I need some way to control an Android mobile phone or iphone 5 to allow me use a external microphone in the headphone 3,5mm socket and output my voice (in real time) to an external bluetooth speaker via the mobile bluetooth system in the phone. In fact its like using a mobile phone used as a PA system. Can anyone help?
I found this app on App store that might suits your needs.
Megaphone transforms your iPhone into an instant Microphone, PA system or Megaphone when you plug it into amplified speakers.
As you plug in external microphone your system should switch to that input, same for the Bluetooth speakers as output.
No you cannot modify the white headphones you got. I'm assuming that your external mic is connected to some sort of audio panel right? If that's the case then you'll have to use an audio panel out to microphone in cable.
Or if you want a direct connection to your iPhone you could try using something like this;
AFAIK if you use something like the above image, the iPhone will detect that you're using the jack as microphone in and not mic+headset speakers So it will then reoptimize and choose your bluetooth speaker for sound out.
I had the same problem. The mic on my ipad is dead, can't figure out why and how. I don't want to purchase that expensive adapter either, but I did have a bluetooth microphone laying around. I connect my ipad to the bluetooth mic, then in order to override the internal mic, I plug the white headphone into the jack. Somehow it works.