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 = 100k) rail-to-rail output; Quiescent power supply current: Less than 24A; 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 cap is not required. 3.If you want to connect the amp directly to speakers. If you're connecting to a microcontroller pin, you don't need an amplifier or decoupling capacitor - connect the OUT pin directly to the microcontroller ADC pin. Note: 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 3.7W stereo amp) For audio-reactive projects, we suggest using an FFT driver library which can take the audio input and 'translate' it into frequencies. Applications: It is widely used in Cellular phone, Digital repeater, Headphones, Hearing aids, Microphone preamplifier, Portable computer, Speech recognition system ect. Package Contents: 5 x MAX4466 Module(Due to the computer display, the color of the product may be different from the picture) 5 x Pin Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. _x000D_ _x000D_ _x000D_ _x000D_ _x000D_ _x000D_