Audio hack:replacing electret mic with phone audio output.

henian

Prominent
Sep 26, 2017
2
0
510
This problem confused me a long time.
I'd like to feed a module with audio output from a phone's jack instead of the mic the board cames with.

As I said the board is designed to operate with an electret mic with the following specs:

Sensitivity -38dB
Load Impedance 2.2K
Operating Voltage 3V
The schematics:

1rgyu.png


The mic produces a signal that is 20mV peak-to-peak, centered around 1.5V, but anything in the [0.5V,2.5V] range should do according to the manufacturer.

I want to take out the mic and instead connect a phone's audio jack to the module.

I have two questions:

Are audio jack signals standard? What would be a normal signal coming out from an standard smartphone?
Assuming an average phone, what would be the minimum required circuit able to convert (most likely attenuate?) the audio jack output to the above mentioned levels?
Thanks.