The operating principle is as follows:
Resistors R1, R3 is used to adjust the gain, which equals 25. To increase the gain by 75 to build a resistance of 68 ohms. It is not recommended to install too high gain, because it may affect the sound quality, although this depends on the microphone. Capacitors C5 and C6 are used for suppression of feeding.

This circuit has been tried on three microphones, one from SONY, and then two Chinese, everything works! With the correct assembly of the device starts to work immediately, and does not need tuning.

Parts list :
R1, R3 : 220
R2, R4 : 1K5
R5, R6 : 6K2
R7 : 470
C1, C2, C3 : 0.1uF
C3, C4, C7, C8 : 10uF/10V
C5 : 470uF/15V
DA1 : K548UN1

The post Microphone Amplifier based K548UN1 appeared first on Amplifier Circuit Design.