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Message ID: 12369     Entry time: Wed Aug 3 18:53:46 2016
Author: Praful 
Type: Update 
Category: Electronics 
Subject: Mic Amplifier 

I could not get Den's circuit to work for some reason with microphone input, so I decided to try to use another circuit I found online. I made some modifications to this circuit and made a schematic:

Using this circuit, I have been able to amplify microphone input and adjust my passband. Currently, this circuit has a high-pass at about 7 Hz and a low-pass at about 23 kHz. I tested the microphone using Audacity, an audio testing program. I produced various sine waves at different frequencies using this program and confirmed that my passband was working as intended. I also used a function generator to ensure that the gain fell off at the cutoff frequencies. Finally, I measured the frequency response of my amplifier circuit:

ampTest_03-08-2016_180448.pdf

A text file with the parameters of my frequency response and the raw data is attached as well.

These results are encouraging but I wanted to get some feedback on this new circuit before continuing. This circuit seems to do everything that Den's circuit did but in this case I have a better understanding of the functions of the circuit elements and it is slightly simpler.

Attachment 2: ampTest_03-08-2016_180448.pdf  18 kB  | Hide | Hide all | Show all
ampTest_03-08-2016_180448.pdf
Attachment 3: ampTest_03-08-2016_180448.txt  43 kB  | Show | Hide all | Show all
Attachment 4: simple_amp.png  23 kB  Uploaded Wed Aug 3 19:57:25 2016  | Show | Hide all | Show all
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