Hi,
I heard that Microphone input in smartphones provide some DC voltage for different needs(let's say connect external microphone circuits) If this true, does somebody know parameters of this source: voltage and current abilities
Thank you in advance
The article below gives some info. From the looks of it, the contacts are specific (2 or 3 or 4 conductor), and their functions are specific to whatever model you have, so that you can't easily expect to find out the parameters. If I had a smartphone, I would not want experiment with its electrical characteristics. I'd be afraid of ruining a valuable piece of equipment.
Most modern portable microphones are the electret type ( look it up ion Google). They have a Jfet inside to reduce the extremely high impedance to a useable impedance and the Jfet is powered by a voltage from 1.5V to 5V at a current of about 0.5mA.