my circuit goes convergence error and it is not simulating

[roel1234]

hi!!!
im simulating this circuit...
then it just went to convergence error!!
and i alow it to solve it but it only consumes time and it cant fix the problem!!
the error came when i reset the display circuit!!!
can someone help me with this matter??
 by the way im using circuit design suite 10.0.1!!
gud day!!

[lacy]

The reason your getting this message is because you have you maximum timestep in the simulator settings is way too low. Try setting it to .0001.

Also, you need to ground the second timer.

There is one other problem and that is with the first timer. This has no bearing on the error message, but you have the duty cycle of the first timer set below 50% and in it's current configuration would not work in reality. Your R9 should alway be lower in value than your R10. The way to achieve less than 50% with a timer is to place a diode across R10 and recalcualte your resistor values.

I mhope this helps. Let me Know if you encounter any other errors.

[roel1234]

oh thanks!!!  i will change that!!
thanks again!!!
have a nice day!!!

[roel1234]

Hi Lacy.
I did some changes in the circuit to fit my requirements.
So the result is vr2 of the circuit. i also included the ultiboard.
So here are my questions.... this a lot of questions!!!

1. I change the simulation settings the way you said., but the simulation is way to slow and the simulation error occured at 7.836 seconds. in Addition to that the convergence assistance can't reproduce the error( as always hapens to me). Is there any settings that can simulate the circuit faster like in real time without resulting to convergence error?
2. what does drc do in multisim? Could that be the source of the conergence error?? how can i fix it? all it does is creat a red circle in some connection!!
3. I transfer this circuit to ultiboard, and the Drc tab turns red saying Pin "7" from Component "U2"(74LS290D) in Net "0" is missing from shape "DIP14300" etc. What does that mean? what should i do to fix this error? could this be a source of conergence error?
4. another ultiboard question. is ther a setting that only allows surfacemount parts to be solder on copper top? because it is hard to solder a DIP parts in copper top (im a kinda manual person!!!) specially when using ic sockets.
5. And lastly im exploring the ultiboard. I saw that if im going to print a copper top or bottom of a pcb, the preview is always to big or to small... what setting should i play with so that if i want a 3inch by 2inch board it will print an exact size and its component accurately??? no more no less just exact!!! before i waste ink and paper!!!

Im sorry to disturb you in this season!!!
Marry Xmass and a Happy New Year!!!

[lacy]

O.K. I am going to tackle these as I get a solution for you or an explaination compiled.

1. I did manage to get the circuit simulating for the full time without convergence error. What I did was to take all the Analog components off of VCC and run them to the analog DC Power. I have found on a number of occassions that it is best to separate the analog components from the digital power sources and run them to their own DC Power Source to prevent problems when simulating. For some reason when you hook analog and digital components together on the schematic the simulator likes for each to be coupled to its appropriate power source otherwise it starts coughing up errors. As far as real time is concerned that is not possible with Multisim. You can get close, but you run the risk of timestep too small errors. It takes the simulator time to number crunch and it can't do that very fast. The larger the circuit the more real time it takes to simulate. On very large circuits it may take 1 minute of "real time" to simulate 1 second of circuit time. Basically it is the nature of the beast and there are very limitied options available to speed it up without it spitting errors at you. I will post the updated circuit for you to try.

2. DRC errors do not effect simulation. They are user adjustable and only there to advise you that, according to your settings, you have a wire connected where you didn't want it connected i.e DC voltage on a timer output. You can turn these on or off by going to TOOLS>ELECTRICAL RULES CHECK>ERC RULES and disbling the ones you want by turning them from red to green by clicking on the square.

[lacy]

3. The transfer error was caused by their being 2 instances of Refdes U2 in the circuit. How this happened I do not know, but you need to change the 7404 designation from U2 e to another number and then it will transfer properly.

4. I am not exactly sure what your requestring here, but it sounds to me like everyhting is routing on the top layer. This can be dealt with in two ways. One way is to lock the PCB setting within Multisim. This only works if you have the full spread sheet at the bottom avaialble to you. Goto the Nets tab and scroll tio the right until you see LOCK PCB SETTINGS. click on it to highlight all nets and then select one net and change it from yes to no and it will change all of them at the same time. The other way is to do the same procedure in Ultiboard. Goto Nets>Routing layers and select all the nets by using CTRL>Left mouse button and then change just one of them to change them all. This second method will also allow you to change just certain parts to be routed on certain layers. You have to change the numbers to reflect which side to route them on. 10=Top 01=Bottom 11=Both sides. This technique works with the Power Pro Edition with the full spreadsheet. If your version is different then the only technique I know of that can get you routes where you want them is to edit them in the Net List Editor within Ultiboard

[lacy]

5. This would have to be done in your printer set-up at the top right of the print dialog box. I have tried to set my printer to 3in X 2in, but it won't let me go no lower than 3in X 5in. This would work. but it is still going to use a whole sheet of paper if you are using a 8.5 X 11 inch sheet to print it on uless you print one side and cut it out and then re-use the same sheet to print the other side. This is the only option I can see on this.

[roel1234]

1.thanks for the edited version of my circuit!!
2. it sims that drc has nothing to do with covergence error! thanks for the explanation regarding drc.

[roel1234]

3. so i must change the number.
4. now i got it. its like a binary number that allows top, bottom or  either both  of layers. by the way im using power pro edition.

[roel1234]

5. it does not matter if it is using the whole paper my friend. as long as the shape and distance of every component is exact. because the preview is not accurate. it is in percent. i wonder what would be the setting to achieve this kind of output?