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Active microphone preamplifier using LF356

This is an active microphone preamplifier circuit for the particular condenser microphone. Generally, the condenser microphone has high sensitivity and the high output signal more than the other types of microphone, but this type needs to have a power supply.

How it works

Figure 1 is a circuit diagram of this project. The condenser microphone M1 need to has a power supply from the current flow through R1 to it that has 2 lead. Its signal will be coupling through C1, R3 to the IC1’s pin 2.

Active microphone preamplifier using LF356


Figure 1 the circuit diagram of this project.

The gain of a circuit will be is determined by R5/R3, this gain is 10 times. The capacitor C2 will offset circuit working to lower the gain when high frequency.

The output at the IC1’s pin 6 will be sent to C4, R6 to other section as we need.

This R2, R4, and C3 are connected together for bias to IC1. So, we can easily use a generally single DC power supply(positive and negative polarity).


The part you need

IC1: LF356 JFET Input Operational Amplifiers (or LF155/LF156/LF256/LF257/LF355/LF356/LF357)

0.25W Resistors, tolerance: 5%
R1: 10K
R2, R4: 1M
R3: 15K
R5: 150K
R6: 330 ohms

Ceramic Capacitors
C1: 0.01uF 50V
C2: 0.001uF 50V

Electrolytic Capacitors
C3: 1uF 50V
C4: 10uF 16V
C5: 47uF 16V

How to builds

the copper layout and component layout
Figure 2 the copper layout and component layout.
This project is smallest so can use the perforated PC board or universal PCB Board and you can build PCB as Figure 2 actual-size of Single-sided Copper PCB layout and components layout.

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