Noise/mg-1

[Duane R Balvage]

       Hello all - 

        From what I've been reading, a lot of folks on this net are

    owners of Realistic (Moog)MG-1's - and I noticed something on

    them the other day ...


       I am doing foley work for a play going on in my area, and they needed

    the sound of "wind" - so I thought "hmm ... the MG-1 ought to work fine

    for this!" I had never used the noise source in it. Much to my dismay,

    the noise had this "thump-thump" in it! I remember reading about this

    phenomenon in a certain "digital noise generator" chip that was used

    in synths of this vintage, the noise caused by the counter resetting 

    to all 0's about every second or so. I opened up the synth, and lo and

    behold - an MM5837(?) noise chip! (i may have the #'s transposed ;-p  )

    soooo - I desoldered it, and put this circuit in it's place:


                V+
                |
                /
                \ 470k
                /
                \
                |              |\
                +---||---+-----|+\
                /  .22u  |     |  \_________________out to pin 7
              |/         /100k |  /        |
          +---|          \   +-|-/ ua741   | 
--        |   |   3904   /   | |/          |
          |   |\|        \   |             |
        -----   \        |   +----/\/\/\---+
         ---    n.c.     |   /      100k 
          -            ----- \
                        ---  / 1k
                         -   \
\                            |
                           -----
                            ---
                             -

      Don't laugh - I know, I know, it's a lowly 741, but WHO CARES!?

   It's SUPPOSED to be noisy! ;-}

   After i put it in, I fired it up, and turned on the noise generator

   with LFO'd filter cutoff, and bang! instant "wind" noises without

   the "tell-tale heart" noise along with it!


                                Just thought I'd share that!


                                                  Duane


   P.S. Anyone know of a quiet, High Quality op-amp with the 741 pinout?

        the MG-1 is FULL of 741's in the audio path (yuk). Also -

        anyone have the schematics for this thing? (MG-1)   Thanks!




  "Two nothings is nothing, thats mathematics, son...." - Foghorn Leghorn  
                      ________________________________          
                     / o o oo              o ooo o   /\          
       -------------/ ////  Duane R. Balvage   //// / /---------       
                   /    _________________________  / /      
                  / // / // /// // /// // /// / / / /      
                 /___ //////////////////////////_/ /      
                 \____\________________________\_\/        
                     
                     Intel Corporation, RA1-303
                   Portland Technology Development
       =========================================================

              Phone: (503) 613-8055    FAX: (503) 613-8261
                   E-Mail: dbalvage at ptdcs2.intel.com