Using the MAX4466, an operational amplifier specifically designed for amplifiers, which features power supply noise reduction, and the board comes with a 20-20KHz electret microphone soldered on. On the back, there's a small trimmer potentiometer to adjust the gain. Power Supply Voltage: +2.4V to +5.5V (can be compatible with for Arduino, 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 Current: Less than 24A; Gain Bandwidth: 600kHz. The output is rail-to-rail so if the audio gets loud, the output can go up to 5Vpp! Applications: This breakout board is best used for projects like voice changers, audio recording, and audio-reactive projects that use Arduino. Note: For best performance, use the quietest available power supply (on an Arduino, this would be the 3.3V supply); For audio-reactive projects, we suggest using a driver library that can take the audio input and 'translate' it into frequencies. MAX4466 is a low-power operational amplifier optimized for use as a microphone preamplifier. They provide a perfect combination of optimized gain-bandwidth products and quiescent current, as well as low-voltage operation in super packages. Color: Purple Material: PCB+Metal Usage 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 it is completely silent, the voltage will be a steady VCC/2 volt (it is DC coupled). 1. If the audio equipment you are using requires AC-coupled audio, place a 100uF capacitor between the output pin and the input of your device. 2. If you are connecting to an audio amplifier that has differential inputs or includes decoupling capacitors, the 100uF capacitor is not required. 3. If you want to connect the amplifier directly to speakers. If you are connecting to a microcontroller pin, you do not need an amplifier or decoupling capacitor - connect the OUT pin directly to the microcontroller's ADC pin. Note: The output pin is not designed to drive speakers or anything other than the smallest in-ear headphones - you will need an audio amplifier (like a 3.7W stereo amplifier) For audio-reactive projects, we suggest using a driver library that can take the audio input and 'translate' it into frequencies. Applications: It is widely used in mobile phones, digital repeaters, headphones, hearing aids, microphone preamplifiers, laptops, speech recognition systems. Package Contents: 5 x MAX4466 Module (Due to computer display, the color of the product may differ from the image) 5 x Pin Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture to be a little different from the real thing. The allowed measurement error is +/- 1-3cm.