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From: mark@mips.COM (Mark G. Johnson)
Newsgroups: sci.electronics
Subject: Re: low pass high pass ckts. (Baxandall)
Keywords: low pass filters,high pass filters.
Message-ID: <43961@mips.mips.COM>
Date: 11 Dec 90 02:45:28 GMT
References: <1990Dec10.155837.17985@engin.umich.edu>
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Reply-To: mark@mips.COM (Mark G. Johnson)
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In article <1990Dec10.155837.17985@engin.umich.edu> ssave@caen.engin.umich.edu (Shailendra Anant Save) writes:
  >
  >  Is anyone familiar with "backsendall" (sp?) circuits?
  >These are low pass and high pass attenuators/amplifiers
  >that you can set to a particular frequency at both the 
  >ends and use potentiometers to increase or decrease
  >the db level.

I think you're referring to Peter J. Baxandall who developed
a "shelving" topology for use in audio tone controls.  You might
find what you're looking for in National Semiconductor's
application note number AN-64, Figures 21 thru 23.  It's reprinted
in their "Linear Applications Handbook."
-- 
 -- Mark Johnson	
 	MIPS Computer Systems, 930 E. Arques M/S 2-02, Sunnyvale, CA 94086
	(408) 524-8308    mark@mips.com  {or ...!decwrl!mips!mark}