Why my Amp doesn't work?

[sanna]

why doesnt my amplifier work

HI,
I have connect my sensor to a bandpass filter and then to two linear amplifier after each other. It is strange that my amplifier doesn't work good. I have a gain of 360, but my signal after band pass is stronger than after amplifier?!
any one knows why?

 

[A.Anand Srinivasan]

please post your circuit... esp that of the amplifier and the configuration you are using...

 

[pfd001]

Does your amp work in close loop

 

[Areky_qin]

what's about you signals dc voltage level, and you amplifier's power? single or positive,negative power?do you set you signals at (P_power + N_power)/2,
and your signals swing range?

 

[Sadegh.j]

Hey

Your amplifier is obviously not working properly because:

- The input frequency does match the amplifier
- The amplifier design is not right
- your input saturates your amps

Cheers

 

[scintillatingstuffs]

Yes.. The main reason would be the saturation of your amplifiers.

 

[sanna]

Thanks for all reply, I will attach my circuit on Monday may be make it easier.
Thanks

 

[tvincent]

If you are using two (2) opamps in a sensor circuit the first stage should be a lower gain. You may start with about (10), then the second stage can make up the difference. Try it and see if that works. Also calculat the total gain, use the second stage to provide the gain you are looking for. If you are interfacing to a microcontroller to an A/D the like to see a low impedance. About 1-2K ohms. This is for the charging capacitor in the A/D. Hope this helps.

 

[qutang]

u can post your circuit on