Dual Microphone Preamplifier For ADC, MCU & Arduino

The Dual Microphone Preamplifier circuit is designed to capture weak acoustic signals from two electret microphones (MIC1 and MIC2) and boost them to amplitudes suitable for microcontroller analog-to-digital converters, such as those found on an Arduino Uno. Electret microphones produce very low-voltage analog signals that are typically too faint for an ADC to sample accurately without distortion or low resolution. To solve this, the circuit utilizes MCP602 operational amplifiers (IC1 and IC2) configured to amplify the incoming AC audio waveforms. Capacitors are used throughout the signal path for AC coupling, blocking DC bias voltages while allowing the audio frequencies to pass between stages. Power management and reverse polarity protection are handled by 1N4007 diodes (D1, D2) and filtering components to protect the active circuitry from incorrect power supply connections. Transistors (T1, T2) and resistors configure the proper operating points and biasing conditions for the active devices. Additionally, indicator LEDs (LED1, LED2, LED3) provide visual feedback for power status and signal activity. The resulting amplified dual-channel analog audio signals are then routed via onboard connectors to external data acquisition systems, ADCs, or microcontroller development boards for further digital processing.