LOW NOISE op amp

[padmow]

Hi,

I wonder if there is any suggestion about which op amp I can use which
has Low Noise, and only need 9V from battery.

This is for amplifiying signal from electret microphone. The opamp
would then drive class AB transistor amplifier.

Thank you

Padmow

 

[padmow]

You are very detail about explaining it. Thank you very much.

I hope you don't mind, how do I measure the "output impedance" of the
electret microphone.

Also how to choose the suitable resistor which connected to +, the
positive voltage suply.

About the LT1677, why it is not the best for the design.

Again Thank you very much
Padmow

 

[padmow]

Thanks again.

I did try to use LM 386 before but it wasn't that successfull.

the microphone was couple with capacitor to LM386 , while LM386 drive
loudspeaker directly. The voice is weak, even I increase the LM386 gain
, its still weak.

Any idea about this.

Thanks
Padmow