Electret Microphone Amplifier – MAX9814 with automatic gain control
This fully populated and tested board comes with a 20-20KHz electret microphone. For amplification we use the Maxim MAX9814, a special chip designed to amplify electret microphones in situations where the volume of the audio is unpredictable.
The chip of this amp is the MAX9814 and has some options that you can configure with the breakout. The default maximum gain setting is 60 dB, but can be set to 40 dB or 50 dB by connecting the gain pin to VCC or ground. You can also change the attack / release ratio from 1: 4000 to 1: 2000 or 1: 500 by default. The output of the amplifier is approx. 2Vpp max. at 1.25V DC bias, so it can be easily used with any analog to digital converter with up to 3.3V input. If you want to route it to a line input, just use a 1-100uF blocking capacitor in series (100uF sounds best).
Size: 26mm x 14mm