2021-01-15   12:00:02 

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aimg_Morse-Man.jpg                     Advanced version
                           AFX 'V'ariable    

_________________________ this is the Best-of-Class Design    

******* below  are pages for   the  AFX-Variable circuits  
******* with single resistor control of the band-pass center-freq from 600Hz-to-700Hz-to-800Hz.
******* Manual control (1RL-Manual Control)  (..)   (3RL-Manual Control)     
******* FET control      (1RL-Fet Control)         (..)   (3RL-Fet Control)   

******* ----------------------------------------------------------------------------

******* below  are pages for   the  test system AFV circuits, 
******* with single resistor control of the band-pass center-freq from 600Hz-to-700Hz-to-800Hz.
******* More test/developmental versions of the AF'V' series.
*******  ( AFV-3RL-2VF-VQ ) two MFB filters simple design  
*******  ( AFV_F8AFQtwo MFB Filters with 8 All-Pass stages in the middle.  
*******  below are pages of TESTS with multiple plots generated all at one time for comparison
*******  ( AFV-1RL-V4F-D-test-F3 Single Roof )      ( AFV-
-V4F-D-test-F3 Triple Roof)   
( AFV-1RL-V4F-D-test-FM   multiple Dual-Notch adjustments )


*******  Goals achieved in AFX-V :
***   (1) Simpler design,
***   (2) Simpler construction,
***   (3) Simpler adjustment.
***   (4) better performance than original AFX design.

*** Designed from building-block modules  
*** Designed to be very easy to tune to f(600) f(700) f(800) continuous.
*** Designed so that the f(0) for the Quad Filters can be easily adjusted by user.
*** Designed so that the Q=20 Sharp Filter is variable.
*** Designed so that the Dual-Notches are < -60 dB and the Stop-Band < -100 dB.  

*** Design choices: 
*** Simple repetitive application of Modified Deliyannis-Multi-FeedBack topology. 
*** Multi-FeedBack topology was chosen because :
***    (1) input vs output impedances match well, loading is controlled. 
***    (2) single resistor frequency control each stage.
***    (3) frequency adjustments alters gain by only the square-root of the f(change) . 
***    (4) the Roof-Triad-Differential design provides superior side-band suppression.
***          and is wide enough to be very tolerant of component variations,

MFB_BPF_equations_TI_.png  Just for reference.


*** Below,  "AFX-V-3rl-v4F-D-vQ-Fet"
the    "AFX-V-3RL-v4F-D-vQ-Fet"  
Best-of-Class design  

*** This circuit utilizes  Three Triad-Roofing-Differential Filters
*** The capabilities of the Triad-Roofing-Differential Filters are explored
on the Roof Pages  }. 

*** Dual-Notches are very Deep and Octave Stop-Band very low. 
*** Main Filter f(0) is Variable 600 - 700 - 800   by user  in real-time.  
*** Sharp Q=20 filter is variable within the selected PassBand.
*** Here, the R(freq) is currently controlled by one R(freq) Pot, mounted on the front panel, for real-time control.
*** The Four FET controllers are driven by a single Voltage Source, controlled by a Panel Mounted Pot.
*** Front Panel Rotary Switch allows User to send any stage into the Audio Section.
*** Front Panel Switch enables FxQ20 to be used following any stage.


****"AFV-3RL-v4F-D-vQ-Fet" adjusted 600Hz , 700Hz , 800Hz


***********************************   Notice that the  600 - 700 - 800 waveforms  have good BandPass shapes. 
**** the very wide signal is the Roofing Filter Output, which will contain the variability of the central f() signal


***** Notice that at all three frequencies, the peak amplitude of the final signals stay within 0.3 dB of the f(700) signal. 

******* Magnitude Plot for AFV-3RL-v4F-D-vQ-Fet




  ******* Manual Tuning  via Four 5K rear-panel mounted pots.

    ******* designed to control all four Filter f(0), 600 Hz to 800 Hz, manually, for initial set-up.

    ******* this is the simplest approach and should be utilized for the Club Kit Project.



The below 'test circuit' and plots are NOT spectacular
but were given a fair test.

... Goal was to test use of only Two MFB filters . 

... Dual Notches could not be well developed when using only Two MFB filters.
...    More phase alignment is required to generate the Dual Notches.
...    Therefore, No notches are presented in the below plots.

... Adjustable in real-time from 600Hz continuous to 800Hz
       by a single front-panel mounted 5K Pot for User Real-Time Control.  



*** AFV_3RL-v2F-vQ-v1-S  design : 
***  (1) with Three Roof Filters 
***  (2) with only Two MFB filter stages 
***  (3) with R(freq) controlled by a Two-Gang Pot 


*** Bode Plot shows good regular BW measurements -3dB to -12dB down. 

*** Magnitude Plot shows reasonable bottom end attenuation ... Plus / Minus Octave.
*** Q20 (red) is the sharp bandpass.
*** Phase Alignment is not sufficient to produce Dual-Notch.