This is a simple preamplifier circuit for electret condenser microphone. using a LM1458 dual op amp IC. The circuit takes the audio signal rom the condenser microphone and amplifier it, so you can use the microphone as the input to some device which wouldn’t normally accept microphone level signals . Schematic Circuit of Microphone Electret Condenser Pre Amplifier The circuit requires a 6-9 volt supply. Output of the microphone amplifier can be made variable by connecting a 10kΩ potentiometer . Circuit’s gain can be increased by men perbesar the value of 47K, depending on the input sensitivity of the main amplifier system. The microphone should be housed in a small round enclosure. List componet of condenser pre-amp mic circuit Q1,Q2 : LM1458 Op-Amp R1,R2,R3 : 4.7k ohm resistor R4, R5 : 10k ohm resistor R6,R7 : 47k ohm resistor C1, : 0.22uF ceramic capacitor C2 : 1uF ceramic capacitor Absolute maximum ratings of ...