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Old 02-03-2012, 12:08 PM
GeorgeP1111 GeorgeP1111 is offline
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Join Date: Jan 2012
Posts: 64
Default Audio Line In/Out Adapter?

I'm looking for a adapter to buy or build that would have the male 3.5mm TRRS plug (same as on the Mic/Phones that are OEM) to go into my SGP5 (or any Android Device) and have a Stereo 3.5mm out for Phones and a Mono 3.5mm In for Audio.

This technically would not be a "Line" In/Out as much as it would be a "Audio" In/Out because it would still be subject to the apps volume levels.

At first this looked easy enough, just build a break-out box and split the Mic and Phones into two connectors. But.... Not so fast "Grasshopper", there is a lot more going on here. Pins 3&4 on the TRRS are for the Mic/Button. When the OEM Mic/Phones are plugged the Android device detects the mic's impedance (resistance) about 1,800 ohms and switches to the external mic. When the button is pushed this resistance drops to about 97 ohms and the device detects that as a button push. Pretty neat.

I have various items plugged into my PC's soundcard. I now I have a few similar apps for the SGP5 and would rather hardwire the audio inputs vs using the internal mic. There are a few "cheats" I could do like build the break-out box and cut up a Mic/Phone using just the mic for acoustical coupling, which I may do for now.

Anyhow, sorry for getting so wordy here. Has anyone seen any adapters or schematics that might be useful?

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