3 input microphone preamplifier
Decription.
The circuit given here is of a three input mic mixer cum preamplifier using the IC LM348. The LM348 is a high gain, internally compensated quad operational amplifier with a class AB output stage. The IC has very low input supply current drain (0.6mA/ opamp) and operates from a dual power supply.
Out of the four op-amps inside the IC LM348, IC1a, IC1b and IC1c are wired as non inverting amplifiers and they serve as the input amplifiers for the corresponding mic channels. The output of these three amplifiers are tied together and connected to the inverting input of the IC1a which is wired as an inverting amplifier. IC1a mixes the signals from each channel and also works as the output stage.
Circuit diagram.
Notes.
- Assemble the circuit on a good quality PCB.
- Use +12/-12V DC dual supply for powering the circuit.
- The power supply must be well regulated and filtered.
- POT R5 to R7 can b e used for adjusting the gain of individual channels.
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Hi Emmi approximately 100 ( 101 1 + Rf / Ri ) First stage gain is 101 and second stage gain is 1.
Input and out put will be out of phase by 180 deg.
what is the total gain of this pre amp
I am pleased to get all the Electronic Circuits and the Communication Circuits ,I Need Following Lab.Manuals & Lab.Sheets for my Electronics Lab.1,at Riphah International University.I/14 Golra More,Islamabad Pakistan.
(1) Electronic Circuits. (2) Electronic Devices (3)Linear Integrated Circuits (4) Network Analysis (5) Linear Circuit Analysis.
Kindly if you can provide.
Hoping a favourable Reply.
Engineer Abdul Rashid.Electronic Lab-1,Email:- rashidadbul@yahoo.com, Mobile No;- 0300-5048640. Office 92-051-5469641-6, Ext 240