Multisim and Ultiboard

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answer is not the expected.

Hi, i made the simulation of this circuit and the response of the circuit is not the expected based on the signal obtained from a real oscilloscope. I'd like to know whats the problem. The frecuency just before the first inverter is a lot bigger than the frecuecy after the second opamp and it is not seen in the real circuit.
Thanks
 
 
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Message 1 of 15
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I think I found your problems.

1. U4B doesn't seem to be connected. The grounds on the o-scope are not connected.

2. This is the real solution. Goto the Simulate Menu. Under Digital Simulation Settings. In the dialog box check the circle for Real.

3 Make sure you place VCC and a DGND connection somewhere on the schematic. I usually like to place VCC, VDD, VSS and  DGND just to make sure I cover all the bases when it comes to digital components. These don't have to be connected to anything, but just have to be there when you use the Real Setting for Digial Simulation Setting.

I hope this gets you the result you were looking for. Have a Nice Day

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http://ni.kittmaster.com

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Message 2 of 15
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I just re-simulated and I have to make a correction. Do not put VSS on the schematic. Just VCC and VDD and DGND. VSS makes it go back to what it was doing the first time.
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Message 3 of 15
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Lacy's diagnostic is correct, half the circuit is disconnected and the scope is not hooked up properly.

I did the same and it seems to develop a startup ramp and square wave as it should.


Signature: Looking for a footprint, component, model? Might be here > http://ni.kittmaster.com
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Message 4 of 15
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Could you please send the modified file? Thanks
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Message 5 of 15
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Sure no problem:

 

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http://ni.kittmaster.com

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Message 6 of 15
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Hi... having problems again.... when i simulate the circuit everithing is well but i pasted it into another project as a subcircuit and it doesn't work...

Please help

Thanks

 

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Message 7 of 15
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just before i added the mxrhot_box to the project everithing was working well... so i think the problem is in that subcircuit.
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Message 8 of 15
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Goto the Simulation Tab. Goto to Digital Simulation Settings and click on the dot in front of Real. This should get it working. Just so you will know it seems to me that there are a lot of the digital components that do not work when the Digital Simulation Settings are set to Ideal. Most of the time I find they will only function correctly when it is set to Real. This may be something that NI needs to look at.
 
Hope this helps.
 
Have a Nice Day.
Kittmaster's Component Database
http://ni.kittmaster.com

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Message 9 of 15
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Hi, i already modify the simulation settings... but it is still not working... It seems to be the inverter in the mxrthot_box, look at this and tell me what do you think... I modified the values of the vss source of that subcircuit but it affected all the others subcircuits so i modified the vss source in the 4009 (Switch subcircuit) and i called vss2 and it worked fine. Look at the 4009 in the mxrhot_box which is the one i think is not working.

Thanks

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Message 10 of 15
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