*Very* New User! -- Two Simple Questions

[diode]

I am self-study, with no one to talk to but myself; and am in the middle of the 30-day evaluation period of the MS v10 Student Edition. I have two questions, please: 1) Is there an official MS product tutorial somewhere? (All I have been able to find so far are two informal university starter documents, from Google searches.) 2) Can someone please explain to me why MS does not consider the two simple circuit diagrams in the attached MS file the same? (The top one is clearly not simulating correctly.) Thank you very much for any assistance

[diode]

Well, I guess it's clear that I'm a very new user. I couldn't even get the attachment to stick. Sorry. Here's another attempt...

[Lodin]

Hello diode,

very nice problem.

The above circuit looks correct, but it is not correctly drawn !

Mark the small (connection) dots below R2 and R3 and drag them 3 grid steps to the right and you will see, how this circuit is really connected. 

This "new" circuit is simulated correctly.

regards, Lodin

[diode]

Hello Lodin, Your English is just fine -- better than mine! I have made the changes as you recommended, and I agree that it appears to simulate correctly. So what I now do not understand is why my original did not -- i.e., what was incorrect about my original schematic? And doesn't the original schematic seem a bit "cleaner" than the new one? (see attachment, if I can get it to work this time.) I am not at all being critical, I'm only trying to understand the workings of this program... Thank you again, very much

[Lodin]

Hello diode,

the problem is, that what you see as a drawing is not allways that "infomation", that is in the simulater.  Sometimes the "autowiring" of Multisim produces "strange" results. The simulator does not "see" the drawing, it only "see" the circuit as it is in the database.

If you see "connection dots" at wrong positions or misssing, this should be a warning to you. It is possible, that the data that represents your circuit inside the database is different from what you see as a drawing.

Its allways a good idea to "clean" your drawing to a perfect, nice looking one. You must be very critical and precise(?) to get correct results. The original circuit was not cleaner, there were "connection dots" at wrong positions (R2 , R3) or missing (ground line).

regards, Lodin

[Lodin]

where is my attachment now ?

[diode]

Thank you so much, Lodin!

I now understand what's going on from your first two paragraphs. I've had similar quite frustrating difficulties before, and this now helps me to come to grips with those.

Re your third paragraph, I think my problem is that I do not understand the rules that govern the behavior and management of the little red connection dots. From your attachment, I can certainly see the difference between the two diagrams, and yours clearly simulates correctly. But I also see lots of places where my intuition tells me that there should be little red dots -- and there aren't any.

I'm sure the conventions are straightforward, and the rules are consistent, but I just don't know what they are. I guess you can see why I could sure use a basic tutorial!

If you or anyone knows of one, I would be most grateful for that advice. Otherwise, you have been most helpful; and I will continue on with my trial and error journey...

Best regards,
diode

[lacy]

On the first question. When you installed Multisim there should have been a users manual in the documentations folder. I have not downloaded the evaluation version so I am not quite sure what is included with it, but you might want to check and see if there is a documentation folder. I will see if I can find another source for this in case the manuals weren't included in the download.

On the second question I actually have an answer. In the top circuit for both files, the resistors in the parallel portion somehow did not get connected to ground. I am not sure how this happened. What you need to do remove the probes, delete all the wires coming from the bottom of the resistors and re-run them to ground. Then place your probes on the wires. This will correct the simulations results to what the bottom circuit is showing.

I hope this helps.

[lacy]

This may help you in your thinking about the red dots (junctions). If you run your wires between components Multisim will atutomatically place them where they are necessary. So you really don't have to worry about placing them as the program does this for you.

Maybe that will help in your understanding of these.

[diode]

Thank you for your replies, Lacy.

You are indeed correct! A thorough search of my machine found a "Getting Started with...", and a "User's Guide". I haven't found a tutorial yet, but hopefully these will suffice. At the least, there appears to be many pages that I need to examine before I trouble this discussion group again.

Regarding the little red connection dots, I've done a lot of experimenting since your, and Lodin's, last posts. I still don't know why my original connections didn't; but I believe that I now see how to make them work correctly in the future.

Thank you both, again, for having the patience to help out a struggling new user!!!

Best regards,
~~diode