This is a follow-up to https://electronics.stackexchange.com/questions/29099/designing-a-cable-for-bidirectional-communication-between-2-iphones-via-trrs-he

The cable in the above link successfully transmits audio from one iPhone to another.

But for some reason it fails on my Android device.

I noticed that on my iPhone if I go into sound recorder and make some noise the spectrograph lights up. if I then plug-in one end of the cable and make some more noise it has now gone silent. So it has registered that a microphone has been connected. if the resistance across the microphone si 100 ohms, it will fail to detect the microphone. However setting it at 200 ohms it successfully detects the microphone.

however if I repeat this experiment with the android device (Samsung Galaxy S2), the device never registers that an external microphone has been detected.

I have tried resistances between 50 and 800 ohm, and the spectrograph on the recorder app steadfastly picks up audio from the inbuilt phone microphone.

can anyone shed some light on this problem?

  • ... Why do this with a cable when there are free PTT apps out there?
    – rm-vanda
    Aug 3, 2012 at 12:56
  • 1
    We do have a few previous questions on people connecting external mics to various Android hardware models, this one looks like it could be the most relevant to you? How do I use an external microphone with my Galaxy Nexus?
    – GAThrawn
    Aug 21, 2012 at 9:48
  • @rm-vanda Think of the possibilities! The audio data can be modulated for file transfer to take place for example..
    – Irfan
    Sep 15, 2012 at 6:04

1 Answer 1


I understand this question has long since been asked. However I have useful information for Google-fu students and teachers.

From what I understand, iPhones by default have the TRRS 4-conductor jack. Androids, on the other hand, vary in specifications.

Quoted from here:

I'm sure android and apple are the same kind (I've used them interchangeably) though samsung android phones have two rings swapped.

More specifications related to Android, specifically the Nexus One, can be found here (with wiring diagrams). However, the application is different than what you are proposing. Still, this may help.

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