This document describes various simulation tools available in ECD302 including the 555 timer wizard, filter wizard, CE BJT amplifier wizard, component tolerance settings, creating sub-circuits, and post-processing tools. The 555 timer and filter wizards allow designing oscillator and filter circuits by entering specifications. The CE BJT amplifier wizard designs common emitter amplifiers. Component tolerance can be enabled or disabled. Sub-circuits help organize large designs. Post-processing derives new results from simulation data using formulas. An example calculates instantaneous power from measured voltage.

1. ECD302
Miscellaneous Simulation Tools

2. Miscellaneous Simulation Tools
555 timer wizard
Filter wizard
CE BJT Amplifier wizard
Component tolerant
Creating Sub-circuits
Post processing

3. 555 timer wizard
Use the 555 Timer Wizard to
build astable and monostable
oscillator circuits that use the
555 timer
Two types:
•Astable Operation
•Monostable
Operation

4. 555 timer wizard
Source
voltage
Astable
Operation-
produces a
free-running
oscillator that
does not need
any input
signal.

5. 555 timer wizard

6. 555 timer wizard
Monostable
Operation-produces
a single output
pulse in response to
an input trigger
pulse. When an
input signal is
applied, each input
pulse will produce
one output pulse.

7. 555 timer wizard

8. Filter wizard
The Multisim Filter
Wizard lets you
design numerous
types of filters by
entering the
specifications into
its fields.

9. Filter wizard
Low pass filter
High pass filter
Band pass filter
Band reject filter

10. Filter wizard
Low pass filter
At high frequency,
the output starts to
drop to stop.

11. Filter wizard
High pass filter
Low pass filter
High pass filter
Band pass filter
Band reject filter

12. Filter wizard
High pass filter
At low frequency,
the still low output.

13. CE BJT Amplifier wizard
Wizard lets you design
common emitter
amplifier circuits by
entering the desired
specifications into its
fields. The designed
circuit can then be
verified by SPICE
simulation directly.

15. CE BJT Amplifier wizard

16. Component Tolerance
When the output of your circuit is
slightly different from theoretically
prediction, do not be too quick to blame
the component tolerance.
In MultiSIM, the component tolerance is
DISABLED, by default. This means, by
default, all your component values are
simulated “exactly as is”. No tolerance.

17. How to know it is DISABLED?
As shown here:
When enabled, there will
be a “tick” here.

18. When it is ENABLED…
You will see the
option selected:
The “tick”.


19. With tolerance disabled…
In this example, the component
tolerance is disabled. You should get
the same resistance reading from all
meters:
Filename:
L4_cct01.msm

20. Enabling component
tolerance…
You will be
prompted with
this screen. Just
set the
percentage of
tolerance you
want, and click
“OK”…
Only this field is editable
because our circuit has only
resistors…

21. With tolerance enabled…
You should now see the component
values all different…
All the set values are still 1 kΩ…
…but all the
component
values are
now different.

22. Virtual vs. Real components
Now, perhaps you have noticed that the
component tolerance seems to be
applicable only to VIRTUAL
components… what about REAL
components?
Does this mean
that REAL
components
have no
tolerance?

23. Real components, tolerance
disabled…
Of course, there is no tolerance…
Filename:
L4_cct02.msm

24. Real components, tolerance
enabled…
There is no tolerance either! So, we can
see that REAL components in MultiSIM
are not subjected to tolerance.

25. Creating Sub-Circuits
When designs get HUGE, it is always a
good practice to manage your circuits in
smaller “chunks”.
Such practice is especially useful when
your design has multiple parts of the
same circuit patterns. We will look at an
example in the following slides.

26. A 2-stage Common Emitter
Amplifier
Filename:
L4_cct03.msm

27. Repeated design pattern
You can see that the
2 stages of common-
emitter amplifiers are
actually the same.

28. Creating a Sub-Circuit
We will copy
this part into a
new file, and
add to it some
input/output
terminals to
save it as a
sub-circuit file.
Filename:
L4_cct04.msm

29. Using the sub-circuit
Whenever you need
to use the sub-circuit,
open the file, copy
the whole circuit, then
open a new
document (or an
existing document
where you want this
sub-circuit to be
added to). Select all and copy.

