How to add OP amp 741 to LTSpice

Thread Starter

gtf0126

Joined Mar 29, 2023
3
Hello,
I need to use a uA741 op amp for my simulation but i cannot find it anywhere. I saw that many people use instead the LM741. Are they the same? What are the main differences? Anyway, I saw that a model for the uA741 was available in the TI site ( https://www.ti.com/product/UA741 ) but that model made the simulation impossible (i needed to simulate 5 seconds and it was capable to simulate just few micro second at a time, so it took an eternity to simulate...). In the same site i also found the model for the LM741 but it was in a completely different format and i was not able to actually use it. And finally, in a thread in this site ( https://forum.allaboutcircuits.com/threads/how-to-add-op-amp-741-to-lt-spice.139069/ ) I found tha another model for the LT741: the simulation time was ok but in a buffer configuration (output shortcircuited to the inverting input) it was not able to actually follow the voltage in the non inverting input correctly (maybe the op amp is just not suitable for this configuration?).
What should I do?
Thank you in advance!
 

Thread Starter

gtf0126

Joined Mar 29, 2023
3
Here you go. I cannot vouch for the model. It just happened to be in a library from @Bordodynov. His stuff is usually very good.
View attachment 291014
Just put all three files in the same folder and it should work. What you do after that is up to you.
Thanks! How can I add this model to my project? Simply copying the .lib in a folder and then adding the directive .include folderpath\filename.lib? Is there another way? What do i do with the file .asy?
 

Papabravo

Joined Feb 24, 2006
21,159
Thanks! How can I add this model to my project? Simply copying the .lib in a folder and then adding the directive .include folderpath\filename.lib? Is there another way? What do i do with the file .asy?
Copy the symbol and "opamp.lib" into a folder. When you place the component on the schematic in your project folder the symbol will automatically link to the companion library file (opamp.lib) in the same folder. This method is portable and avoids modifying the LTspice library. Some people consider this a good thing. Other people do not.
 
Last edited:

LowQCab

Joined Nov 6, 2012
4,026
All this is fine and good, as far as importing Device-Models, etc.
But a 741 is such a poor excuse for an Op-Amp,
why wouldn't You pick a more modern one ?
.
.
.
 

Audioguru again

Joined Oct 21, 2019
6,674
The 741 opamp is 54 years old. It is noisy, has a poor input and output voltage range so needs a fairly high supply voltage (most specs are with a +15V and -15V supply) and has such a poor slew rate that it has trouble above 9kHz.
Bury the old 741 opamp!
 

Bordodynov

Joined May 20, 2015
3,177
There are different circumstances. Because of the embargo I have to use the LM358, although it is also an old operational amplifier. Especially schools may have such microchips.
Besides, if the chip meets the necessary functions, then why not to use it.
 

LowQCab

Joined Nov 6, 2012
4,026
Because it's possible to pick 1-Family of Op-Amps that will have beyond
excellent performance in ~98% of the applications that You are likely to deal with.

The only time this may not apply is in a Mass-Production-Environment,
where cost is measured down to the 4th decimal place.
.
.
.
 

Audioguru again

Joined Oct 21, 2019
6,674
Will the crossover distortion produced by an old LM358 show in the 5 seconds waveform?
You can modify it by adding a class-A load to reduce the crossover distortion.
 

Bordodynov

Joined May 20, 2015
3,177
I used an LM358 in a Peltier driver. In my case it is not the sound passing through. I applied it because it is available at the local store. Although I would have preferred a different operational amplifier. But this one also serves its purpose.
 

Thread Starter

gtf0126

Joined Mar 29, 2023
3
The 741 opamp is 54 years old. It is noisy, has a poor input and output voltage range so needs a fairly high supply voltage (most specs are with a +15V and -15V supply) and has such a poor slew rate that it has trouble above 9kHz.
Bury the old 741 opamp!
What more modern alternative would you suggest?
 
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