voltage comparator

[siwahid]

Hello,

I'm trying simulate voltage comparator using Multisim 10. 

I use LM741 (as in "Circuit LM741.jpg"). The output is not limited to V+ or V-. Instead, it's going over kilovolt.

Why? Can you explain to me?

Then,  I replace LM741 with 741 op-amp. The result is as expected.

What is the difference between LM741 and 741 ?

Thx for helping .... 

[GarretF · Accepted solution]

The difference is most likely that the model you've selected for the LM741 does not model the power pins, and the output can exceed supply voltages for this simplified model. The only model for the 741 does model the power pins.

In the Select a Component dialog, there is a Model manuf./ID box, where you can select the model. for the LM741, which is made by National Semiconductor, I recommend you select the model with National as the manufacturer.

This behaviour has actually changed in recent releases. In version 10.1 and later, Multisim gives precedence to a manufacturer's model. You can also figure out how many pins are modeled by clicking the View Model... button (Model... in 10.0), and counting the number of pins on the .SUBCKT line. For example, in 10.0, for the component LM741AN/833, and model National/LM741_3, the .SUBCKT line is

.SUBCKT LM741_3       1   2  99  50  28

The numbers after LM741_3 are the names of the pins, of which there are 5. For the same component, but model IIT/LM741A, the .SUBCKT line is

 .SUBCKT LM741A 1 2 3

 so for this model, only 3 pins are modeled.

[siwahid]

Thank You!

It's have been solven by replacing model to LM741_3.