This circuit diagram illustrates anaudio compressor for microphone signals. Its primary job is to even out the volume of your voice, making soft sounds louder and loud sounds quieter, resulting in a more consistent and professional audio output. This is incredibly useful for podcasts, voiceovers, amateur radio, or any application where microphone levels can fluctuate.
Audio Compressor for Microphone – How it works
The attached circuit diagram represents anAudio Compressor for Microphone, designed to manage audio signal levels effectively. This circuit utilizes an LM324 operational amplifier (U1) and an IN4148 diode (D1, D2) to create a dynamic range compression system, ensuring consistent audio output despite varying input levels from a microphone (MK1).
Also, the circuit begins with the microphone input, where the signal is coupled through capacitor C1 (10µF) and resistor R1 (10kΩ) to the non-inverting input (pin 3) of the first op-amp stage (U1.1). This stage, configured as a non-inverting amplifier with feedback resistors R2 (10kΩ) and R3 (10kΩ), provides initial gain. Capacitor C2 (10µF) and resistor R5 (100kΩ) form a high-pass filter, removing DC offset and noise.
Then the compressed signal is processed in the second stage (U1.2), where diodes D1 and D2, along with resistors R6 (10kΩ), R7 (12kΩ), and R8 (2.2kΩ), create a voltage-controlled gain element.This stage clips the signal when it exceeds a threshold, reducing dynamic range. The gain is adjusted by the resistor network, including R9 (220kΩ) and R10 (22kΩ), which interacts with the power supply (12V DC) via C9 (0.1µF).
After second stage, the third stage (U1.3) acts as a buffer, stabilizing the signal with resistors R11 (220kΩ) and R12 (10kΩ), and capacitor C6 (10µF). Then final stage (U1.4) amplifies the compressed signal, with feedback from R13 (10kΩ) and R14 (10kΩ), and couples it to the output (AF) through C8 (2nF) and R15 (10kΩ). A 6.2V Zener diode (D3) and capacitor C7 (47µF) regulate the output voltage.
This compressor enhances audio clarity by preventing distortion from loud inputs and boosting weak signals, making it ideal for recording or live sound applications. The LM324’s versatility and the diode-based compression ensure a cost-effective, reliable design.
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