Hi.
Would like to set different gain for this MEMS microphone amplifier and cannot find data for the integrated marked O133 or OT33 , is supposed to be a plain preamplifier IC. Anyone knows ?

 

I think that IC is a 3.3V regulator. This allows you to feed 5V into 'Vin', or 3.3V into '3V'.
The amplifier circuit you show is described as 'external gain' meaning not on the microphone board.
Also there are no resistors on the board, only capacitors.

 

I think that IC is a 3.3V regulator. This allows you to feed 5V into 'Vin', or 3.3V into '3V'.
The amplifier circuit you show is described as 'external gain' meaning not on the microphone board.
Also there are no resistors on the board, only capacitors.

Right on both counts - it is a 3v3 reg and no resistors, only capacitors. At least according to the schematic for the product, which can be downloaded (.sch) from this page.

 

Thanks !

The supply this board uses is 3V; the MEMS device accepts from 1.5 to 3.6 V. That regulator would see action only for a 5V supply.
Would like to eliminate it to make that room available for a tiny amplifier install , to bring the output signal to 1V as it is only 50mV stock.

Unable to see the schematic at the link; it is to interpreted by a program I do not have. Thank you.