
                              EXAMPLE CIRCUITS
                              ----------------




                      3              4                      5
              Input   O------||------+------||------+-------O   Output
                            50uF     |     50uF     |
                                     *              |
                                     * 2.5 mH       |
                                     *              |
     HPFILTER                        |              * 
     ========                      1 +              * 8 Ohms
                                     |              *
                                     *              |
                                     * 0.2 Ohm      |
                                     *              |
                      2              |              |       2
                      O--------------+--------------+-------O   Common
  




                                                                      5
                  +--------+--------------------+---------------------O
                  |        |                    |                     HT
                  |        |                    |
                  |        |                    *
                  |        *                    * 10k
                  |        * 130k               *
     FBAMP        *        *                    |
     =====        * 330k   |       20pF       8 |                     7
                  *        |     +--||--+-------+-------||------+-----O
                  |        |     |      |       |      330nF    |    O/P       
                  |        |     |      |    |--+               |
                  |      4 +-----+-----------|    TR2           |
                  |        |            |    |->+               |
         1        | 2   |--+            |       |               |
         O---||---+-----|    TR1        |       |               |
     I/P   330nF  |     |->+            |       |   6           *
                  |        |     33k    |       +---+           * 47k
                  |      3 +----****----+       |   |           *
                  |        |            |       |   |           |
                  *        +-----||-----+       *   |           |
                  * 22k    |    270pF        2k *  --- 100uF    |
                  *        *                    *  ---          |
                  |        * 1k                 |   |           |
                  |        *                    |   |           |
                  |        |                    |   |           |
         O--------+--------+--------------------+---+-----------+-----O
                  5                                     Common 




                                      MUTUAL
                                 k=0.03/.015/.005
             1    100k    4                                      2
             O----****----+----------+     +----------+----------+------O
            I/P           |          |     |          |          |     O/P
                          |          * ||| *          |          |
                          |     20uH * ||| * 20uH     |          |
    DUBTUNE               |          * ||| *          |          *
    =======              ---         |     |         ---         * 30k
                         ---         |     |         ---         *
                     317p |          *     *          | 317p     |
                          |     2.2R *     * 2.2R     |          |
                          |          *     *          |          |
                          |          |     |          |          |
              O-----------+----------+-----+----------+----------+------O
                          3                      Common







                                          110
                             +------------***-------------+
                             |                            |     
                             |                            |     
                I/P   110    |   100p          3 |\       |     
                O-----***----+----||---+---------|+\      |     
                1            | 2       |         |  \   5 |    O/P   
                             |         |         |   >----+------O
                             |         |       4 |  /     |     
                             |         |     +---|-/      |     
                             |         |     |   |/       |     
                             |         *     |            |
                       100p ---    220 *     |     5p     |     
                            ---        *     +-----||-----+     
                             |         |     |            |     
                             |         |     +----****----+
       BANDPASS              |         |     |     511
       ========              |         |     *
                             |         |     * 261
                             |         |     *
                             | 6       |     |
                 O-----------+---------+-----+-------------------O
                                     Common 


                                                           4      250V
                                                  ---------+---------
        1     2.8144773234uF     2                         |
        O----+------||------+----O                         *
       I/P   |              |   O/P                        * 10k
             |   100.0mH/   |                              *
             +-----****-----+                              |
                0.0001 Ohm  |                            6 +
                            |                              |
                            *                              *
        NOTCH300            * 3553.0931153                 * 100uH/1.0
        ========            *        Ohm                   *
                            |                              |           O/P
                            |                            2 +-----||-----O
        O-------------------+----O                         |    .01u    5
              Common       3                  I/P   1    --+--
                                               O----+---+- - -
                                                    |    [---]   ECC83/12AX7
                                                    |        |   -----------
                                                    |        |
                                                    *      3 +-----+
                                      VALVEAMP      * 1M     |     |
                                      ========      *        *    --- 10u
                                                    |   1.6k *    ---
                                                    |        *     |
                                                    |        |     |
                                               O----+--------+-----+----O
                                                       Common      4





