hello,

I want to sense the current in an h-bridge module , I used op-07 because it has low offset voltage , I tested it on a breadboard in the non-inverting dc gain configuration with a potentiometer on the input and it worked fine.

when I install it in the circuit , the output is always slightly less than Vcc , (14v with Vcc=15 , 16.5V with Vcc=18) , this is the circuit schematic , is there something wrong with it?

opo7 datasheet : http://www.ti.com/lit/ds/symlink/op07c.pdf

 

You mention Vcc. What is the op amp negative supply pin connected to?

 

vcc- (pin 4) is connected to ground , but pins 1,8 are not connected (and i don't know what offset n1 and offset n2 mean)

 

Look at the datasheet page 5, shows how to connect the offset null pins, these are used to make the output Zero at different input levels.

Again if you READ the datasheet you will notice the maximum output is +/- 13Volts @ >10K load (page 4)

 

vcc- (pin 4) is connected to ground

But the OP-07 opamp has inputs that MUST be at least 2V more positive than its vcc- (pin4). The circuit will work properly if you add a negative supply voltage to pin 4. I don`t know why your breadboard circuit worked.

 

Look at the datasheet page 5, shows how to connect the offset null pins, these are used to make the output Zero at different input levels.

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The null pins are to make the output zero, with zero input voltage, not to offset it for different input voltages. To do that properly you need to add an external input voltage of the appropriate polarity.