I need a x18 amplifier to go from a sensor that provides 0-200mV and get 0-3.6V at the output. I have made the following circuit:
I have applied -1.5V with a battery between pins 4 (-1.5V) and 5 (0V). The circuit is supplied with 5V between pins 7 (5V) and 5 (0V). Between pins 2 and 3 I have applied 100.0 mV to adjust the resistance between pins 1 and 8 to the exact gain, but it has not amplify the signal. I have used different chips in case some disaster occurred when connecting it, but the same thing has happened with all of them. I've checked the diamond diagram and there doesn't seem to be anything abnormal:
After not finding the error and seeing that erratic voltages appear at the output (for example from 30mV to 40mV) I have tried to decouple pins 4 and 7 from ground, adding two separate 10uF capacitors, but the situation has not changed. Anyone ever happened something similar? Thank you.