Creating electrical circuits involves drawing them on the working field. At the first stage after starting the program, you need to remove the required elements from the libraries and then connect them in a given way.
To remove an element from the library, you need to single-click the left mouse button on the library. A window with library components will appear. Then, by clicking once on the element, you need to move the mouse pointer to the work field, after which, by clicking the mouse on any point of the work field, you place the element there.
The connection of elements is carried out as follows: when you hover the mouse pointer over one of the element’s clamps, it will take the form of a cross, then by clicking the left mouse button once, begin to move the mouse pointer. A dotted line will follow it. To make a line bend at a given point, click the left mouse button. When you move the mouse pointer to a free element pin, node or conductor (connector line) and left-click, a line connecting the elements (conductor) will appear.
The conductor resistance in Multisim is zero. It must be borne in mind that the circuit must be grounded, and at least one measuring device must be present in the working field. Grounding is connected to any point in the circuit.
When the circuit is assembled and all the necessary measuring instruments are connected, you can start the simulation (turn on the circuit). Switching on is carried out by the switch in the upper right corner of the screen. After turning on the circuit, the model begins to work. After removing the necessary data, the circuit must be turned off. Any changes to the circuit are possible only in disabled mode.
GOAL OF THE WORK
Studying and gaining skills to work in the program Multisim
TASK FOR WORK
Study the principle of constructing electronic circuits in the program Multisim
GENERAL INFORMATION
The organization of the Multisim program interface is shown in Fig. 1. Shown here is a standard toolbar containing buttons for the most commonly used program functions.
The simulation panel allows you to start, stop and other simulation functions described below.
The toolbar has buttons for each of the used tools, selected from the Multisim database/
The general development panel shown in Figure 1. contains a circuit window in which the circuit under study is located.
The standard panel contains the following buttons:
The following buttons are located on the toolbar:
Finally, the Components panel shows the following elements:
Tools
Multisim has a number of virtual instruments. These devices are used in the same way as their real-life equivalents. Using virtual instruments is one of the best and easiest ways to explore a circuit. These devices can be placed at any circuit or subcircuit level, but they are only active for the current circuit or subcircuit on the active components.
Virtual instruments come in two forms: an instrument icon, which you install on your diagram, and an open instrument, where you set how the instrument is controlled and displayed on the screen.
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The fixture icon shows how the fixture is associated with the circuit. When an instrument is active, a black dot inside the I/O indicators indicates that the instrument is connected to a branch point.
Adding a device to the circuit:
1. By default, the dashboard is displayed in the workspace. If the toolbar is not displayed, click the Instruments button. The Instruments Toolbar appears, with each button representing one instrument.
2. On the Instruments toolbar, click the button for the instrument you want to use.
3. Move the cursor to the place in the diagram where you want to place the device and click on the mouse button.
The tool icon and ID will also appear. The instrument identifier identifies the type of instrument and its sample. For example, the first device you place on the diagram will be called "XMM1", the second - "XMM2", and so on.
Note: To change the color of the Instrument icon, right-click on it and select Color from the context menu. Select the color you want and click OK.
Use of the device:
1. To view and change instrument controls, double-click the instrument. The Tool control window will appear. Make any necessary changes to the settings just as you would on their real-life equivalents.
Please note that the settings must match your circuit. If the settings are incorrect, it may distort the simulation results.
Note: Not all areas of an open appliance can be modified. A hand sign appears when the cursor is on a setting that can be changed.
2. To "activate" the circuit, click the Simulate button on the Control Panel, and select Run from the pop-up menu that appears. Multisim will begin to simulate the behavior of the circuit and the values of the measured parameters at the points to which you connected the device.
While the scheme is active, you can adjust the tool settings, but you cannot change the scheme by changing values or performing any actions such as rotating or moving an element.
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 runs 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 started 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 times when electrical circuits were drawn on paper by hand are a thing of the past. At the moment, the vast majority of specialists develop a set of design documentation using special programs, one of which is Multisim. The Multisim system is at the same time a circuit editor that allows you to develop complex electrical circuit diagrams and an application for their simulation. Multisim is designed to input the schematic as well as prepare for the next step, such as PCB layout.
Working with hierarchical blocks and subcircuits.
If the circuit being developed contains several nodes of the same type, hierarchical structures (hierarchical blocks and subcircuits) can be used to build it. In this case, in the diagram, each node will be represented by a special component (“black box”) in the form of a rectangle with pins. The diagram of each node is constructed on a separate sheet. The hierarchical block diagram is stored in a separate file with the extension *.ms12 (this file is referenced by the main diagram file). The subschema is stored together with the main schema. Any fragment of the diagram can be designed as a hierarchical block, and then placed on the diagram, which allows you to reduce its size. Since the hierarchical block is actually a separate file, it can be edited as a separate diagram. Hierarchical blocks and subcircuits allow you to divide a complex project into smaller interconnected circuits.
A new project just created in Multisim by definition becomes the top-level circuit in the current design. All subcircuits and hierarchical blocks referenced by this file will appear as subordinates in the project tree.
In order to add a hierarchical block to the diagram being developed, you must select “New hierarchical block” from the “Insert” menu. As a result, a window of the same name will open (Fig. 1) in which you must specify the name of the new hierarchical block diagram (the “Hierarchical block file” field) and the number of input and output pins of the hierarchical block (the “Input pins” and “Output pins” fields), and then click on the “OK” button.
