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FAQ's

Now that I use Symbulator, will I need SPICE again?

Of course you will! Remember that SPICE and Symbulator don't overlap or replace each other. Symbulator is for linear symbolic circuits; SPICE is for huge numeric non-linear circuits.

Do you have an anotated version of the program's code?

No, sorry. I know Symbulator's code is extremelly cryptic. I made it that way at hand, for it to be smaller and faster. Anyway, the code is copyrighted.

Does Symbulator runs in a TI-92Plus?

Although I don't owe a TI-92+, some friends have told me that it does run fine on the 92+.

What is the real name of your software?

Once it used to be named Symbolic Circuit Simulator, and SCS were its initials. Later, I named it Symbulator. (Expert) is the name of an operation mode.  (Impala) is the name of an inner method. Q is the name of the last version.

I am having a little trouble understanding the way current is defined through a voltage source. Can you explain this point?

Currents in elements are defined according to a convention used in all major circuit simulators. It is the standard convention in the world of circuit simulation. The rule says something like this:

1) Current in an element flows from the first node you define to the second node you define.

2) In voltage sources, the first node you define is positive node.

3) In current sources, the first node you define is the starting node.

That's why the current is defined that way, which seems to "opposite" to the natural flow of current inside a voltage source. Remember that the current in a given voltage source may flow in any direction, according to the circuit.

Is it possible to analyze a circuit that uses mutual inductances that are defined in the complex plane?

In Symbulator, mutual inductances should be defined in Henrys. Although, if you find a circuit with the mutual inductances defined as complex values, there is a trick you can use:

1) If there is a given frequency for the problem, then obtain, from the reactance of the mutual inductance in Ohms, its equivalent value in Henrys using the formula L in Henrys =X in Ohms / w, where w is radial frequency, or L = X / 2*Pi*f, where f is frequency in Hz.

2) If there is no given frequency for the problem, you assign an arbitrary frequency of 1 rad/seg and automatically you can use the Ohms values as if they were Henrys.

Would it be possible for Symbulator to solve circuits that includes diodes?

Symbulator cannot solve circuits that includes diodes. Although, you can solve circuits that includes diodes using Symbulator as a modeling tool.

Since Symbulator is a linear circuit simulator, it does not accept or simulates any non-linear element (semiconductors). For non-linear elements I strongly recommend the use of a numerical simulator, such as SPICE, PSpice or Electronic Workbench. The reason for this limitation has to be searched in the same nature of Symbulator. Symbulator is a symbolic simulator. Semiconductors behavior depends on the value of voltages and currents in their terminals. How can we know the value of a symbolic current? It is easy to see that to have a symbolic value is to have an unknown, and a diode or a transistor require us to know the numerical value of this unknown (beside the grafic of its features), this is to say the numerical value on which its behavior depends.

Now, since non-linear elements can be modeled, what you can do in some cases to solve circuits that includes diodes is to modelate this non-linear elements using linear equivalents. How? Well, diodes can be modeled as short circuits and open circuits, depending on their state. Zener diodes can be modeled as a voltage source (examples are there in the site). Transistors can be modeled using hybrid parameters.

Symbulator won't simulate a circuit using non-linear elements, but will allow you (as it has allowed me during my electronics 1 and 2 courses) to model this non-linear elements with their linear elements, and get the right (symbolic) answer.