Practical lessons
General information about Multisim
Multisim is version 6.02 (version 10 appeared in 2007) of the Electronics Workbench (EWB) program developed by Interactive Image Technologies. A feature of the program is the presence of a control measuring instruments, extensive libraries electronic components, including logic chips small and medium degree of integration.
The program allows you to simulate logical devices, typing them from separate components, analyze the behavior of the circuit under various influences on the arguments, carry out "reconstruction", replacing some elements with others. At the same time, material resources spent on laboratory equipment and its maintenance are saved, and the risk of “burning out” elements that occurs when debugging real circuits disappears.
Let's get acquainted with the element base and analysis instruments used in this work.
Logical elements are called from the MISC library by successively pressing the left mouse button on the symbols:
The MISC library is widely represented by two and multi-input logic elements AND (AND)-U1, OR (OR)-U2, NOT (NOT)-U3, AND-NOT (NAND)-U4, OR-NOT (NOR)-U5, M2 (EOR)-U6, M2 with inversion (ENOR)-U7,
AND-OR-NOT (AND-OR-N)-U8:
In addition to the presented logical elements, passive elements-resistors and resistor assemblies, switching facilities-switches and buttons, power supplies will be required. All these elements and tools can be extracted from the corresponding sections of the libraries:
Schema input arguments can be managed both manually and automatic modes. Manual control, i.e. the supply of logical zeros and ones is carried out using contact switches, and automatically using the generator of logical signals Word Generator.
The generator can output 32-bit binary words, and code combinations must be specified in hexadecimal code.
Each code combination is entered using the keyboard, the number of the edited cell is recorded in the EDIT box of the ADRESS block. During the operation of the generator in the ADRESS compartment, the number of the current CURRENT cell, the initialization cell or the start of work INITIAL and the final cell FINAL are displayed. Additional controls include buttons CYCLE - cyclic mode starting from the zero cell, BURST - from the selected word to the end, STEP - step-by-step mode, BREAKPOINT - interrupting the generator in the specified cell.
To transfer a component from the library to the workspace, the mouse cursor is moved to the icon of the corresponding section, and its name is highlighted. After selecting the component with the mouse cursor and pressing its left button (cancel the selection - click right button) There are two possibilities. In the first, most simple case, the mouse cursor in the form of an arrow with the selected component is transferred to the working field and pressed left button mice. In the second case, the call of the component is accompanied by a call to the window. If it is necessary to edit the parameters of the component, then the Edit button is pressed in this window, the parameters are corrected, and only after pressing the OK button in this window the mouse cursor takes the specified form.
The connection of the conclusions of all elements with each other is carried out only by wires. It is not allowed to overlap the conclusions of the elements on each other - in this case, the connection is not established. To lay connecting conductors, move the mouse cursor to the component pin and when the cursor takes on a cross shape, press and release the left mouse button, drag the conductor in the form of a dotted line to the second component pin and press and release the left mouse button again. To delete a conductor, it is selected and the Delete key is pressed. When changing the shape of the conductor, it is marked, while the points of its inflections and connections with the pins of the component are marked with squares, which serve to move its individual parts with the mouse cursor.
When you place the mouse cursor on the device icon or on any other circuit component and press its right button, a dynamic menu is called up that allows you to cut (Gut), copy (Copy), change the color (Color) of the component, and also execute four commands to move it ( rotation).
If you need to delete, copy, change color or move a component, it is advisable to use the appropriate commands from the Edit menu. If it is required to reproduce a certain component, then after copying it, the mouse cursor is placed on the free space of the working field and by pressing the right mouse button, the second dynamic menu is called up, which differs from the first a large number commands. After selecting the Paste command from this menu, the mouse cursor with the component icon attached to it is placed in the desired location of the future circuit and the left mouse button is pressed. If the component needs to be inserted into a conductor gap, then it is installed so that its pins on both sides coincide with the conductor, after which the left mouse button is pressed. To delete a component, it is marked and the Delite key is pressed, and the conductors attached to it are also deleted.
