Electret Microphone Circuit

Even though lot of MEMS Microphone available in the market an easy and affordable way to transduce sound signal into electrical signal (Audio Signal) are implementing Electret or Carbon Microphone in Circuit. When we use these Microphones we can get direct Analog audio output and also better directional Characteristics.

Electret Mic

As we know Electret Microphone is a type of electrostatic capacitor based microphone and it requires DC potential for its operation and a DC blocking Capacitor at its Electrical Audio output pin, we designed a few components preamplifier circuit for Electret Microphone. The following Circuit Contains two BC549 NPN Transistors both are Configured in Common emitter configuration. Q2 transistor Stabilized to give half the DC input supply as Output so we can get maximum peak variations in output Audio signal.

This simple Electret Microphone Circuit designed to operate using 6 volt to 30 volt DC supply but using 12V DC gives better output performance. If you are sing two terminal Electret Microphone then you can connect +Ve terminal of C1 Capacitor to +Ve terminal of Electret Mic along with R1. Here C1 Capacitor blocks DC from mic and gives low distortion audio to the base terminal of Q1. Decoupling Capacitor C2 at the emitter terminal of Q1 makes output gain high then Q2 transistor gives maximum level output through emitter terminal. C4 Capacitor grounds noise signal at the output. So we get very low noise output Audio Signal.

Carbon Microphone Preamplifier Circuit

Handheld microphone most of the time utilize Carbon Mic as a sensor, as we know Carbon Mic will have Fixed electrode, Carbon granules and diaphragm. When the sound or acoustic wave hits the diaphragm it will vibrates the Carbon granules and fixed electrode converts its vibration into electrical audio signal here amplitude of audio signal is depends on the bias applied to the mic. To get better noise free audio output we need a Carbon Mic preamplifier circuit. In the given circuit Transistor Q1 Configured in Common emitter Collector to base bias. C1 and C2 Capacitors blocks the DC bias and allows only Audio signal hence we get noise and distortion free audio output from this preamplifier circuit. We can power this circuit from 1.5V to 6V.

BOM

S.NoDesignatorValueQuantity1Microphone M1 22R1,R5,R61KΩ3 R222KΩ1 R310KΩ13C1,C510μF2 C2100μF1 C3,C4220μF24Q1,Q2BC 549C25R1,R31KΩ2 R21MΩ16C1,C210μF27Q1901418Battery1.5V1

Pinout

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2 thoughts on “ Electret Microphone Circuit ”

Dana Simison says: Can I substitute a BC547B for the BC549s in this schematic? If so what other changes should I make? husnu66tr says: better. Hih gain tansistors can be cause problems Leave a Reply Cancel reply Recent Posts Interfacing ESP32 and HC SR501 PIR Motion Sensor HC-SR501 PIR Motion Detector Guide to use In Applications Interfacing Humidity Sensor and OLED Display with Arduino nano RC Phase Shift Oscillator using op amp 741 Featured Circuits Automatic Lithium Battery Charger Circuit 12V DC to 220V AC Inverter Circuit using CD4047 Audio Amplifier Circuit Using TDA7052 DC Overvoltage Protection Circuit with Relay Featured Categories

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