problem with instruementation amplifier

[waqas5304]

hi
i am using INA163 as microphone amplifier for a 5 ohms symetrical microphone. when the mic is un plugged and power is on it give too much noise. i tried to place resistors at inputs with ground but of no use ., when i place a capacitor across the inputs the noise is gone . can anyone tell me the reason

 

[manish12]

mic and capacitor act as filter to the input !

if you remove it the input is float and generally amp has high input imp (Zin),

thats why it is act as noise source !

 

[FvM]

waqas5304,

please don't try to fool the forum. Your posting the topic a third time now, without answering the detailed questions that have been given in return. Probably you don't understand the technical background, that would be o. k.

I had been really motivated to help with the issue, but I'm tired of this now. I guess, other forum members could think similar.

If you are able to give the input circuit of your amplifier, including bias and supply voltage, I see a chance to find the solution. Otherwise, enjoy the noise. It can be agreeable, like listening to the waves...

Happy developing
Frank

 

[manish12]

ha ! ha ! ha ! .....................sorry !