EMRFD Message Archive 2740

Message Date From Subject
2740 2009-02-25 19:09:22 Sam Morgan NEScaf modification for notch filter
Sorry if this is to off topic, but I don't seem to be able to get any helpful
input from other lists I ask on. Maybe there is a NEScaf list, but I haven't
found it.

I want to modify my (as of yet unbuilt) NEScaf filter
so it works as a notch filter, rather than as a bandpass filter.
Problem is I don't know how to do go about doing it.

Here is the original pdf for the bandpass model:

Here is the pdf for the LMF-100 chip:

there are some formulas in there that may be the key,
but they are over my abilities, at least if I want to
build this sometime this year.

TIA for any help
GB & 73
Sam Morgan
2742 2009-02-26 04:11:47 Paul VDP Re: NEScaf modification for notch filter
Hello Sam,

Try next link for data on MF100. Has a lot of math but also links to datasheet and app.notes from former type MF10. (...MF100 is just next generation of MF10, otherwise essentially the same.. Seems that the MF10 produced a bit more hiss than the MF100...)

The website from VK5BR also has a design including a MF10 configured for t-notch...

In this link, the datasheet for LMF100 from National. Has circuit example for notch-configuration at page 25.

Hope all this helps.. maybe till somebody can provide a circuit-example that resembles the NEScaf-design well enough to be more clear/specific about the necessary modifications......

Rgds & 73
Paul - on4bxz