Re: [EE] Small electromagnet cores?

I needed some small electromagnets a number of years ago and realised I
could tear down some of the PCB mount signal relays I'd pulled from scrap
boards.

Clint. M0UAW IO83

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*


On Mon, 2 Jun 2025, 18:52 Mike Hord, <[email protected]> wrote:

> Hey all-
>
> I'm trying to make a flip-dot display like this one:
> https://hackaday.com/2021/05/29/3d-printed-flip-dots/
>
> I'm having a hard time with the electromagnet component of the project. OP
> used 3mm threaded rod, and it seemed to work okay per his videos, but it's
> not working for me at all.
>
> I'm relatively sure the problem is in the permeability of the core.
> Stainless steel is not a great magnetic field conductor. I'm looking for
> something better.
>
> Lots of searching has led me nowhere. I'm thinking of trying a nail next;
> I'm wondering if anyone has any better ideas for a core? NB- I've seen the
> "soft iron core" that Amazon sells; it's a bit expensive for my taste ($16
> for 200mm; I would need four of those rods to complete the project).
>
> Mike
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