making an inductor out of iron purely even the windings - Page 1
Forum section: electronics / beginners

author: robowaffe
author_rank: Regular Contributor
timestamp: July 27, 2023, 01:48:04 pm
content: So an iron core inductor gets x100 henry's.What happens if u use iron wire for it, does that do anything??

author: Ian.M
author_rank: Super Contributor
timestamp: July 27, 2023, 02:08:37 pm
content: Yes, if you made the current carrying windings out of iron wire, its higher resistivity (over 5.6 times greater than copper) and increased skin effect (by a factor of about 38) would drastically reduce its current capability and increase its output impedance, making it virtually unusable for any normal application.OTOH a wound iron wire core (or even cut and bent iron wire with generous overlap) with copper current carrying windings was the traditional method to build experimental electromagnets, inductors, transformers etc. in the second half of the 19'th century. The wire must have an insulating coating to block eddy currents, which was usually silk, varnish or black oxide, so if you want to DIY in the 21st century, enamelled soft iron florist wire is probably your best choice (if you *really* cant find a laminated core to suit).

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 27, 2023, 02:09:16 pm
content: A bundle of wire should work too for low frequencies.The core of toroidal transformers is made by rolling up a long strip of steel.But do note, the steel used for transformers has a high silicon content to lower the hysteresis of the magnetic field. You are probably also aware that it has to be laminated or rolled up in some way to reduce eddy currents.What is it you want to do exactly?Do you use iron (steel) wire as a current conductor, or do you want to use a bundle of steel wire to contain the magnetic field only?

author: robowaffe
author_rank: Regular Contributor
timestamp: July 27, 2023, 02:40:31 pm
content: So thanks for the information.I was just wondering using a magnetic metal for the iron windings, would it increase the henry's of the inductor? So u could do it with an air core and u still get 100x because the windings are actually iron!But probably not a good idea.

author: Terry Bites
author_rank: Super Contributor
timestamp: July 27, 2023, 10:25:21 pm
content: Read up on eddy currents and how they degrade transformer effciency. Its not just the magnetic permeability that matters, check out "Hysteresis loss" as well.You'll quickly understand what matters in core design. Real world transformers are not trivial to design.AC power transformers between you and the power station are > 97% efficient and above. Heat and noise are lost money, big money!

author: TimFox
author_rank: Super Contributor
timestamp: July 27, 2023, 10:47:50 pm
content: Also read up on what links flux into a core. The important flux is in the core (where you need iron or other permeable material) to get your inductance, more than with an air core.None of this information is classified and you can find many textbooks at public libraries.

author: Circlotron
author_rank: Super Contributor
timestamp: July 27, 2023, 10:56:54 pm
content: If a copper wire is carrying current the magnetic field “rotates” around the wire. What about an iron wire? Would the magnetism still rotate around the outside of the wire or would it now be inside the wire because of the lower reluctance path? And would this allow the current to be evenly distributed over the cross section of the iron wire, or would it cause skin effect even down to DC?

author: Ian.M
author_rank: Super Contributor
timestamp: July 27, 2023, 11:08:23 pm
content: Not down to DC but Wikipedia claims the skin effect 'depth' for iron @60 Hz is 220 um, so (unless Wikipedia's math is FUBARed) certainly not usable for a power transformer over a few VA.https://en.wikipedia.org/wiki/Skin_effect#Material_effect_on_skin_depth

author: TimFox
author_rank: Super Contributor
timestamp: July 27, 2023, 11:11:25 pm
content: Note that the AC skin depth is a function of both conductivity and magnetic permeability.