Due to the widespread development of computing devices, the task of calculating and modeling electrical circuits has become noticeably simplified. The most suitable software for these purposes is the National instruments product – Multisim (Electronic Workbench).
In this article we will look at the simplest examples of modeling electrical circuits using Multisim.
So, we have Multisim 12, which is the latest version at the time of writing. Let's open the program and create a new file using the Ctrl+N combination.
After creating the file, the work area opens in front of us. In fact, the Multisim work area is a field for assembling the required circuit from existing elements, and, believe me, their choice is great.
By the way, briefly about the elements. All groups are located on the top panel by default. When you click on any group, a context window opens in front of you in which you select the element you are interested in.
The default element base is Master Database. The components contained in it are divided into groups.
Let us briefly list the contents of the groups.
Sources contains power supplies, grounding.
Basic – resistors, capacitors, inductors, etc.
Diodes – contains various types of diodes.
Transistors - contains various types of transistors.
Analog - contains all types of amplifiers: operational, differential, inverting, etc.
TTL - contains elements of transistor-transistor logic
CMOS - contains elements of CMOS logic.
MCU Module – multipoint communication control module.
Advanced_Peripherals – external devices to be connected.
Misc Digital - various digital devices.
Mixed - combined components
Indicators - contains measuring instruments, etc.
The modeling panel is also nothing complicated, just like on any playback device there are start, pause, and stop buttons. The remaining buttons are needed for modeling in step-by-step mode.
The instrument panel contains various measuring instruments (from top to bottom) - multimeter, function generator, wattmeter, oscilloscope, Bode plotter, frequency meter, word generator, logic converter, logic analyzer, distortion analyzer, benchtop multimeter.
So, having briefly examined the functionality of the program, let’s move on to practice.
Example 1
First, let's assemble a simple circuit; for this we need a direct current source (dc-power) and a pair of resistors (resistor).
Let's say we need to determine the current in the unbranched part, the voltage on the first resistor and the power on the second resistor. For these purposes we will need two multimeters and a wattmeter. Switch the first multimeter to ammeter mode, the second to voltmeter mode, both to constant voltage. We connect the current winding of the wattmeter to the second branch in series, the voltage winding in parallel with the second resistor.
There is one feature of modeling in Multisim - grounding must be present in the diagram, so we will ground one pole of the source.
After the circuit is assembled, click on start simulation and look at the instrument readings.
Let's check the correctness of the readings (just in case =)) according to Ohm's law
The instrument readings turned out to be correct, let’s move on to the next example.
Example 2
Let's assemble an amplifier using a bipolar transistor using a common-emitter circuit. We use a function generator as an input signal source. In the FG settings, we will select a sinusoidal signal with an amplitude of 0.1 V and a frequency of 18.2 kHz.
Using an oscilloscope, we will take oscillograms of the input and output signals; for this we will need to use both channels.
To check the correctness of the oscilloscope readings, we will place a multimeter at the input and output, having first switched them to voltmeter mode.
We launch the circuit and double-click each device.
The voltmeter readings coincide with the oscilloscope readings, if you know that the voltmeter shows the effective voltage value, to obtain which you need to divide the amplitude value by the root of two.
Example 3
Using logical elements 2 AND-NOT, we will assemble a multivibrator that creates rectangular pulses of the required frequency. To measure the pulse frequency, we will use a frequency counter, and check its readings using an oscilloscope.
So, let’s say we set a frequency of 5 kHz, and empirically selected the required values of the capacitor and resistors. We run the circuit and check that the frequency meter shows approximately 5 kHz. On the oscillogram we mark the period of the pulse, which in our case is equal to 199.8 μs. Then the frequency is
We have considered only a small part of all possible functions of the program. In principle, Multisim software will be useful both for students for solving problems in electrical engineering and electronics, and for teachers for scientific work, etc.
We hope this article was useful to you. Thank you for your attention!
Provides tools for creating electrical circuits, as well as for designing and routing printed circuit boards, which is done in the Ultiboard editor. Ultiboard is used for the development of printed circuit boards, preparing design results for production, has the ability to automatically place components on the board and automatic routing, and also provides developers with the opportunity to work in its environment as a 3D modeling system, as a result of which the printed circuit board and its components will be displayed in real form. Ultiboard tools allow you to create 3D models of components from flat graphical data from libraries of topological footprints, develop your own models by importing complex contours of components from mechanical CAD systems, and also using a special wizard. Board routing in Ultiboard can be done manually or automatically.
Automatic routing of conductors in Ultiboard.
Automatic conductor routing involves the use of special tools that independently lay out printed conductors (sections of a conductive coating applied to an insulating base, equivalent to a regular installation wire) based on design rules specified by the developer. You can set autorouting settings in the “Autorouting Options” window, which can be accessed using the “Autorouting/Autorouter/Installer Settings” command in the Ultiboard main menu. The Auto Trace Options dialog box contains the following tabs:
Rice. 1. Autotrace Options dialog box:(a) Basic tab, (b) Estimated tab, (c) Gaps tab, (d) Optimization tab, (e) Auto Placement tab, (f) Tires tab.
