Timeline for What types of materials increase the inductance of a coil when inserted inside it?
Current License: CC BY-SA 4.0
10 events
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| May 23, 2019 at 11:14 | comment | added | Zeiss Ikon | Hmm. I have a form with a fast-twist screw insert that's size just a little bigger than common ferrite rod. Looks like I might have to build one and test it after all. Time to order some ferrite rods. | |
| May 22, 2019 at 20:22 | comment | added | Mike Waters | My tests used a couple of 4" diameter x 6" long coils, but the piece of ferrite rod was much smaller in both directions. What is needed are some better tests, using a smaller and shorter coil in a more suitable ratio, as I think that would give a significantly larger increase in inductance that what I observed (IIRC, roughly from 20 µH to 27 µH). Such a real-world, practical test would also make a great answer here. | |
| May 22, 2019 at 14:05 | history | edited | Mike Waters | CC BY-SA 4.0 |
Added quote from w8ji.com
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| May 22, 2019 at 13:59 | history | edited | Mike Waters | CC BY-SA 4.0 |
Added link to w8ji.com
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| May 22, 2019 at 13:57 | comment | added | Zeiss Ikon | This makes complete sense. I (the author of the question in the link) had been thinking steel would increase inductance, because it does at frequencies where I have experience (AC line power, 60 Hz in the USA). After reading the "steel wool balun" article, I now understand why this changes at higher frequencies -- same reason we don't see steel core RF transformers. | |
| May 22, 2019 at 11:54 | comment | added | tomnexus | Well done for taking actual measurements. I'm still itching after seeing the steel wool near the instruments. I'm sure there's a frequency at which a steel bolt does increase the inductance of a coil, but it's probably below 100 Hz. | |
| May 22, 2019 at 5:06 | comment | added | user10489 | Steel probably increases the inductance, but any increase is hugely overshadowed by losses caused by eddy currents in the solid metal piece. The point of powdered ferrite/iron is to increase the inductance while not presenting a large enough contiguous conductive piece of metal that can allow eddy currents. | |
| May 21, 2019 at 22:44 | history | edited | Mike Waters | CC BY-SA 4.0 |
added 69 characters in body
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| May 21, 2019 at 22:39 | comment | added | Mike Waters | "Mild steel" is what common, ordinary Grade 5 hex-head screws, bars, and bolts are made of. What your local hardware store and steel warehouse offers. Type 1018 or 1020, as my freshman high school machine shop teacher told us boys. | |
| May 21, 2019 at 22:20 | history | answered | Mike Waters | CC BY-SA 4.0 |