Condenser Pre Amplifier LM 1458

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 LM 1458 IC

Supply Voltage               :  ±18V

Power Dissipation            : 400 mW

Differential Input Voltage   : ±30V

Input Voltage                : ±15V

Output Short-Circuit Duration: Continuous

Operating Temperature Range  : 0°C to +70°C

Storage Temperature Range    : −65°C to +150°C

Lead Temperature             :(Soldering, 10 sec.) 260°C