op-amp current sensing problem

mshh · Mar 9, 2014

i tested the attached circuit again but i forgot to connect pin3 ( red circle ) the chip got hot and burnt up for the second time . i don't know why . also i measured the signal on zero ohm resistor it was 8.3 mv the output was .83 volt which mean that the gain is 101 not 51 however gain=1+1000/20 = 51 , i also tried another resistor and i got the same results the output multiplied by 2 ,i tried lm358 and it give the same results.

chuckey · Mar 10, 2014

With R4 being .006 ohms every bit of wire in the current monitoring circuit will drop some voltage, is R7 returned to exactly the end of R4?
Frank

mshh · Mar 10, 2014

chuckey said:
With R4 being .006 ohms every bit of wire in the current monitoring circuit will drop some voltage, is R7 returned to exactly the end of R4?
Frank

yes , i made all the resistors closed as possible as i can .gain isn't correct

op-amp current sensing problem

mshh

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op-amp current sensing problem

mshh

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