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Discussion in 'Electronic Repair Modifications DIY' started by Link555, Jun 7, 2011.

  1. Link555

    Link555 Well-Known Member

    Ok so I am a little behind....I just got my first iphone. I am going to make a guitar input impedance matcher for the iphone. What feature would you like in one?

    I am thinking:
    IPHONE in(1/8" 4 COND)
    GTR In jack (1/4" Mono)
    Amp Out Jack(1/4" mono)
    Headphone out (1/8" 4 COND)
    DI out (1/4" balanced)

    I am planning on using 4.5v rails with 3 AAA batteries.
    I will have a simple JFET amp or opamp based circuit to do the attenuation.

    Anyone interested?
  2. Link555

    Link555 Well-Known Member

    Here is a crude Idea....
  3. Link555

    Link555 Well-Known Member

    PCB layout is complete, any suggestions before I make this thing?
  4. vttom

    vttom Active Member

    Prototype it BEFORE you commit it to PCB?
  5. Link555

    Link555 Well-Known Member

    Good Advice but I am ok with spinning my own PCBs.
  6. Boswell

    Boswell Moderator Distinguished Member

    Looks pretty good, although I think you should connect the primary circuit of the DI transformer to the input jack and not after the 100uF cap, since the inboard end is at half the supply voltage. If you were trying to avoid problems with users applying d.c. at the input, you could leave the transformer primary top end as is and take the low end (p8) to the half-supply point. The input cap polarity is reversed.
  7. Link555

    Link555 Well-Known Member

    d'oh thanks again Boswell! Will do!

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