Rice. 1. "New Hierarchical Block" dialog box.
You can select the location of the hierarchical block diagram file as follows:
After completing the actions, all dialog boxes will be closed, and the created hierarchical block will be attached to the mouse cursor, which can be immediately connected to the circuit circuit or simply placed on the drawing by clicking the left mouse button in the required place. The name of the new hierarchical block will appear in the project tree on the Structure tab of the Design Panel. Select the line with the name using the left mouse button in order to go to the diagram sheet of the newly created hierarchical block. You can also go to the diagram sheet in another way:
Rice. 2. Multisim project in which there is a hierarchical block.
The schematic sheet of the newly created hierarchical block is a normal Multisim circuit design sheet and contains the pins connecting the block to the main circuit. Contacts are added to the block diagram automatically, and their number depends on the number that you entered in the “Input Pins” and “Output Pins” fields of the “Hierarchical Block File” dialog box when creating the hierarchical block. Now that you are in the working field of the hierarchical block diagram, all that remains is to create the necessary node and connect its pins to the contacts connecting the block to the main circuit (Fig. 3).
Rice. 3. Diagram of a hierarchical block.
You can also add a hierarchical block to the diagram being developed from an existing file. To do this, you need to select the “Hierarchical block from file” item in the “Insert” menu and in the Windows Explorer window that opens, select the required diagram file using the left mouse button, and then click the “Open” button. After which the Windows Explorer dialog box will be closed, and the created hierarchical block will be attached to the mouse cursor, which can be immediately connected to the circuit circuit or simply placed on the drawing by clicking the left mouse button in the required place. After opening the diagram sheet of the created hierarchical block, the diagram from the file will be placed in the work field. After creating a hierarchical block from a file, IS/PS connectors are automatically added to it (based on the analysis of circuit circuits from the file). If this does not happen, connectors must be added manually. To do this, go to the hierarchical block diagram and in the “Insert/Connector” menu select “Output hierarchical block/subcircuit”. Add the required number of connectors to the drawing workspace and connect them to the circuit. As a result, after the completed actions, the hierarchical block of the main circuit will contain the number of pins corresponding to the number of added IS/PS connectors in the hierarchical block circuit.
When designing large projects, it may be necessary to replace a group of components on a diagram with a hierarchical block. To do this, you need to select the necessary components in the project workspace using the mouse and select the “Replace with hierarchical block” item in the “Insert” menu. As a result, the “New hierarchical block” window will open, in which you need to select a location on the computer disk in the “Hierarchical block file” field using the “View…” button and specify the name of the new hierarchical block diagram file. After completing the actions, the created hierarchical block will be attached to the mouse cursor. In order to place it in the project workspace, left-click in the required place on the drawing - the connection to the circuit will occur automatically. Figure 4 (a, b) shows the main diagram of the project before and after replacing a group of components on the diagram with a hierarchical block.
Rice. 4. The main diagram of the project before and after replacing a group of components on the diagram with a hierarchical block.
In order to add a subcircuit to the diagram being developed, you must select the “New subcircuit” item in the “Insert” menu. As a result, the “Subcircuit Name” window will open, in which you must specify the name of the new subcircuit and click on the “OK” button. After this, the dialog box will be closed, and the created subcircuit block will be attached to the mouse cursor, which can be placed on the drawing by clicking in the required place with the left mouse button. The name of the new subcircuit appears in the Project Tree on the Structure tab of the Design Panel. Select the line with the name using the left mouse button in order to go to the diagram sheet of the newly created subcircuit. You can also go to the diagram sheet in another way:
Just like the hierarchical block diagram sheet, the newly created subcircuit diagram sheet is a regular Multisim circuit design sheet. Now that you are in the working field of the subcircuit diagram, all that remains is to create the necessary node and connect its pins to the contacts connecting the subcircuit block to the main circuit. Connecting contacts are added manually to the subcircuit diagram. To do this, being on the subcircuit diagram sheet, in the “Insert/Connector” menu, select the “Output hierarchical block/subcircuit” item. Add the required number of connectors to the drawing workspace and connect them to the designed node. As a result, after the completed actions, the subcircuit block located in the main circuit will contain the number of pins corresponding to the number of added IS/PS connectors in the subcircuit circuit. Now the designer can only connect these pins to the main circuit circuit.
When designing large projects, it may be necessary to replace a group of components on a diagram with a subcircuit. To do this, you need to select the necessary components in the project workspace using the mouse and select the “Replace with subcircuit” item in the “Insert” menu. As a result, the “Subcircuit Name” window will open, in which you need to specify the name of the new subcircuit and click on the “OK” button. After completing the actions, the created subcircuit block will be attached to the mouse cursor. In order to place it in the project workspace, left-click in the required place on the drawing - the connection to the circuit will occur automatically. Figure 5 (a, b) shows the main diagram of the project before and after replacing groups of components on the diagram with subcircuits podsxema1 and podsxema2. Figure 6 shows the schematic sheets of the subcircuits podsxema1 and podsxema2.
Rice. 5. The main diagram of the project before and after replacing groups of components on the diagram with subcircuits.
Rice. 6. Sheets of diagrams of subcircuits podsxema1 and podsxema2.