In connection with the wide development of computing devices, the problem of calculation and modeling electrical circuits noticeably simplified. most suitable software for these purposes is the product National instruments - Multisim (Electronic Workbench).
In this article, we will consider the simplest examples of modeling electrical circuits using Multisim.
So, we have Multisim 12 that is latest version at the time of writing. Open the program and create new file using the Ctrl+N shortcut.
After creating the file, a working area opens in front of us. In fact, the Multisim workspace is a field for collecting the required circuit from the available elements, and their choice, believe me, 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.
By default, the item 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, ground.
Basic - resistors, capacitors, inductors, etc.
Diodes - contains different kinds diodes.
Transistors - contains various types of transistors.
Analog - contains all kinds of amplifiers: operational, differential, inverting, etc.
TTL - contains elements of transistor-transistor logic
CMOS - contains elements of CMOS logic.
MCU Module is a multipoint communication control module.
Advanced_Peripherals - connected external devices.
Misc Digital - various digital devices.
Mixed - combined components
Indicators - contains measuring devices, etc.
With the modeling panel, too, nothing complicated, as on any reproducing device, the start, pause, stop buttons are shown. The remaining buttons are needed for step-by-step modeling.
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, desktop 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 source direct current(dc-power) and a pair of resistors (resistor).
Let's say we need to determine the current in the unbranched part, the voltage across the first resistor, and the power across the second resistor. For these purposes, we need two multimeters and a wattmeter. We switch the first multimeter to the ammeter mode, the second - to the voltmeter, both to constant voltage. We connect the current winding of the wattmeter to the second branch in series, the voltage winding is parallel to the second resistor.
There is one feature of modeling in Multisim - the circuit must have grounding, so we will ground one pole of the source.
After the circuit is assembled, click on the start of the simulation and look at the instrument readings.
Let's check the correctness of the readings (just in case =)) according to Ohm's law
The readings of the instruments turned out to be correct, we proceed to the next example.
Example 2
Let's assemble an amplifier on a bipolar transistor according to a circuit with a common emitter. As a source input signal use a function generator. In the FG settings, we select a sinusoidal signal with an amplitude of 0.1 V, a frequency of 18.2 kHz.
With the help of an oscilloscope (oscilloscope) we will remove the waveforms of the input and output signals, for this we need to use both channels.
To check the correctness of the oscilloscope readings, we put the input and output on the multimeter, switching them first to the voltmeter mode.
We start the scheme and open double click every appliance.
The readings of the voltmeters coincide with the readings of the oscilloscope, if you know that the voltmeter shows the effective value of the voltage, to obtain which it is necessary to divide the amplitude value by the root of two.
Example 3
Using logic elements 2 AND-NOT, we will assemble a multivibrator that creates rectangular pulses of the required frequency. To measure the frequency of the pulses, we use a frequency counter, and check its readings with an oscilloscope.
So, let's say we set a frequency of 5 kHz, empirically selected the required values \u200b\u200bof the capacitor and resistors. We run the circuit and check that the frequency counter shows approximately 5 kHz. On the oscillogram, we mark the period of the pulse, which in our case is 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 activity etc.
We hope this article was useful to you. Thank you for your attention!
In connection with the wide development of computing devices, the task of calculating and modeling electrical circuits has been noticeably simplified. The most suitable software for this purpose is the National instruments product - Multisim (Electronic Workbench).
In this article, we will consider 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, a working area opens in front of us. In fact, the Multisim workspace is a field for collecting the required circuit from the available elements, and their choice, believe me, 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.
By default, the item 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, ground.
Basic - resistors, capacitors, inductors, etc.
Diodes - contains various types of diodes.
Transistors - contains various types of transistors.
Analog - contains all kinds of amplifiers: operational, differential, inverting, etc.
TTL - contains elements of transistor-transistor logic
CMOS - contains elements of CMOS logic.
MCU Module is a multipoint communication control module.
Advanced_Peripherals - connected external devices.
