    





    2600 ~o~ TO 6~' 1'~ SU"LY
     IN | ~ TO "`Jl~7® V.3vr,lt ~ _
    
                                        ~;  ~DIO 2
    
    ~L~
    _~
    
    ~1
            Tø ~THER
            au7~o~s
    
    NOTES
    
    This mixer-ampllfier uses 24 diodes to
    produce 12 separate tone pairs without
    mixing them at their source. Each
    diode is silicon, low current, and the
    pair should be matched if possible. A
    single pure tone needs no diodes, of
    course.
    A telephone earpiece is a perfec~, low
    cost speaker for this unit, and has the
    added advantage of coupling tightly with
    a telephone mouthp~ece if yon want to
    play this instrument to your friends,
    over the phone.
    A 50K ohm trimmer tunes each oscillator.
    All parts in this project are 10% or
    better tolerance, but the capacitors
    should be drift-free types(mylar, epoxy,
    or mica), or else the oscillators will
    detune easily.
    Two bstteries are recommended for ease
    of construction and stability of tone.
    
    ~STO,S - 10ø~
    DI0055 -~7`UE.
    5~ SiCN4L
    
    a~no~s ' SPSt ~.
    
                          AMp 7~.~ S8~
    
    *276B016
    
    TE~
    EARPIECE
    
    _ _ Ä_Ä .
    
    , l
       L
       t10
    
                      ~60~.        ~
                      is lo~T . ~ MFO,
    
    This simple mlzer and amplif ier can
    be used in the e. lectranic organ de -
    scribed last iseue . 1 ) Power to the
    speal~er will be lost at low frequen-
    cies if a sultable enc lo~ure is not
    used. A small metal 3r plastic box
    is fine. The box can, of c~urse,
    contain the rest of the parts. Tones
    can be f~und for sultable notes ln
    any sonnd engineering manual.
    
    2) {f played into the phone [or any
    reason, the speaker should be lined
    with a circle of f~am to form a good
    seal that is held tightly to the
    mout hp ie ce .
    
                       ylpp~re bOred ø
    
    WestlOdnl ke to
    ni gdh tt~ 2 4 5 - 1 5 0 0
    
    1' '1
    ~i
    
    