               1    6k8                                         2
               O----***----+--------+--------+--------+---------O
              I/P          |        |        |        |        O/P
                           *        *        *        |
                           * 3k     * 1k     * 300    |
                           *        *        *        |
                           |        |        |        |
                         3 +      4 +      5 +       ---
      WHITEPNK             |        |        |       --- 33nF
      ========            ---      ---      ---       |
                          ---      ---      ---       |
                           | 1uF    | 270nF  | 94nF   |
                           |        |        |        |         6
               O-----------+--------+--------+--------+---------O
                                    Common 

                                                             3
                                                -------------+------+-----
                                                             |      |
                    3                                        |      *
       -------------+------+-----                            *      * 2.2k
                    |      |                            100k *      *
                    |      *                                 *      |    O/P
                    *      * 2.2k                            |    7 +-----O 
               100k *      *                                 |      |
                    *      |    O/P               |        8 |   |--+
                    |    2 +-----O              3 +----||----+---|
                    |      |                      |    1u    |   |->+
  I/P       4     5 |   |--+                                 *      |
   O---***--+--||---+---|                                47k *      + 2
   1   2.2k    1u   |   |->+                                 *      |
                    |      |               I/P       4     5 |   |--+
                    |    6 +----+           O---***--+--||---+---|
                    *      |    |           1   2.2k    1u   |   |->+
                27k *      *   ---                           |      |
                    *   1k *   ---                           |    6 +----+
                    |      *    | 10u                        *      |    |
                    |      |    |                        39k *      *   ---
     ---------------+------+----+---                         *   1k *   ---
            Common         3                                 |      *    | 10u
                                                             |      |    |
        R35 = 100k || 27k = 21.3k              --------------+------+----+---
                                                     Common         3
 
                  VIDEO1                                   VIDEO2
                  ======                                   ======



       I/P                       |\
        O-----+---+--------------|+\
        1     |   |              |  \                       4.3k       O/P
              *  ---             |   >------------------+---****---+----O
          47k *  --- 100p        |  /                 3 |          |    8
              *   |          +---|-/                    |          |
              |   |          |   |/                     |          |
            --+---+-- 7      |        4   11k  5  160k  |         ---
             Common        2 +--****--+--****--+--****--+         --- 1500p
                             |   1k   |        |        |          |
                             *        +---||---+---||---+          |
                             * 330       6800p   .022u             |
                             *                                   --+-- 7
                             |
                           6 +
                             |
                            --- 100u             RIAA
                            ---                  ====
                             |
                           --+-- 7 


  
 I/P  12mH/.5      O/P     55u  0.6mH/1.2    O/P       4u     5u     0.5R   O/P
  O---****--+---+---O   O--||--+--***--+---+--O     O--||--+--||--+--***--+--O
  7         |   |   6   7      | 5     |   |  4     7      | 3    2       |  1
            |   |              |       |   |               |              |
           ---  *              *      ---  *               *              *
      100u ---  * 8     8mH/.5 *   5u ---  * 8    0.18mH/2 *              * 8
            |   *              *       |   *               *              *
     Bass   |   |              |  Mid  |   |               |    Treble    |
     ----   |   |              |  ---  |   |               |    ------    |
  O---------+---+--------------+-------+---+---------------+--------------+--O
                                    Common                 8
               CROSSOVR
               ========




            2    1k    1    1k    3    1k    7           |\
            O---****---+---****---+---****---+-----------|+\  LF355
           I/P         |          |          |           |  \
                       |          |          |           |   >----+-----O
                40.9n ---   258n ---     1n ---          |  /     |    O/P
  LPACTFIL            ---        ---        ---     +----|-/      |
  ========             |          |          |      |    |/       |
                       |          |          |      |             |
            O----------+---------------------+--------------------------O
              Common   4          |                 |             |
                                  +-----------------+-------------+
              Node 5 not used                       6





                           +------*****-----+
                           |       10k      |
                   I/P     |    |\          |
                    O------+----|+\         |
                    1           |  \        |     O/P
                                |   >-------+------O
                                |  /        |      2
                            +---|-/         |
                            |   |/          |       
                        3   |      10k      |
                        +---+-----*****-----+
                        |   |
                       ---  *
               1.5915n ---  * 10k        NIC
                        |   *            ===
                        |   |
                  4 ----+---+----
                       Common 


