Data Sheet

219
VSM TUTORIAL (Graphs)
The purpose of this tutorial is to show you, by use of a simple amplifier circuit, how to perform a
graph based simulation using Proteus VSM. It takes you, in a step-by-step fashion, through:
Placing graphs, probes and generators.
Performing the actual simulation.
Using graphs to display results and take measurements.
A survey of the some of the analysis types that are available.
The tutorial does not cover the use of Proteus in its general sense - that is, procedures for
placing components, wiring them up, tagging objects, etc. This is covered to some extent in the
Interactive Simulation Tutorial and in much greater detail within the Proteus manual itself. If you
have not already made yourself familiar with the use of Proteus then you must do so before
attempting this tutorial.
We do strongly urge you to work right the way through this tutorial before you attempt to do your
own graph based simulations: gaining a grasp of the concepts will make it much easier to
absorb the material in the reference chapters and will save much time and frustration in the long
term.
Getting Started
The circuit we are going to simulate is an audio amplifier based on a 741 op-amp, as shown
below. It shows the 741 in an unusual configuration, running from a single 5 volt supply. The
feedback resistors, R3 and R4, set the gain of the stage to be about 10. The input bias
components, R1, R2 and C1, set a false ground reference at the non-inverting input which is
decoupled from the signal input.
As is normally the case, we shall perform a transient analysis on the circuit. This form of
analysis is the most useful, giving a large amount of information about the circuit. Having
completed the description of simulation with transient analysis, the other forms of analysis will
be contrasted.