Using the MAX4466, an op-amp specifically designed for amplifier, which has excellent power supply noise rejection, and the board comes with a 20-20KHz electret microphone soldered on.On the back, we include a small trimmer pot to adjust the gain. Power supply voltage: +2.4V to +5.5V (can be compatible with for STM, for Raspberry Pi and other development board motherboards); Power supply rejection ratio: 112dB; Common mode rejection ratio: 126dB; AVOL: 125dB (RL = 100kΩ) rail-to-rail output; Quiescent power supply current: Less than 24μA; Gain bandwidth: 600kHz. The output is rail-to-rail so if the sounds gets loud, the output can go up to 5Vpp! Applications: This breakout board is best used for projects such as voice changers, audio recordingmpling, and audio-reactive projects that use FFT. Note:For the best performance, use the "quietest" supply available (on an for Arduino, this would be the 3.3V supply); For audio-reactive projects, we suggest using an FFT driver library which can take the audio input and 'translate' it into frequencies. The MAX4466 is a micropower operational amplifier optimized for use as a microphone preamplifier. They provide an perfect combination of optimized gain-bandwidth products and supply current, as well as low-voltage operation in super packages. Color: purple Material: PCB+metal Using introduction: Connect GND to ground, VCC to 2.4-5VDC. 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). 1.If the audio equipment you're using requires AC coupled audio, place a 100uF capacitor between the output pin and the input of your device. 2.If you're connecting to an audio amplifier that has differential inputs or includes decoupling capacitors, the 100uF