To set the basic auto-routing parameters, use the “Basic” tab (Fig. 1a). In its upper part there is the “Trace” field, in which you can set the tracing mode, grid settings, and the need to optimize the project (set by checking the “Optimization” checkbox). Enable optimization allows the router to make additional passes to optimize wire placement. Optimization starts after the trace is completely completed. The tracing mode is set by selecting one of three values from the drop-down list:
For the changes to take effect, click the OK button.
The autorouter algorithm uses evaluation parameters to develop a strategy for laying conductors and installing vias. Viewing and editing of estimated parameters is carried out on the “Estimated” tab of the “Auto-routing parameters” dialog box (Fig. 1b).
When making changes to the default parameters, the developer must take into account that these parameters are optimal. For best results, it is not recommended to change them in most cases. If the developer still considers it necessary to select his own values in the settings of the “Evaluation” tab, he should be aware that even minor changes in parameters can worsen the performance of the autorouter. You should not change more than two estimated parameters at the same time or make changes with large deviations from the recommended ones. The developer also needs to know that most of the evaluation parameters are interrelated and changing one of them can lead to difficulties in calculating others.
Let's look at the “Breaks” tab (Fig. 1c). Here you can configure the board wire break parameters. High values of the discontinuity parameters increase the intensity of the algorithm for applying this operation. In the “Advanced” field, by checking the “Memory clearing during tracing” checkbox, you can, if necessary, set permission to clear memory to remove unnecessary information from it.
If allowed, once the routing is complete, an optimization process is initiated in which the router makes additional passes to optimize the placement of the wires. Optimization parameters (the number of passes of the optimization algorithm after completion of tracing and the direction of optimization) are set on the tab of the same name (Fig. 1d) of the “Auto-trace parameters” dialog box. The “Advanced” field sets permission to clear memory during optimization.
On the “Auto-placement” tab (Fig. 1d), the following parameters for auto-placement of components on the board are set: number of entries, pin factor, case factor, resolution of rotation of components during auto-placement, minimum interval between components on the board, permission to change pins/sections/cases for the most optimal auto placement of components. To configure bus routing parameters, use the “Bus” tab (Fig. 1e).
Automatic routing is launched using the main menu command “Auto routing/Run/view auto routing” after setting the routing parameters and placing components on the board. Figure 2 shows the result of automatic tracing of the electrical circuit diagram of the power supply (Figure 3). The project transferred from Multisim is shown in Figure 4. Figure 5 shows the placement of components on the boardin the workspace of the Ultiboard program.
Rice. 2. The result of automatic routing of board conductors.
Rice. 3. Electrical circuit diagram of the power supply.
Rice. 4. Project imported from Multisim.
Rice. 5. Placing components on the board in the workspace of the Ultiboard program.
3 D visualization of the developed board.
The Ultiboard program allows you to view the designed board in 3D. To view the board in three dimensions, you must select the “3D View” command in the main menu of the “Toolkit” program, as a result of which a new “3D View” tab will be opened in the project (Fig. 6). To get the most complete picture of the dimensions of the developed board, the 3D image on this tab can be rotated in all planes. By manipulating the cursor with the mouse, you can change the viewing angle and the position of the board in space. By rotating the mouse wheel you can scale the 3D image of the board. On the “3D View” tab there is a development panel, which contains two tabs: “Projects” and “Layers”. You can control the display of elements of the 3D image of the board (components, silk-screen printing, conductors, board, pins) by checking/unchecking the corresponding checkboxes on the “Layers” tab.
Rice. 6. 3D view of the printed circuit board: (a) from the components side, (b) from the back side of the board.
Manual routing of conductors in Ultiboard.
For manual routing, the Ultiboard system offers the following tools:
These tools are available from the main “Insert” menu or from the “Home” toolbar. The easiest and fastest way to manually lay routes is to use the Point to Point tool. The sequence of actions when working with this tool can be as follows:
Rice. 7. Selecting a communication line using the Point to Point tool.
Rice. 8. The route options for the conductor proposed by the system in the “Point to Point” mode.
Rice. 9. Manual routing of several conductors in the “Point to Point” mode.
It should be noted that using the “Point to Point” tool you cannot connect a large number of pins at the same time, that is, route the entire circuit at once. There is another tool for this in Ultiboard - “Follow Me”. The sequence of actions when working with this tool can be as follows:
Rice. 10. Selecting a chain using the Follow Me tool.
Rice. 11. Tracing a circuit using the Follow Me tool.
When using the Line tool, responsibility for the route of the route lies entirely with the designer. In this case, the system can indicate errors made by him using colored markers that appear in the places where errors occurred (Fig. 12).
