Feature: 1. For amplification, we use the MAX4466, an op amp designed to accomplish this delicate task. 2. With excellent power supply noise rejection, so this amplifier sounds really good and isn't nearly as noisy or scratchy as other mic amp breakouts we've tried. 3. You can set the gain from 25x to 125x, perfect for reading from a microcontroller ADC. The output is rail‑to‑rail so if the sounds gets loudly, the output can go up to 5Vpp. 4. For the best performance, use the "quietest" supply available. The audio waveform will come out of the OUT pin. The output will have a DC bias of VCC/2 so when its perfectly quiet, the voltage will be a steady VCC/2 volts (it is DC coupled). If the audio equipment you're using requires AC coupled audio, place a 100uF capacitor between the output pin and the input of your devices. If you are connecting to an audio amplifier that has differential inputs or includes decoupling capacitors, the 100uF cap is not required. 5. Using it is simple: connect GND to ground, VCC to 2.4-5VDC. 6. The output pin is not designed to drive speakers or anything but the smallest in-ear headphones, you'll need an audio amplifier (such as our 3.7W stereo amp) if you want to connect the amp directly to speakers. Specification: Item Type: Microphone Amplifier Module Power Supply Voltage: + 2.4V to + 5.5V (can be directly connected for STM /for Raspberry Pi and other development board) Power Supply Rejection Ratio: 112dB Common Mode Rejection Ratio: 126dB AVOL: 125dB (RL = 100kΩ) Rail-To-Rail Output Static Supply Current: