multisim 13 error?

[JJMC]

I am simulating a simple circuit.

One of my nets shows on the 4 channel oscilloscope the expected values: going from -20V on 71 us to +20V on 96 us.

The bahaviour of the circuit does not reflect this.

After searching I put multimeters on the same net.

On 71 us  this showed -17V and on 96 us -12V.

This looks to me a simulation error.

Note that after many simulation errors (stops) I had to put the parameters at

ABSTOL 1E-6 VNTOL 1E-3 RELTOL 1E-2 RSHUNT 1e*8 and max transient iterations at 500.

Thanks for any comments

[Chen_T]

Hi there,

Can you post your complete circuit? When I open it, it shows some files are missing.

My suggestions so far for your circuit is that try to replace all your GND as the normal symbol, because in some parts of your circuit you use the global connectors but some of them do not assign to Net 0.

Secondly, usually for simulation purpose, we use the inductors with the real values, try to replace all your rated_inductors.

Regard,

[JJMC]

Thank you.

I did what you advised and found my error (different from your comments).

I used the LM239 comparator out of spec: a -18V input with a +/- 15V supply.

It would be nice if the simulation would flag this instead of delivering inconsistent voltages on one and the same net.

Do you still want the source? If so,please let me know.

Jan

[ThiCop]

Hello Jan,

Please do share anything that is required to be able to reproduce the issue you're experiencing.

Once you have shared it I will also have a look at it to see where something is going wrong.

[JJMC]

Thank you Thierry,

The model is attached. I changed hierarchical blocks to subcircuits, I hope this makes sure it is complete.

A confidential part of the main circuit has been removed, but the error still shows up, also with the inputs of the LM293D now within spec.

In the first screenprint you see that net C1_active, attached to connector ON is 0V on oscilloscope XSC7, T2, and 10.233V on multimeter XMM1.

In the second screenprint it is 20V on XSC7, T1, and 10V on XMM1.

In case you look into it, please note that my other comment about a possible error in the model for LM293D (no open collector output) is also demonstrated in this model.

Kind Regards,

Jan

[JJMC]

For the sake of completeness, the attached screenprint shows the version etc.

Jan

[ThiCop]

Hello Jan,

After having a look at the schematic I have one remaining open question:

- Can you tell me what you specifically expect this circuit to do?
  I want to make sure I don't make any wrong assumptions.

  Or in other words what behavior/outputs do you expect/want during simulation?

Based on the schematic and the description it is not clear (to me) what you expect to see as the result of the simulation or what you are trying to simulate.

Before I know this information (and understand what you are trying to do) I cannot make any conclusions concerning (incorrect) behavior of certain components/models.

Thanks for providing this information!