomic power plants and space satellites. I do not know if they are in reality.
there is a simple way i used to do to give first order estimate of inductance value, but you must know a range where the inductance value falls in. simply connect a known cap shunt with the inductance, connect a suitable resitance value series with the LC tank, apply a signal generator to the resitance terminal and change frequency in the range you expect the LC tank to resonate, probe the AC voltage accross the tank with a simple AC meter, just when the meter peaks record the frequency value and susbtitute with the known Cap value in the well-known resonance equation to get the inductance.
This method has the following limitations:
1- A range for L should be known to tune the signal generator.
2- used cap should be much greater than the stray capacitance of the inductor as flatulent mentioned.
3-used resistance should be close in value to the parallel loss resistance of the tank.
4- and of course the AC meter should be able to detect the AC signal, which is advised to be small, few 100s KHz.
regards,
the best way to measure any passive element (resistance, inductance and capacitance), ideal element or practical element, which have mixed of passive elements is by step response. You need function generator with square wave and oscilloscope. In that way you can find all the components the main and the parasitic as well. In one measure
If you need more detail about the measerment PM me.
I'm working in the same project.
I need to measure an inductance between 1MOhm to 10MOhm, passing through them a 1 KHz sine current (a specific value of current).
Which is the best method to do that?
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