ad 620 instrumentation amplifier

[shibas]

For amplifying Vibration sensor output.

I am posting the circuit diagrams of both the amplifiers:-

1.circuit of AD 620 instrumentation amplifier,designed for getting a gain of about 106.

2.circuit of non inverting amplifier using op amp ic 741,designed for getting a gain of about 101.

The gain equations of both the amplifiers are written inside a box near both the circuit diagrams iam attaching with this post.

I tried both the above amplifiers for amplifying the output of a vibration sensor or analyzer.

But when i gave the input from the function generator both the circuits amplified well.

For the non inverting amplifier using 741 ic,when i gave the input from the function generator at first i was getting a gain of about 50 and 68 when the input signal frequency was about 9.7 KHz.When i changed the input signal frequency to about 1 KHz i got the gain of about 100.But the original gain designed for this amplifier circuit was 101.When i gave the sensor output signal to the input of the non inverting amplifier it gave a gain of about 450.


When i used AD620 amplifier circuit,I get a gain value of about 100 when i was giving input signal from the function generator.When i gave the output signal from the vibration sensor as the input to the AD620 amplifier it also gave about a gain of about 450.

Why is the gain becoming very high when i give the sensor output as the input to the amplifier?

Which amplifier should i use for my need(for amplifying the sensor output)?

Should i make any modifications to my circuit.If then please suggest those modifications clearly.

Somebody please help me and reply fast.

 

[KrisBlueNZ]

But when i gave the input from the function generator both the circuits amplified well.

So it's OK with a function generator but not with the "vibration analyzer or sensor"? What can you tell us about this analyzer/sensor? That description by itself doesn't tell us much. Do you have a manufacturer, part number? Link to a data sheet? List of basic specifications? What is it monitoring the vibration of?

How are you measuring the input and output signal levels?

Have you tried an op-amp with a higher gain-bandwidth product (GBP)?

Speaking for myself only, I'm about to give up trying to help you, because you have been asked so many questions but you have given so little information in reply. We can't operate "in the dark"!

TRY to answer ALL of the questions in this post.

It would also help if you would go back and read ALL the previous posts in this thread and (at least) TRY to answer ALL of the questions in them as well.

We are all happy to try to help, but you HAVE to provide more information.

We are not standing next to you; we can't see everything you can see.

We don't know what you've tried. We don't know how you are making your measurements. We don't know how you have done your tests. YOU need to TELL US.