Rice. 12. Colored markers in places where errors occurred and information about errors made during manual tracing.
The sequence of actions when working with this tool can be as follows:
Information about errors received as a result of routing is displayed on the “DRC” tab of the “Information Block” panel.
Manual tracing can be optimized. This can be done using the main menu command “Autotrace/Run optimizer”. In this case, the conductors and vias of the board must have permission to move, which can be set on the “Basic” (Fig. 13) and “Via” (Fig. 14) tabs of the properties dialog box for these elements in the “When autorouting” field.
Rice. 13. “Basic” tab of the “Explorer Properties” dialog box.
Rice. 14. Via tab of the Via Properties dialog box.
For example, consider an amplifier stage based on a bipolar transistor - connected to a circuit with a common emitter. Let's plot the dependence of the output and input voltages on time, the transfer characteristic, the amplitude-frequency and phase-frequency characteristics.
1) Let's assemble the circuit under study in the Multisim environment
Note:
- double-clicking the left mouse button on an element allows you to change its parameters
-for convenience when working, you can change the color of the wires (select the wire with the right mouse button and select Change Color in the context menu that appears)
2) We launch the circuit, the oscilloscope automatically builds graphs of the dependence of the input and output voltages on time (in order to view them, just left-click on the oscilloscope).
In the active Oscilloscope-XSC1 window, you can zoom in and out, shift the graphs along the ordinate and abscissa axes, use the cursor to view the parameters at each point of the graph (here, the voltage value), using the Save button you can save the oscilloscope data in the form of a table in a text file .
3) Construction of similar graphs using Transient Analysis.
Using the plotter button to display cursors and data, you can see the voltage value at any point. During analysis, graphs are displayed in different colors for convenience.
In the Transient Analysis window, on the Output tab, select the quantities necessary for analysis, and on the Analysis Parameters tab, you can set the start and end times of the analysis (the same actions are performed in any type of analysis).
4) Construction of the transfer characteristic (dependence of the output voltage on the input) using DC-Sweep Analysis. Working with a graph in a plotter (Grapher View) is done in the same way.
5) Construction of frequency response and phase response (using AC-Analysis).
The first stage in creating an electrical circuit in the Multisim program was the stage of selecting the required microprocessor from the library (Figure 2.4) and setting its initial parameters.
Figure 2.4 – Component selection window.
The microprocessor chosen was Intel 8051 in a DIP-40 package.
Figure 2.5 – Microprocessor settings window (step 1).
In the first setup step (Figure 2.5), the name of the workspace and where it will be located are indicated.
Figure 2.6 – Microprocessor settings window (step 2).
In the second setup step (Figure 2.6), the type of microprocessor design is indicated. For greater simplicity, the type was chosen using an external hex file, which contains ready-made microprocessor firmware.
Figure 2.7 - Microprocessor settings window (step 3).
In the final setup step (Figure 2.7), it is indicated whether a ready-made project will be used or an empty project will be created.
After all setup steps are completed, you go to the microprocessor settings. The settings indicate the amount of built-in internal RAM, built-in external RAM, the amount of ROM, and the clock frequency at which the microprocessor operates.
To add the firmware file, you need to go to the “MCU Code Manager” section. Next, select the project that was created when setting up the microprocessor and specify let for the machine code file for simulation. The MCU code manager window is shown in Figure 2.8.
Figure 2.8 – MCU code manager.
After adding the firmware, its functionality is checked and the memory is checked for errors when uploading the firmware to the microprocessor (Figure 2.9).
Figure 2.9 – Memory viewing window.
Arduino Uno Shield was chosen as the layout on which all the elements of the circuit are located, which represents an empty board on which only outputs for connecting sensors are located. 
Figure 2.10. - Arduino Uno Shield in Multisim program.
After creating the layout in the Multisim program, this circuit was translated into the Ultiboard program to create its 3D model (Figure 2.11) and the arrangement of elements on the board (Figure 2.12). The 3D model shows what our design will look like even before it is manufactured.
Figure 2.12 shows the arrangement of elements on the printed circuit board. It is necessary to create a template from which the first test samples will be made.
Figure 2.11 – 3D model of Arduino Uno Shield in the Ultiboard program.
Figure 2.12 - Arduino Uno Shield in Ultiboard program
Figure 2.13 – Finished development in the Multisim program.
After creating the circuit in the Multisim program, it was translated into the Ultiboard program to create a 3D design model (Figure 2.14), the arrangement of elements on the printed circuit board and the layout of elements on the printed circuit board (Figure 2.15).
Figure 2.14 - 3D model of the finished development in the Ultiboard program.
Figure 2.15 – Printed circuit board of a finished design in the Ultiboard program.
The entire creation of the development can be represented on the block diagram shown in Figure 2.16.
Figure 2.16 – Let the development be created.
BUSINESS PLANNING AND DIPLOMA PROJECT MANAGEMENT
