Connect Morse Key to Iphone

How to connect morse key to an iPhone? Using the buttons on the standard headphones does not work, as the apple interface does not provide low-level access to low-level events like button-down. The idea (R1, R2) will be (1) put a signal to one stereo channel (2) receive the same signal on the input channel (small resistor will simulate mic) (3) detect tone level changes for input channel -> real time-morse (4) put side-tone & co to remaining stereo channel.

Pasted Graphic

  • 1(Tip) – Key (Ground)
  • 2 – Ear (Contact)
  • 3 – Ear (Ground)
  • 4(Ground) – R2(46,6k) – Key 1
  • 4(Ground) – R3(22k) – Key 2
  • 4(Ground) – R1(1k) – 3

I got a prototype running with irmc-ios (R4) and the same physical interface also works with iMorsix (R3).
IMG_0188

(R1) Hijacking Power from […] Audio Interface
(R2) Sources: hijack-main
(R3) App: iMorsix
(R4) App: irmc-ios

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3 Comments on “Connect Morse Key to Iphone”

  1. Xander Langschmidt says:

    Hi Gerolf,

    I would be interested to hook up my key to iMorsix, but I get a little lost in your description. To my best knowledge the tip (1) is left audio (2) is right audio, (3) is ground and (4) is mic. Now from the text above I understand that I have to connect my key between 1 of the audio channels and the mic in series with a resistor, but that is as far as I understand the above. Any change you can put a simpler description or even a small schematic?

  2. Fabio Nicora says:

    Hi Gerolf, very interesting! Could you please share the electric scheme to understand a little bit better electric connections? Thanks. Fabio

  3. gerolfziegenhain says:

    Hi Xander,

    The schematic is the list, i.e. “4(Ground) – R2(46,6k) – Key 1” means connect 4 with R2 with Key 1.


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