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MIC Pre-amplifier
- Rajkumar Sharma
- 34.987 Views
- moderate
- Tested
- SKU: EL34240
- Quote Now
- 0 Likes
This project is a microphone pre-amplifier based on LM358.
Description
This is an easy to construct microphone pre-amplifier project using a compact electret condenser microphone. The pre-amplifier is the important building block of many audio communication systems. The circuit has been built around Op-Amp LM358.
- Power supply : 5 to 12 VDC @ 10 mA
- Output: Gain Approx. 100
- On-Board electret condenser microphone
- Header connector for connecting of power supply input and audio output
- Power-On LED indicator
- Four mounting holes of 3.2 mm each
- PCB dimensions 35 mm x 40 mm
Schematic
Parts List
Gerber View
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PCB
thanks for this
Could I replace the mic you used with an XLR input? Trying to figure out how to make an adjustable XLR preamp for cameras.
The mic output is in the range of mV and needs a bias resistor R2 in order to work. In addition you can feed a small signal like that directly on C3 and omit R2 resistor so you get an amplified signal on the output.
LM358 is not a low noise IC, Use of TLO71 / TLO81 would give better low noise response, cheap and easily available.
The foil side of the PCB image has to be mirrored. In that case your logo and the “800A” would be backwards.
I’ve uploaded PCB in PDF file in the downloads above. Thanks
Hello, I have given the same circuit in the bread board, & i have given input from my phone with the help of 3.5 mm audio jack…..but i couldn’t hear the output through earphones or audio jack. I can guess some processing is happening. The earphones are working properly,and i couldn’t find out where the problem is…..please help.
Could you explain a little more about your setup. Have you removed the mic and R2 bias resistor? I would suggest to start a new topic on forum. This is the best place to discuss your project. https://www.electronics-lab.com/community/