Data Sheet

LABCENTER ELECTRONICS LTD.
226
There is one final piece of setting-up to be done before we start the simulation, and this is to set
the simulation run time. Proteus will simulate the circuit according to the end time on the x-scale
of the graph, and for a new graph, this defaults to one second. For our purposes, we want the
input square wave to be of fairly high audio frequency, say about 10kHz. This needs a total
period of 100ms. Tag the graph and click left on it to bring up its Edit Transient Graph dialogue
form. This form has fields that allow you to title the graph, specify its simulation start and stop
times (these correspond to the left and right most values of the x axis), label the left and right
axes (these are not displayed on Digital graphs) and also specifies general properties for the
simulation run. All we need to change is the stop time from 1.00 down to 100u (you can literally
type in 100u - Proteus will covert this to 100E-6) and select OK.
The design is now ready for simulation. At this point, it is probably worthwhile loading our
version of the design (Open Sample -> Tutorials -> Analogue Simulation Tutorial (Part 2)) to
avoid any problems during the actual simulation and subsequent sections. Alternatively, you
may wish to continue with the circuit you have entered yourself, and only load the default file if
problems arise.