[sdiy] Weird Serge Resonant Filter topology in upper bands

[Lanterman, Aaron D]

> On Dec 15, 2022, at 2:56 AM, Guy McCusker <guy.mccusker at gmail.com> wrote:
> 
> Isn’t Rod Elliott’s Fig 7 exactly what Don drew?

Yup! But it looks like if you try it with the values given in the Serge Resonant Filter schematic it’s not quite peaky enough. Rene’s trick of flipping the + and - inputs gives the correct Q.

Now, I tried the Elliott/Don schematic with the values in the Elliott schematic and it did give a super peaky filter. I guess the devil is in the details of what values you pick.

Although, it kind of boggles my mind that the filter operates in a linear fashion either way. I’d think that one of the ways should make it freak out and either rail out or turn into an oscillator. I still feel like I’m missing something.

Aaron Lanterman, Prof. of ECE, Georgia Tech
My blog on Education and Innovation: https://edupocalypsenow.wordpress.com
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