LTSpice, Some Basic Questions

[aljamri]

Hi,

As a beginner, I've started this thread to put whatever I face of questions in LTSpice. For someone it may seem basic, but for me it will take me step ahead.

For now, here are two questions:

1- for the attached schematic, how to measure voltage across the transistor E and C (VCE)?

2- What does .tran 0 10 0 1 means?


Thanks

 

[ericgibbs]

Hi,

As a beginner, I've started this thread to put whatever I face of questions in LTSpice. For someone it may seem basic, but for me it will take me step ahead.

For now, here are two questions:

1- for the attached schematic, how to measure voltage across the transistor E and C (VCE)?

2- What does .tran 0 10 0 1 means?

Thanks

hi aljamri
To measure Vce, plot Vc ,as Ve is 0V reference potential

.tran 0,1 .2 1u
1....means run the Sim calculations for 1second time [ not real time as seen by the user]
.2 start to plot the data 0.2second after the Sim run starts
1u is the maximum time step for the calculations, I usually leave this blank, let LTS decide.

OK.?
BTW: your .tran means run the calcs for 10s time and start the plot 0 seconds later, with a cal interval of 1second.... not going to happen

EDIT:
Its always a big help if you post your asc file, when asking a question.

 

[aljamri]

Thanks Eric,

To measure Vce, plot Vc ,as Ve is 0V reference potential

Tried to make Ve as 0V reference but I don't know if this correct ( Attached )?

 

[ericgibbs]

Thanks Eric,



Tried to make Ve as 0V reference but I don't know if this correct ( Attached )?

hi,
The grounding symbol automatically sets the ground 0V reference, so the BLACK test probe is not required.

When you press RUN, place the RED probe on the collector and you should see a plot.

With that .tran setting nothing is going work, please post the asc file and I will edit it for you.

EDIT:
Look at this image

 

[aljamri]

Sorry for being late but this is my office timing.

here are all the files, although I prefer to lead me doing correction my self to double the benefit

 

[ericgibbs]

Your asc file works OK for me.
What problem do you see.??

 

[aljamri]

To make it clearer, I've plot the attached circuit, I want to measure the voltage across R2 which suppose to be 10v only.

 

[ericgibbs]

To plot the voltage across R2

Run the Sim
Place mouse cursor RED probe, on the top end of R2, press and hold down the LEFT mouse button, a second BLACK probe will appear.

Keep the mouse button pressed and place the cursor BLACK probe on the bottom end of R2

The plot should now show volts across R2

 

[aljamri]

Thank you Eric, thats it.

See you with more questions

 

[aljamri]

New question:

Trying to recreate the circuit in post #5 of this thread by crutschow, I did not add anything except than the components. When run the simulation , got the error message in the attachment , added the red circled text and everything went OK.

My questions are:
1- Where did this line came from, or simply I have to type it ?
2- What dose it mean ?


Thanks

 

[aljamri]

New question:
Trying to recreate the circuit in post #5 of this thread, I did not add anything except than the components. When run the simulation , got the error message in the attachment , added the red circled text and everything went OK.

My questions are:
1- Where did this line came from, or simply I have to type it ?
2- What dose it mean ?

Thanks

 

[ericgibbs]

New question:
Trying to recreate the circuit in post #5 of this thread, I did not add anything except than the components. When run the simulation , got the error message in the attachment , added the red circled text and everything went OK.

My questions are:
1- Where did this line came from, or simply I have to type it ?
2- What dose it mean ?

Thanks

hi,
You have to declare on the circuit diagram the sub/model that you are using, it tells LTS where to look for the sub circuit, yes, type in that line.

If it still gives a problem, post your asc file.

 

[aljamri]

Hi Eric,

No, after I added the messege in the circle, everything went OK.

I'm just asking, adding this possible only by adding a text ?

 

[ericgibbs]

hi.
Try this,
Delete the OPA from the circuit
F2, Opamps.......... select a OPA type you may recognise from the list.
Double click on it and place it on the circuit where the 'old' used to be.

You shouldn't need the include
Right click that '.include' use the Radio buttons to make it into a Comment [ it wil lbe ignored when you run the Sim] or you could just delete it.

 

[crutschow]

All the commercial op amp models have the model parameters built-in so you don't need anything additional when you use those. The ideal op amp schematic icon does not have the model parameters included so you need to have the ".include opamp.sub" statement which adds the default ideal parameters. The opamp.sub file that's included is located in the LTC\LTspiceIV\lib\sub directory.