08-01-2008 05:27 AM
08-01-2008 05:48 AM
08-01-2008 07:17 PM
First circuit solved. The CMOS gates you have there require the power source VSS to on the schematic somewhere. What you need to do is to examine the components pin requirements under Properties. This may save a lot of headaches when placing/hooking them up. I think the hidden pins need to have something done about them as it seems to me to becoming problematic when placing them. If you don't know to look in the Properties menu under pins to determine their voltage requirements then thing like this are bound to happen.
Hope this helps. Looking at the other circuit now.
08-01-2008 07:29 PM
08-01-2008 07:39 PM - edited 08-01-2008 07:42 PM
O.K. Second circuit. I did manage to get it to simulate, but not the way you would want. What I did was to replace all the anolg ground to the DGND and added the VSS. This got it simulating with only one output pulse.
Now the bad news. Since I can rememberI have not been able to get CMOS Oscillators to work, period. This goes back to at least Version 2001. There may be a way to get them working but I haven't found it.
If NI has an answer for this I, for one, would like to know what it is.
08-01-2008 09:30 PM
08-01-2008 09:53 PM
08-01-2008 10:10 PM
08-01-2008 10:50 PM
08-02-2008 09:03 AM
Here's the reason why your PLL worked and this particular set of circuits won't. In the PLL you had the digital simulation setting set to IDEAL. You don't need to have the power sources on the schematic under these circumstances. Also you are clocking the 4011 IC's with a 4013 Flip Flop that is tied to a clock source. In the PLL circuit you are not trying to get it to self-oscillate. Even the VCO is a not made up of these CMOS IC's rather a Voltage controlled square wave oscillator.
One other thing. I told you about the connector in your board tester numerous times and apparently I either didn't make what I was saying clear or you just didn't grasp it at the time.
CMOS Oscillators will not work in Multisim. It is hard to even get a regular oscillator using discreet components to work. Maybe you can find something that I am missing here, but I have tried a number of CMOS oscillators from books and from the web and they just do not function. I was trying once to design a model for an IC that used an internal CMOS oscillator. I could get the rest of the circuit working using an external clock frequency, but I never could get the on-board CMOS Oscillator to work and without that the chip would have been useless. So I finally said screw it and gave up on the project.
I really hope you can get these to work. I would encourage you to keep trying and not give up like I did. Who knows, maybe you will be the one to finally figure it out.