Dual-Gain Microphone Audio Preamplifier

This is a very good hobby project and replaces the old microphone. A very good project for electronics beginner. This microphone is compact, sensitive and easy to use. It required DC bias voltage to work properly. See the below circuit to make the connections. You can also Subscribe to FINAL YEAR PROJECT'S by Email for more such projects and seminar.




In this project OP-Amp, the LM 741, is used. By now, if you have been building the previous projects, this one should be relatively easy. Gain is set by the ratio of the feedback to input resistors. There are two feedback resistors, each of which can be selected with a switch to give the desired gain.

A second switch selects or ignores the DC bias voltage, so the project can be used with either type of microphone. The usual coupling capacitors feed the input and output. A split DC bias supply voltage provides the correct bias to the non-inverting pin.


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