                      2                                               10   1
              +-------+-------+---------------+------+------+-------+-***--O
              |       |       |               |      |      |       |     22V
              |       |       |               |      *      |      --- 
              |       *       |               |      * 22k  |      --- 470u
              *       * 1k5   |               |      *      |       |
           1M *       *       |               *      |      |      -+- 1
              *       |       |           1M  *   21 +----------+ 
              |       |       |               *      |      |   |
              | 4p7   | 5  |-<+               |      *      |  ---
            4 +--||---+----|     TR2          |      * 62k  |  --- 330u
              |       |    |--+               |      *      |   |     
              |       |       |               | 2p2  |   |--+   |
         4k7  |    |--+       |            18 +--||--+---|      | TR4
   24 +--***--+--->|    TR1   |               |      |   |->+   |
      |       |    |--+       |               |      |      |   |   3u3    O/P
     ---      |       |       |         .47u  |   |--+19    +---+---||---+--O
     ---      |       |       |       +--||---+---|        22   |        |  23
      |.068u  |       +-------+ 6     |       |   |->+          *        |
 I/P  |       |       |       |       |       |      |          * 1k     |
  O---+       *       |       |       |       |  TR3 |   20     *        *
  3   |       * 1M    |       |       |       *      +---+      |        * 10k
      |       *       *       *       |  120k *      |   |      +-----+  *
      *       |       * 160   * 5k6   |       *      *   | 3u3  |     |  |
      * 100k  |       *       *       |       |  20k *  ---     *     |  |
      *       |       |       |       |       |      *  ---     * 220 |  |
      |       |       |       |       |       |      |   |      *     |  |
      |       |       |       |       |       |      |   |      |     |  |
   O--+-------+---------------+---------------+------+---+------+--------+--O
   1    Common        |               |                               |
                      |               |                               |
                7 +---+               |    TREBLE                     |
                  |                   |    ~~~~~~                     |
                  |       4300p   2k  |   25k pot     2k     4300p    |
                  |    +---||--+--***--+--***^***--+--***--+--||---+  |
             10u ---   |       9      |10    |     12      13      |  |
                 ---   |              |      |11                   |  |     
                  |    |              +------+---------||----------+  |
                  |    |                     |         75p         |  |
                  |    |                     *                     |  |
                8 +----+                     * 12k                 +--+ 14
                       |                     *                     |
                       |              .03u   |   .03u              |
                       |          +----||----+----||----+          |
                       |          |          |16        |          |
                       |          | 15       |       17 |          |
        BAX            +---***----+------****^****------+----***---+
        ===                12k           100k pot            12k
 
                                           BASS
                                           ~~~~

             TR1 : BF245A       TR2 : BCY71        TR3 & TR4 : BC109 






      1      5.968k      2             1.989k   7          |\
      O-------****-------+---------+----****----+----------|+\
     I/P                 |         |            |          |  \          8
                         *         |            |          |   >----+----O
                         * 3.978k  |     1000p ---         |  /     |   O/P
                         *         |           ---     +---|-/      | 
                         |         |            |      |   |/       |
      +------------------+ 3       |            |      |            |
      |                  |         |   |\     --+--    |            |
      |                  *         +---|+\      9      +------------+
      |                  * 3.978k      |  \
      |                  *             |   >----+
      |       /|         | 4           |  /     |
      |      /-|---------+-------------|-/      |
      |     /  |         |             |/       |
      +----<   |        ---                     |
            \  |        --- 1000p               |
             \+|---+     |                      |
              \|   |   5 +----------------------+
                   |     |
                   |     *
                   |     * 5.303k
                   |     *
                   |     |                          GYRATOR
                   +-----+ 6                        =======
                         |
                        --- 1000p
                        ---
                         |
                         |
                     9 --+-- Common 




