Warning! Symbulator's (Expert) mode is for expert users only. A considerable amount of knowledge on a) circuits theory, b) Symbulator's concepts and c) TI-89 use are required. Novice users should NOT attempt to use it until enough experience is acquired, or else... |
For the novice user, Symbulator is sort of a black box, in which you enter a circuit description and receive some answers. The (Expert) mode allows expert users to make a hole in that box to cast some light in the process, in order to read, modify and keep the equations involved in the symbulation process.
Previous to the (Expert) mode explanations, I want to teach you two things that any expert Symbulator user must know:
First lesson
1. When symbulating AC or DC analysis, you don't need to use five
terms in elements description if there are no ideal transformers in the circuit.
2. When symbulating in AC, if you plan to manipulate later the symbolic
expressions you obtain, you must give complex names to elements and
nodes, and complex values to those symbolic valued elements to avoid unexpected results.
Remember that the TI-89 will only recognize a variable as complex if its name ends in
"_". So, in AC symbulations in (Expert) mode
that imply manipulation after
the Symbulator ends, you must name elements as described below:
e1_,a_,0,vs_
You can see that element's name (e1_), node's name (a_) and element's symbolic value (vs_) end all in _. This implies that
all variables created, such as voltages, currents and powers, will also end in _. As I
said, this is only necessary if you will manipulate the equations.
Second
lesson
Under normal operation, my software first generates a set of 1st level equations and a
list of 1st level unknowns. These 1st level unknowns are voltages of nodes and
currents of voltage sources and inductors, among others. After these equations
are solved for these unknowns, a bunch of 2nd level expressions for 2nd level unknowns,
which were generated while the first set was being written, will also be evaluated.
These 2nd level unknowns are currents in resistors and capacitors, among
others. After this, a bunch of 3rd level expressions for 3rd level unknowns will be
generated and evaluated. These 3rd level unknowns are the real or complex powers
of DC or AC analysis.
1st level equations are functions of 1st level unknowns and elements
values. 2nd level expressions are also functions of 1st level
unkowns and elements values. 3rd level expressions are functions of 1st
and 2nd level unknowns and elements values.
Now, let's learn how to use the (Expert) mode.
To symbulate using the (Expert) mode, run.
sq\Expert()
You can help yourself with the typing using the Custom Menu's F5 items.
Instantly, a prompt appears asking you to select between DC and AC symbulations. Select the one you need. After some seconds, a Dialog box appears, asking you to select the work settings. These settings are the number of display digits and the format.
Suggestion! I recommend you to use 9 and Normal, unless you have specific reasons for choosing another settings. |
After some seconds, another Dialog will appear.
If the 1st level equations set is smaller than 250 characters, the dialog will include the following fields:
1. 1st level var's or First level unknowns. These are the unknowns for which Symbulator will solve first. They are: a) the voltages of the nodes, b) the currents for the voltage sources, inductors and other special elements. You can replace one or more of these variables for others, but in a 1 for 1 rate.
2. 1st level eq's or First level equations. These are the equations for which Symbulator will solve first. They are: a) the nodal analysis equations of each node, b) the special equations of voltage sources, inductors and other special elements. You can edit these equations if you wish, but that would alter the answer.
The number of 1st level unknowns and 1st level equations must be equal in order to find a solution. You can add a new variable for each new equation you add.
3. Known var's names or Known answers names. This are the names of those answers which value we already know, for the problem statement declares them. In the case there is more than one name, the names must be entered separated by commas, as shown: name,name,name.
4. Known var's values or Known answers values. This are the definitions of the answers listed above. Definitions must be as follow: name=value. In the case there is more than one definition, they must be separated by and's, as shown: name=value and name=value and name=value.
Below these, is a drop down menu:
5. Do in 1st level? or What do you want me to do with 1st level equations and unknowns? You can choose from three options:
a. Symbulate. or Only Symbulate them. If you choose this, the Symbulator will symbulate the equations and unknowns, considering of course any modification you've made to them, and any condition of known answer you've defined. At the end, you'll have stored in memory the voltages, currents and powers as usually.
b. Symbulate+ Keep or Symbulate, keeping a string copy of the equations, the unknowns and the known conditions. If you choose this, the Symbulator will symbulate as above, storing in memory the answers as above, but it will also save two or three new variables called equation, unknown and whenequs. The first is a string of the equations, the second is a string of a list of the unknowns, and the third is a string of the equations of known answers.
c. Just Keep or Do not symbulate, just keep a string copy of the equations, the unknowns and the known conditions. If you choose this, the Symbulator will NOT symbulate, but only save two or three new variables called equation, unknown and whenequs, meaning the same exposed above.
Notice! The input fields of TI-89 Dialog boxes are limited to 255 characters. So, to avoid clogging them, the Symbulator will activate an auxiliar mode in case the 1st level equations set is larger than 250 characters. If you experience that you cannot add new characters in the field, but still prefer the input fields dialog box, try again with a smaller display digits number (changing it in the first Dialog). |
If the 1st level equations set is larger than 250 characters, this set will be Only Kept by default and a dialog will appear with a warning: 1st level equations set is too large to display, so it will be kept.
Whether if you choosed Only Keep or if your set was kept by default for being too large, you will be prompted a new dialog.
Choose or What do you want me to do with 2nd level unknowns expressions? 2nd level unknowns are those which are neither 1st level unknowns (which you can saw in the previous dialog) nor powers. E.g. currents in resistors, capacitors and so. Expressions for these unknowns as functions of 1st level unknowns have been generated, and you can decide wheter to keep them or not. If you choose Delete, the program will delete them. If you choose Keep, the program will keep them. (Hehe! You cannot say my documentations are not clear, right?) If you choose Keep, a new Dialog will appear.
Choose or Do you want me to generate 3rd level unknowns expressions? 3rd level unknowns are consumed powers. E.g. variables starting with p or s. Expressions for these unknowns as functions of 1st and 2nd level unknowns have not been generated yet, but you can decide wheter to generate them or not. If you choose Do nothing, the program will not generate them. If you choose Generate, the program will... well, I'll let you guess what it will do.
You should keep (2nd level) and generate (3rd level) expressions only if you have reasons to think that you will use those expressions later. Otherwise, it is not necessary.
Warning! The equations kept by this Just Keep feature of the (Expert) mode should not be used for symbulations of circuits that include OpAmps. The reason is simple: OpAmps require all answers to be applied a limit() command, and both of these tasks are made when the answers are solved and stored, in a posterior command line inside the code, which is not the case here, because you are keeping them before they are solved. |
Suggestion! Do not worry if you feel this is messy by now: read the solved advanced examples and you'll see all clear. |