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PCB for Samuel Groner's low distortion passive notch filter

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D

DNi

Member
Joined 2013
waltzingbear said:
I built a stupid little spreadsheet based on Ken Kuhn's article on Hall Networks
http://www.kennethkuhn.com/electronics/design_and_applications_of_the_hall_network.pdf

interesting to play with before building
Index of /ProAudio/Hall Network

Cheers
Alan
Click to expand...
I'm afraid the Excel formula in the cell G6 is not quite correct - if you use =1/(2*PI()*D5*(C5*0.000001)*SQRT((3))) instead, it will give you the correct notch frequency of 918.88Hz for the untuned filter.


Regards,
Braca
 
waltzingbear

waltzingbear

Member
Joined 2005
waltzingbear.com
OK, still not sure of your assumptions, probably you're better at math than me and reducing equations (not surprising). But I did find two stupid mistakes in my original file (since corrected)

one was notational about PI and the other was me being stupid. No, R*R is not 2R, oops.

Hey, if you want better coding have my sister write it, she writes code for Fermi Lab.

Anyway, I fixed my errors and the formula now gives the same results as DNI's while maintaining the original form of the equation.

Cheers and enjoy
Alan
 
Last edited:
D

DNi

Member
Joined 2013
waltzingbear said:
OK, still not sure of your assumptions, probably you're better at math than me and reducing equations (not surprising). But I did find two stupid mistakes in my original file (since corrected)

one was notational about PI and the other was me being stupid. No, R*R is not 2R, oops.

Hey, if you want better coding have my sister write it, she writes code for Fermi Lab.

Anyway, I fixed my errors and the formula now gives the same results as DNI's while maintaining the original form of the equation.

Cheers and enjoy
Alan
Click to expand...
I apologize for not having explained the expression I posted. It is a mathematical equivalent to Kuhn's Eq. (3) for the case C1=C2=C3 and R1=R2.
I've been programming all my life and when I see a mathematical formula to be programmed I instinctively simplify it for faster execution and a shorter statement.
The full formula will be needed if the effects of components' tolerances upon the filter performance are to be studied.
Incidentally, there is a neat tool for calculating resistor combinations that will be needed for tuning this filter. It certainly saved me quite a lot of time:
Excel spreadsheet finds ALL possible series and parallel resistor solutions


Regards,
Braca
 
Last edited:
H

hochopeper

Member
Joined 2009
I've attached a very simple ltspice sim of the filter network if it is of any help.
 

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