
Inductor resonance and self-resonance experiments (2016) - userbinator
http://g3ynh.info/zdocs/magnetics/appendix/self_res/gallery.html
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agumonkey
His page on variable inductors had me going "ohhh" quite a few times.

If anybody knows about non mechanical / solid state variable caps / inductors,
I was trying to find how to learn about them.

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hatsunearu
> solid state variable caps

Varicaps are only good for low power and are kind of nonlinear, but it's a
voltage controlled capacitance.

I think for lower frequencies, a capacitor bank that's switched is the best
bet.

In terms of inductors, AFAIK other than an inductor matrix it doesn't exist,
but i think you can build a virtual inductor using a GIC.

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jackyinger
Diodes exhibit capacitance that varies with respect to their DC bias. I know
this is used in GHz RF applications.

Using opamps to create virtual reactive components (capacitors, or inductors)
that would otherwise be impractical to build directly (too high of value) is
an interesting trick.

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hatsunearu
> Diodes exhibit capacitance that varies with respect to their DC bias. I know
> this is used in GHz RF applications.

Oops, I meant to say varactor, not varicap. And this is used for VHF and up as
well.

The GIC-based filters are used a lot for high-Q parametric filters often in
audio or general scientific stuff.

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PoachedSausage
Thanks for reminding me about this. His whole website is practically a
reference text for RF engineering, now is the perfect time to dive back in.

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amelius
You can also simulate these kind of experiments using EM solvers.

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PoachedSausage
Are there any particular ones that you would recommend?

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madengr
I use CST often, and used it for helical resonators, specifically the
Eigenmode solver. The latest version should do an eigenmode analysis with open
boundaries, which you’d need for coils. My resonator was in a cavity.

