This is a Simple dynamic and electret condenser microphone preamp circuit. Simple pre mic circuit that can amplify both dynamic microphone and Electret condenser microphone. So it is suitable for using the small power amplifier inside our home.
When we power a power supply into the circuit. Then, the LED1 will glow up to show a state working of the circuit. Which this circuit has worked of the input into 2 section.
- First, the electret condenser microphone.
- Second, the dynamic microphone.
First, When we use the dynamic microphone. It does not require the power supply. When a sound comes to this microphone. It will convert the sound to a tiny electric current. Then the coupling capacitor C3 passes this current in just only the sound signal to the base of Q1.
The Q1 is the amplifier transistor. It converts a small signal into a larger signal.
The output signal goes out of the collector of Q1, and the coupling capacitor C3 passes a signal out to the output terminal.
Second, electret condenser microphone is in the normal circuits. Which it requires the power supply that the current flows through it about 1mA. The R1 is a limited current resistor for the electret MIC.
When the electret condenser microphone gets the sound. Then, both C1 and C2 coupling capacitors will pass just only the sound signal to the input.
Next, the sound signal is amplified by Q1, out of the collector. Also, the larger signal flows the coupling capacitor C5 to the output.
For resistor R2, it passes the biased feedback current from the output to the input. It makes the circuit keep stable performance. The output of the circuit can be connected to the headset. Or maybe connected to any power amplifiers.
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