Hello all...
I have a pair of iron core coils that i can possibly use.
Is it possible to determine their inductance using some sort of formula that takes into account the physical dimensions, wire gauge and number of turns?
I have a pair of iron core coils that i can possibly use.
Is it possible to determine their inductance using some sort of formula that takes into account the physical dimensions, wire gauge and number of turns?
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It depends on the type of iron-cored inductor: very broadly, they can be classified into two categories, open and closed.
An example of open type is a solenoid with a cylindrical core (or square section, it doesn't matter provided it is some kind of rod).
In this case, use the formula or calculator for air-core, and double the result (because ~half the length of lines of field are shorted by the core).
The result will be very approximate, like +/-30%, depending on various parameters.
Here is an example of online calculator:
Multi-Layer Coil Inductance Calculator
A closed type is a complete magnetic circuit, with an airgap added: for example, E and I laminations, with a calibrated sheet of insulating material in-between.
In this case, you can use the reluctance formula: L=n²µoA/e
n= number of turns, µo vacuum permeability=4π10E-7, A= core cross section and e= gap length, all in SI units.
This formula should be more accurate, like +/-10%, except if you have extreme gap lengths
Thanks for your time and help guys.
Now i see there is no really accurate way of determining L without proper measuring equipment... not serious though, I don't intend using them for anything approaching audiophile quality. just for "tinkering"
Now i see there is no really accurate way of determining L without proper measuring equipment... not serious though, I don't intend using them for anything approaching audiophile quality. just for "tinkering"
multimeters with capacitance and inductance measurement are common these days and relatively cheap
DMM Digital Multimeter with LC Inductance Capacitance and Frequency
DMM Digital Multimeter with LC Inductance Capacitance and Frequency
Thanks Adison...guess I'm a little behind the times! I do have to wonder about availability and price down here at the tip of Africa. Guess a little shopping around is in my future.
Cheers!
Cheers!
I find using a sig gen and scope I can measure inductance ok.
Put a resistor and capacitor in series with the coil.
Apply a sine wave through sig ne and see at what frequency there is minimum signal across the LC.
You can then work out F from:
F=1/ (2 pi SQROOT(LC))
Put a resistor and capacitor in series with the coil.
Apply a sine wave through sig ne and see at what frequency there is minimum signal across the LC.
You can then work out F from:
F=1/ (2 pi SQROOT(LC))
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