Experimenting with Magnetic Components - DIY Inductance Meter

RE: Experimenting with Magnetic Components - DIY Inductance Meter

Jan Cumps — Thu, 31 Mar 2022 11:04:42 GMT

Another option if you don't have an LCR or L meter, from EEVBlog.
Use the capacty mode of your DMM:

[View:https://www.youtube.com/watch?v=UrS5ezesA9s:640:360]

RE: Experimenting with Magnetic Components - DIY Inductance Meter

Jan Cumps — Fri, 19 Nov 2021 17:27:26 GMT

The challenge is finished, time to recycle the material

[View:/resized-image/__size/620x471/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4c8f9dae-0368-49d9-ab5c-a35ad35a59ce/contentimage_5F00_217705.png:620:471]

If you are interested to review the inductor kit, and you want to eat the mail charge, I can send it to you.

Without the box, in a padded envelope, the shipping costs shouldn't be too high. Open for swap too.

Let me know if interested.

RE: Experimenting with Magnetic Components - DIY Inductance Meter

genebren — Mon, 08 Nov 2021 14:51:53 GMT

Excellent blog/experiments. The attached video was interesting and informative, thanks for sharing!

RE: Experimenting with Magnetic Components - DIY Inductance Meter

jc2048 — Mon, 08 Nov 2021 10:07:38 GMT

The core you've chosen is intended for EMC use, so it's designed to be lossy from a few tens of megahertz upwards.

This is the consequence for the permeability

[View:/resized-image/__size/356x356/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4c8f9dae-0368-49d9-ab5c-a35ad35a59ce/contentimage_5F00_217123.png:356:356]

it's already starting to decline around 1MHz, and by 2.5 MHz it's down from the LF value of 850 to about 750, so I think that's why you see the inductance value changing. I imagine the core will also be beginning to absorb rf, which might be why you have the oscillator problem (if you've set the loop gain low for a good waveshape, the additional absorbtion will be dragging it down to the point where the oscillator would be struggling). Could be more to it than that, but it's a starting point for thinking about what is going on.

RE: Experimenting with Magnetic Components - DIY Inductance Meter

Jan Cumps — Sun, 07 Nov 2021 19:06:08 GMT

2 updates:

you don't need a spreadsheet or calculator. The original article has a conversion table (check it for readable size).:

[View:/resized-image/__size/278x269/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4c8f9dae-0368-49d9-ab5c-a35ad35a59ce/contentimage_5F00_217119.png:278:269]

I suspect that my hand-wound gives a bad reading due to stray capacity. It's mounted on a PCB.

All other tests were done with the inductor directly plugged into the test device.

For sanity, I just tested #3 of the kit, in the same µH range as the one I made (47 µH), and that one measured around 50 µH - within expectations.

[View:/resized-image/__size/400x761/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-4c8f9dae-0368-49d9-ab5c-a35ad35a59ce/contentimage_5F00_217120.png:400:761]

I could calculate that stray capacity if I wanted, because I know its inductance (measured it), and when I remove C1 from the test device, the circuit oscillates with this setup plugged in....