                     20k pot
          10 +-----****^****------------------------+ 20
             |         | 1..9                       |
             |        ---                           |
             |     Cb ---                           |    No     Ca       Cb
             |         |    470            21..29   |    --     --       --
             |  11..19 +---****----------------+    |    1   0.152u    8.590u
             |         |                       |    |    2   0.061u    3.440u
             |        ---                      |    |    3   0.024u    1.380u
             |        --- Ca                   |    |    4    9750p    0.550u
             |         |              |\       |    |    5    3900p    0.220u
             |  31..39 +--------------|+\      |    |    6    1560p    0.088u
             |         |              |  \     |    |    7     624p    0.035u
             |         *              |   >----+    |    8     250p    0.014u
             |         * 62k          |  /     |    |    9     100p     5600p
             |         *          +---|-/      |    |
             |         |          |   |/       |    |          Q = 1.7
             |     41 -+-         |            |    |       Variation 12dB
             |        Common      +------------+    |
             |                                      |
             |                                      |
             |             STAGES 1..9              |
             +-- - -                          - - --+ 
             :                                      :
             :                                      :
             +-- - -                          - - --+           3.3k
             |                                      |      +----****----+
             +-- - -                          - - --+      |            |
             |                                      |      |   |\       |
 I/P         |                                      +------+---|-\      |
  O---****---+                                                 |  \     |   O/P
  30  3.3k   |                                                 |   >----+----O
             |                                                 |  /     40
             +-------------------------------------------------|+/
                                                               |/


                                 GRAPHEQ
                                 =======



   Refs.  (i)    Audio/Radio Handbook - National Semiconductor 1980  p2-61
          (ii)   Maplin Electronics Magazine No 71 Nov 1993  p61
          (iii)  Multisection Tone equalizer - Wireless World June/July 1980 


 2        3       4       5       6             47      48      49      50
 O---***--+--***--+--***--+--***--+- - - - - - -+--***--+--***--+--***--+---O
I/P  L/2  |   L   |   L   | L=2uH |             |   L   |   L   |  L/2  |  O/P
          |       |       |       |             |       |       |       |
          |       |       |       |             |       |       |       * 
         --- C   --- C   --- C   --- C=200pF   --- C   --- C   --- C    * 100
         ---     ---     ---     ---           ---     ---     ---      * Ohm
          |       |       |       |             |       |       |       | 
          |       |       |       |    n=47     |       |       |       | 
          |       |       |       |             |       |       |       | 
 O--------+-------+-------+-------+-------------+-------+-------+-------+---O
          1                                                  Common

          LINE           Zo = SQRT(L/C) Ohms     Delay = n*SQRT(L*C) secs
          ====


                                             10
           ---------+-------+-------+---------+-------------+--------- HT
                    |       |       |         |             |
                    |       |       |         *             |
                    |       |       |         * 300R        |
                    |       |       |         *             |
                    |       |       |         |          |--+
                    |       |       |       8 +----------|
                    |       |       |  10     |          |->+
    I/P2  100R      |    |--+       |   |  |--+             |
     O----****---+-------|          |   +--|                |
                 4  |    |->+       |   |  |->+             |            O/P
                    |       |       |         |           9 +----+---||---O 
                    |       |       |         |             |    | .01uF  11
    I/P1  100R   |--+     5 +------------------------+      |    |
     O----****-+-|          |       |         |      |      |    |
     1         2 |->+       |       |         |      |      |    |
                    |       |    |--+       7 +--|   |      |    |
                  3 +------------|               |---+      |    |
                    |       |    |->+         +<-|          *    | 5pF  
                    |       |       |    6    |        270R *   ---
                    |       |       +----+----+             *   ---
                    *       *            |                  |    |
     WBAMP     4.3k *  4.3k *          |--+                 |    |
     =====          *       *       +--|         2N5179     |    |
                    |       |       |  |->+      ------     |    |
                    |       |       |     |                 |    |
                    |       |       |     |                 |    |
        ------------+-------+-------+-----+-----------------+----+-------
                   Common                 10

 I/P2 : Join to common for normal response & to I/P1 for common mode response.


                                               CIRCUITS(52).TXT       03/02/96
