Various types of basic electronic projects using operational amplifier based projects is already posted in www.bestengineeringprojects.com. Now, here is one another basic projects using operational amplifier called microphone amplifier using 741. The circuit microphone amplifier amplifies weak electric signal converted by microphone to necessary level.
Circuit description of microphone amplifier using 741
The entire circuit of microphone amplifier is build around operational amplifier 741. Op-amp 741 can be used in both inverting mode and non inverting mode according to necessary. Here we use 741 in inverting mode because at inverting mode input impedance is low.
A microphone is a transducer which changes sound energy into electric signal. Microphone detects sound and changes it into electric signal which is very weak and need amplification before given to loudspeaker. The output of microphone is given to pin 2 of IC1 through resistor R1 as shown in circuit diagram. The output is taken from pin 6 of IC1. The value of amplified output is equal to R1/R2 where value of resistance R1 is set according to impedance of microphone. Here we used resistor R4 as load resistor.
PARTS LIST OF MICROPHONE AMPLIFIER USING OPEARTIONAL AMPLIFIER 741
Resistor (all ¼-watt, ± 5% Carbon)
R1 – R3 = 1 KΩ
R4 – R6 = 10 KΩ
R7 = 1 Ω
VR1 = 470 KΩ
C1, C4 = 100 µF/12V
C2 = 220 nF
C3 = 100 nF
C5 = 3.9 pF
C6 = 220 nF
IC1 = LM 741
D1 = 1N4007