30. Pasting as sub-circuit
In the new document
(or existing document
you want to add the
sub-circuit to), just
click on any empty
space on the design
sheet, then choose to
“paste as subcircuit”.

31. Naming sub-circuit
Paste the sub-circuit twice, to get the
two stages. Name your two stages
differently.
You should get this:

32. Just use it!
Make similar connections as the earlier
circuit:
Filename:
L4_cct06.msm

33. Results comparison
You can see from the oscilloscope
displays below that the full circuit and
the circuit with sub-circuit function
exactly the same:
From L4_cct03.msm From L4_cct05.msm

34. Post-Processing
Post-processing makes up for what
analysis is lacking in the MultiSIM
package.
It basically takes the results of other
analyses to produce a derived set of
results according to formulae specified
by the user.

35. Instantaneous Dissipation of
Power
For example, MultiSIM does have a
wattmeter, but it measures the RMS
power, and furthermore, the time-
varying results are not recorded. If we
wish to record instantaneous power
dissipated in a component as time
varies, we would find the wattmeter
incapable of doing that.

36. Post-Processing to the
rescue!
To make up for that lacking, we could
actually use the post-processing
capability of MultiSIM to do what we
want.
The process of doing so will be
illustrated in the following slides.

37. Example
Let us use an example of series RLC
circuit, as shown below, from which we
wish to find the instantaneous power in
the resistor:
Filename:
L4_cct08.msm

38. The process before the “post”
process…
Before we could use the post-
processing capability, there must be
some prior results from which the post-
process could derive the required data.
For finding power, we could use the
formula: P = V2
/R. So, we should at first
measure the instantaneous voltage
across the resistor.

39. Transient Analysis to get the
voltage across the resistor…
The voltage across the resistor could be
measured using the transient analysis,
where we would set the output variable
as “voltage at node 3”, as shown below:

40. Other settings…
We should also set the start and stop
time for the transient analysis. With the
input frequency being 100 kHz,
simulating for 0.1 ms should be enough
to get us results over 10 cycles:
Set the stop time
as 0.1 ms after
starting.

41. Data
The results
are displayed
– and stored
until program
shutdown – in
the grapher,
as shown
here:

42. Invoking the Post-Process
After obtaining the
data for
instantaneous
voltage, we can
now invoke the
post-process (look
under “Simulate”
from the menu).

43. Put in the required formula. R1 is 1 kΩ, hence the 1000.
Highlight the name
of the previous
analysis from which
you wish to derive
the data.
Variable(s) available in the
previous analysis that you
have specified in the field to
the left of this.
Mathematical
functions that you may
use in the post-

44. Further settings…
Upon clicking “new trace”, you will be
prompted for the name of the page; just
click “OK”:

45. Further settings…
Then you will be prompted for the name
of the graph. Rename or just click “OK”:

46. Then click “Draw” to draw the graph according to the formula
you specified:
This graph indicates the instantaneous power
dissipated in the resistor due to the AC input.

47. Exporting Data to MS Excel
You could also export the results of
your analyses to MS Excel for external
processing (if you find the post-
processing capability not up to par for
the further analyses that you want).

48. Exporting Data…
It is as easy as just clicking from the
menu the “export to Excel” function:

49. You will get two
columns of data in
MS Excel:
The first column is the data for
“time”, as our results were
simulated against time.
The second column is the
data, in this case, the
instantaneous power
dissipated in the resistor R1.

50. Limitation of Data Export
It should be noted, however, that at any
one time, you can only export ONE set
of data (that is, one column of time, and
another column of the currently active
trace).
If your graph has more than one trace
of data, only the currently active
(selected) trace will be exported.