# Problems with a simulation

#### Oscar Ramirez

Joined Oct 12, 2015
3
Hello, well... I'm trying to simulate this circuit in PSPICE but when I run the simulation profile it seems that the circuit hasn't energy because there are no currents or voltages, I really don't know what is wrong.

This is the circuit:

look that there are not voltages or currents

This is the profile simulation:

and this is the output file:

PD: Forgive me for my English it is not my native language.

#### MikeML

Joined Oct 2, 2009
5,444
Hi Oscar,

Are you attempting to do an .AC solution at just one frequency of 39.87Hz?

The DC voltages at the various nodes are 0Vdc, as shown. That is not an error.

You need to figure out how to ask PSpice to show you what are the AC voltages at each node, and what are the AC currents in each of the branches...

#### Oscar Ramirez

Joined Oct 12, 2015
3

Yes only in the frequency of 39.87Hz, and I've understood that PSPICE could show me the AC current and voltage with those parts

but although I've used this in the circuit is does not shown me any voltage ac

#### MikeML

Joined Oct 2, 2009
5,444
Sorry, I cannot help you with PSpice. The last time I used it (without a graphical user interface) was about 30years ago...

I use the free LTSpice, which from postings like yours makes me think that it is far superior to various paid-for Spices like PSpice and others that use the stupid little measurement icons, which seem to do nothing but confuse.

LTSpice simply gives you the ability to run a simulation, and then ask for the node voltages or component currents after the fact. Here is your circuit, where the first thing I show is an .AC simulation at just a single frequencyof 39.78Hz. I labeled the nodes A, B, C, and D to make it easy to relate to the printed values of voltages at those nodes. The currents are referenced to the sources and passive elements.

The real power of the plotting window in LTSpice is apparent when you sweep the simulation frequency over a wide range of values... Here, in the same circuit, I simply replace the .AC list 39.78 single frequency point directive, with .AC dec 50 1 10k, which runs the simulation 200 times, 50 steps for each decade from 1Hz to 10kHz. The plot shows the magnitude and phase for each selected node in dbV (Bode plot).

Or if you prefer to plot the y-axis in absolute volts (rather than dbV), I just click on the Y axis, and change from log to lin.

#### Oscar Ramirez

Joined Oct 12, 2015
3
Great, thanks ... it seems that LTSpice is the easiest

#### mvaseem

Joined Jan 31, 2014
48
To plot in Pspice, you need to put probe on schematic.

For voltage plot - Put voltage probe on nets.
For current plot - Put current probe on part pins.