Add an ear to your project with this well-designed electret microphone amplifier. This fully assembled and tested board comes with a 20 Hz–20 kHz electret microphone soldered on. For amplification, we use the Maxim MAX4466, an op-amp specifically designed for this application. The amplifier has excellent power supply noise rejection, delivering clean audio output with low noise. This breakout is suitable for projects such as voice processing, audio recording/sampling, and audio-reactive applications using FFT. A trimmer potentiometer on the back allows gain adjustment from 25× to 125×. The output signal ranges from approximately 200 mVpp (for normal speech at 6 inches distance) — suitable for line-level inputs without clipping — up to about 1 Vpp, ideal for microcontroller ADC input. The output is rail-to-rail, capable of reaching up to 5 Vpp with loud input signals. To use: connect GND to ground and VCC to a 2.4–5 V DC supply. For best performance, use a low-noise power source (e.g., the 3.3 V supply on an Arduino). The audio waveform appears at the OUT pin. The output includes a DC bias of VCC/2, meaning the quiescent voltage is steady at VCC/2 when no sound is present (DC-coupled output). If your downstream audio equipment requires AC-coupled input, place a 100 µF capacitor between the OUT pin and the input of the device. This capacitor is not needed if the receiving device has differential inputs or built-in decoupling capacitors. The output pin is not intended to drive speakers or headphones directly — an external audio amplifier is required for speaker-level output. When connecting to a microcontroller analog input pin, no additional amplifier or decoupling capacitor is required.