What wire do I use for LC filter Inductor?

Hi all!

What wire do I use for the inductor in an LC filter? Is it OK if I don't use bare copper wire, or enameled copper wire, but instead use insulated copper wire?

Thanks in advance!

You need to consider the: voltages in the circuit, current flowing, the physical size needed, the inductor value required.

Enamelled wire has been used for ever to make inductors.

For small inductor values 30 AWG Kynar wire wrap will also work.

You may need a ferrite core also.

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I am using it for a bass filter on a speaker. The amplifier is powered from 12V and has 40W out.

I am trying to copy the inductor in the video the @jremington posted here: Low Pass RC Filter - #2 by jremington

It doesn't say what inductor value it is, just 100 wraps of 0.5mm enameled copper wire.

I do have some 20awg solid copper wire but it is insulated. Is this ok to use?

I also have 500ft of 34awg enameled copper wire, but I would assume that is too small for this application.

.5mm is ≈ 24AWG.
With plastic insulation, the number of turns would need to increase accordingly.

So would 100 wraps of 20awg that is coated be somewhat equivalent to 100 wraps of 24awg that is not coated? I'm thinking the larger size might counteract the plastic insulation.

True, but is really hard to find because nylon coated wire is used now because nylon is flexible where enamel coating becomes brittle. Also be sure to clean the insulation off the ends so you can solder them.

So it's ok to use insulated wire instead?

No. The inductance is based on the number of TURNS of wire. You want the thinnest insulation possible to get the turns count without winding a monster coil. The insulation only has to protect the adjacent turns, so that voltage is really really small.

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Magnet wire is best for inductors.

If this is for an audio crossover...

  1. You CANNOT use bare wire.
  2. Enamel is the best
  3. insulated copper wire is acceptable

You want the insulation to be as think as you can. Thicker insulation will reduce the overall inductance. However if space is not at a premium then insulated wire will work fine.

It would be best if you could find an online inductance calculator that considered the insulation thickness.

No, space isn't a problem at all. I just tried looking up a calculator, and didn't get anywhere. I tried several searches and looked through about 20. None include wire insulation thickness.

Do you know any formula :thinking: for that?

ECW is not covered in "enamel" - not for decades in fact. Its often polyurethane coated, which is tough and flexible and can be burnt off in a solder pot to allow easy soldering to the tails.
ECW is also known as "magnet wire". There are various types of insulation available for magnet wire, reflecting different insulation and thermal requirements. Manufacturers' datasheets are where you find these details out.

Note that burning off polyurethane releases some cyanide fumes so if you do this, good ventilation is needed.

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Why did you start a new topic for this question when you had already asked it and got answers in Low Pass RC Filter - #11 by kgray9

I just got a answer not long ago. It was a different question, under the same topic as another question, so I made a new topic instead because that makes more sense.

How does asking the same question in 2 places makes sense ?

This Topic has been locked as it is the identical or too similar your other post.
Please use the original post and do not duplicate.