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: http://newenglandqrp.org/files/NEScaf_200803.pdf Here is the pdf for the LMF-100 chip: http://newenglandqrp.org/files/NEScaf_200803.pdf 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 KA5OAI 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...) http://www.swarthmore.edu/NatSci/echeeve1/Ref/FilterBkgrnd/SwitchedCap.html The website from VK5BR also has a design including a MF10 configured for t-notch... http://www.qsl.net/vk5br/SwCapFilter.htm In this link, the datasheet for LMF100 from National. Has circuit example for notch-configuration at page 25. http://www.national.com/ds/LM/LMF100.pdf 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 ________________________________

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:
http://newenglandqrp.org/files/NEScaf_200803.pdf

Here is the pdf for the LMF-100 chip:
http://newenglandqrp.org/files/NEScaf_200803.pdf

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
KA5OAI
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...)
http://www.swarthmore.edu/NatSci/echeeve1/Ref/FilterBkgrnd/SwitchedCap.html

The website from VK5BR also has a design including a MF10 configured for t-notch...
http://www.qsl.net/vk5br/SwCapFilter.htm

In this link, the datasheet for LMF100 from National. Has circuit example for notch-configuration at page 25.
http://www.national.com/ds/LM/LMF100.pdf

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

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