Capture and current-dependent current source

Thread Starter

ondiola

Joined Jan 12, 2018
4
Hello, I'm trying to simulate the following circuit:

using Orcad Capture CIS. I have a problem with that current-dependent current source. May I ask you how to connect that CCCS to the rest of the circuit?


I suppose I have to connect the first of two inputs of the CCCS to the node A. But what about the second input of the CCCS? How to connect it?
Thanks in advance :)
 

WBahn

Joined Mar 31, 2012
29,976
You need the current Io to go through the control side of the CCCS the same way that you would use an ammeter. So you need to break the wire coming out of the positive terminal of V1, send it into the TAIL of the current arrow on the CCCS, and then send the current coming out of the HEAD of the current arrow back to the other side of the break you made.
 

WBahn

Joined Mar 31, 2012
29,976
You didn't do what I said. You need to BREAK the wire coming out of the top of V1.

Imagine you are the current coming out of the battery. There must exist one and only one path taking you from the top of the battery to the right hand side of R3. That path must go from the top of the battery to the tail of the arrow on the CCCS, through the arrow, out the head of that arrow and then on to the right side of R3. There can be NO junctions along the way. NONE.
 

crutschow

Joined Mar 14, 2008
34,280
When you are given a change to the circuit, you need to check if it makes sense, not just blindly make the change, and then wonder why it doesn't work.
 

Thread Starter

ondiola

Joined Jan 12, 2018
4
Thank you very much for explanations and suggestions (and for patience too). Now Capture is showing the correct results. I'm not a good english speaker, so I usually understand 90% of what is being said... And that 10% always brings problems!

It may be helpful to post the correct scheme, maybe someone else is going to have the same doubt:

 

WBahn

Joined Mar 31, 2012
29,976
That's got it. Note that you can play with that schematic to get it so that no wires cross, but the way you have it now is a much closer match, visually, to the original circuit. Both can be argued as being the better route.

But at the very least I would flip the CCCS over so that it is on the right of the branch it is in. That will make things quite a bit cleaner all by itself.

Clean, well laid out schematics are a HUGE benefit and it is worth taking the time and getting in the habit of always putting in the effort.
 

WBahn

Joined Mar 31, 2012
29,976
Thank you very much for explanations and suggestions (and for patience too). Now Capture is showing the correct results. I'm not a good english speaker, so I usually understand 90% of what is being said... And that 10% always brings problems!
Understood.

And as frustrating as it is, rest assured that your ability to speak English is far, far superior to my ability to speak your native tongue, regardless of what that might be.
 

MrAl

Joined Jun 17, 2014
11,388
Thank you very much for explanations and suggestions (and for patience too). Now Capture is showing the correct results. I'm not a good english speaker, so I usually understand 90% of what is being said... And that 10% always brings problems!

It may be helpful to post the correct scheme, maybe someone else is going to have the same doubt:

Hi,

That looks right now. If you post some voltage/current results we can compare notes too.
 
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