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Member
djb ecc
Posts: 3
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741 op amp ro error?

I built a simple 741 op-amp circuit so students could explore the output resistance and maximum output current for various op amps.  The circuit shows that the 741 can deliver more than 5 amps and therefore more than 25 watts.  I am brand new to multisim so I guess I must have something wrong with my circuit. I tried a number of different flavors of 741 but they all work the same in regards to output current.
 
thanks in advance
 
 
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lacy
Posts: 1,233
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Re: 741 op amp ro error?

I don't see anything wrong in your circut. According to the model information the op-amp in  your circuit is considered an EWB-4 3 terminal Op-amp. I have found these models to not be accurate. If you look in the parts database under where it says "Model manuf./ID" you will find there are more than one model for this op amp. Try selecting the ones that have a 2 or 3 as the last character i.e. ITT/LM741-2.

I believe these to be the most accurate. You can give it a try and see if this is more suitable to your purposes and whether it meets your expectations as far as the output you are looking for.

I hope this helps.

Kittmaster's Component Database
http://ni.kittmaster.com

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Member
djb ecc
Posts: 3
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Re: 741 op amp ro error?

Thank You very much Lacy.

I tried every 741, ( I got to get a life, lol) and you hit it right on the nose. The 2 and 3's work.  I will now always look for these op amp flavors and use them in my circuits.  As stated in my first post, I am new to multisim but have built thousands of circuits starting with EWB 2, 3, 4 and 5.  This forum is wonderful, and it's support might be the best feature of multisim.

Thanks again, and you have a great day!

dave

Active Participant
lacy
Posts: 1,233
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Re: 741 op amp ro error?

Thank you for your kind words about the forum. We try to help as best we can. If the users of Multisim (like myself) can't find a solution to your problem then one of the very helpful NI Support Staff members usually can.

I must caution you on one thing. I have found that not all op amps have more than one model. There are a few that only have one model and some of the time it is identical to the type that was giving you the problems. In that situation I usually try to find the manufaturer's model information, if it is available,edit it and save it to my user database. I thought I would pass this along to you so the next time you can avoid a potential problem and if you do encounter a problem you will have a way of getting around it.

 

 

Kittmaster's Component Database
http://ni.kittmaster.com

Have a Nice Day
Member
djb ecc
Posts: 3
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Re: 741 op amp ro error?

Lacy, your very welcome and thanks for second tip will try it when I become more familiar with multisim.

Thanks again