op-amp current sensing problem

[mah]

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.

 

[ronsimpson]

I don't know why.
Maybe you have 8 and 4 mixed up in the wiring. That will burn up the IC.

 

[mah]

I don't know why.
Maybe you have 8 and 4 mixed up in the wiring. That will burn up the IC.

no it is not , because it was working when this wire was connected
but the ground of supply +5 v of the op amp was connected to pin3 instead of ground , could that be the reason as i read in datasheet its analog input Vss-0.3 max . could that wiring applied -5v on the input ?

 

[crutschow]

The circuit you posted has a gain of 12,001.

How can you measure any voltage across a "zero ohm resistor".

 

[mah]

sorry it was drawing mistake i edited it please see it again

 

[KeepItSimpleStupid]

See this thread: https://www.electro-tech-online.com/threads/need-help-wiring-a-load-fault-indicator.140198/