shibas

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.

Iam using a vibration analyzer or sensor.I need to amplify the above sensor's output signal.For this purpose i used opamp ic 741 in the non inverting configuration.But when i gave the input to the amplifier from a function generator the amplifier gave a gain of about 50 and 68 initially.When i changed the input frequency from the function generation to 1 khz amplifier gave a gain of 100 even though the amplifier circuit was originally designed to give a gain of about 101. But for my application,when i give the input to the amplifier from the output of the vibration analyzer the gain of the amplifier circuit changes to a huge value of about 450. What may be the reason for this? At first i used AD620 ic for the amplification instead of the op-amp ic 741.The behaviour of the gain at that time was also similar to now. Somebody please help and reply fast.