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I come here to get help from the experts.
I am using this BJT transistor in the circuit.
2N3904 - Central Semiconductor Corp - Transistors (BJT) - Single - Kynix Semiconductor Hong Kong Limited.
Here is the microphone that I am hooking up in the circuit.
It's an electret condenser microphone from kynix.
http://www.cui.com/product/resource/cma-4544pf-w.pdf
Here is my design
i am powering the circuit directly from 5v arduino pins.
I am following the tutorial from this link to build the amplifier. It's exactly the same circuit but with different values to make it work with microcontroller. For that, I have used the supply voltage of 5V instead of 9V as in the tutorial. I have also tweaked the values of resistors to make the correct biased voltage.
http://www.youtube.com/watch?v=Br3uOM0IVjc

The problem is that I get a lot of noise. I checked with oscillosope and it is biased correctly, i.e., midway between the 5V. But you can see a very noisy signal. I hooked the circuit to a computer speaker and you can hear the noise after you hook up the circuit. The output works correctly though, i.e, when you play a sound in the microphone you can hear clearly in the speaker but during idle there is a noise that is audible.
What is the reason of this noise and how to minimize it while the microphone is sitting idle?
I am thinking will the noise coming from any of the components in the circuit ? That's my hypothesis .If it was wrong, please ignore it. Thank you for the help.
Thanks in advance! I really appreciate any help!
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