Multisim and Ultiboard

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ideal op amp

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multisim project1.jpg

Above is a circuit I was given and the only instructions given is this:


Use Multisim to solve following problems. Use multimeters to display required outputs for given circuits.

  1. Find iL (in microamperes)  in the circuit in following figure. 

Can anyone help? I am at a total loss and have been tought NOTHING about using multisim... below is the circuit I have constructed.


project3_1 - Multisim - [project3_1 _]_2013-12-05_15-14-30.png


I can't help but feel like this is wrong, I picked a random op amp from the giant list of them... the instructions don't specify which to use.  But I will say this, everything we have done on paper we are to assume it is an ideal op amp.  Some one please help if you can, I am quite confused at this point...

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Message 1 of 5

For that circuit almost any op amp is very close to ideal.


You can use a voltage controlled voltage source as an ideal op amp.


Your real issue is that you have shorted the output with your ammeter. An ammeter needs to be in series with the element carrying the current you are measuring.



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Message 2 of 5

Thanks for the reply, but I still have issues in that using diffrent op amps give me drastically diffrent results.

As for reading the current, I believe I have fixed that (below), thanks


project3_1 - Multisim - [project3_1 _]_2013-12-05_21-51-35.png.


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Message 3 of 5
Accepted by topic author KyleRTTU

The AD827 is probably not a particularly good choice for such a circuit as it is intended as a video driver for applications with MHz bandwidths, but it should work.


That is the correct connection for the ammeter.


It is difficult to tell from the image but it appears that you have the power supplies reversed.  According to Analog Devices datasheet the Q package has V+ on pin 8 and V- on pin 4.



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Message 4 of 5

Thanks for the help, I ended up using a virtual op amp, and it seems to work.

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