Misc Digital - various digital devices.
Mixed - combined components
Indicators - contains measuring devices, etc.
With the modeling panel, too, nothing complicated, as on any reproducing device, the start, pause, stop buttons are shown. The remaining buttons are needed for step-by-step modeling.
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, desktop multimeter.
So, having briefly examined the functionality of the program, let's move on to practice.
Example 1
To begin with, let's assemble a simple circuit, for this we need a constant 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 across the first resistor, and the power across the second resistor. For these purposes, we need two multimeters and a wattmeter. We switch the first multimeter to the ammeter mode, the second - to the voltmeter, both to constant voltage. We connect the current winding of the wattmeter to the second branch in series, the voltage winding is parallel to the second resistor.
There is one feature of modeling in Multisim - the circuit must have grounding, so we will ground one pole of the source.
After the circuit is assembled, click on the start of the simulation and look at the instrument readings.
Let's check the correctness of the readings (just in case =)) according to Ohm's law
The readings of the instruments turned out to be correct, we proceed to the next example.
Example 2
Let's assemble an amplifier on a bipolar transistor according to a circuit with a common emitter. We use a function generator as an input signal source. In the FG settings, we select a sinusoidal signal with an amplitude of 0.1 V, a frequency of 18.2 kHz.
With the help of an oscilloscope (oscilloscope) we will remove the waveforms of the input and output signals, for this we need to use both channels.
To check the correctness of the oscilloscope readings, we put the input and output on the multimeter, switching them first to the voltmeter mode.
We launch the scheme and open each device with a double click.
The readings of the voltmeters coincide with the readings of the oscilloscope, if you know that the voltmeter shows the effective value of the voltage, to obtain which it is necessary to divide the amplitude value by the root of two.
Example 3
Using logic elements 2 AND-NOT, we will assemble a multivibrator that creates rectangular pulses of the required frequency. To measure the frequency of the pulses, we use a frequency counter, and check its readings with an oscilloscope.
So, let's say we set a frequency of 5 kHz, empirically selected the required values \u200b\u200bof the capacitor and resistors. We run the circuit and check that the frequency counter shows approximately 5 kHz. On the oscillogram, we mark the period of the pulse, which in our case is 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 activities, etc.
We hope this article was useful to you. Thank you for your attention!
Faculty of Nonlinear Processes Department of Electronics, Oscillations and Waves
E.N. Egorov, I.S. Rempen
APPLICATION OF THE SOFTWARE APPLIED PACKAGE MULTISIM FOR SIMULATION OF RADIO-PHYSICAL SCHEMES
Teaching aid
Saratov - 2008
Introduction |
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Basic principles for creating a circuit |
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Description of the main elements |
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Circuit Analysis |
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Precautions and safety |
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Theoretical task |
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Task for a numerical experiment |
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Appendix |
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test questions |
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1. Introduction
The development of any electronic device is usually accompanied by
physical or mathematical modeling. Physical modeling is associated with high material costs, since it requires the manufacture of mock-ups and their study, which can be very laborious. Therefore, mathematical modeling is often used using tools and methods computer science. One such program is the electronic simulation system Multisim (Electronics Workbench), which is simple and easy to learn. user interface. Multisim has become widespread in secondary and higher educational institutions, where it is used for educational purposes as a laboratory workshop on a number of subjects (physics, fundamentals of electrical engineering and electronics, fundamentals of computer technology and automation, etc.).
The Multisim electronic simulation system simulates the real workplace researcher - a laboratory equipped with real-time measuring devices. With its help, you can create, model both simple and
and complex analog and digital radio physical devices.
AT This lab describes the basic principles of working with the Multisim 9 electronic simulation system. To clearly understand the principles of its operation, you must:
knowledge of the basic principles of work operating system windows;
understanding of the principles of operation of the main measuring instruments (oscilloscope, multimeter, etc.);
knowledge of individual elements of radio electronic devices.
2. Basic principles for creating a circuit.
Working with the electronic simulation system Multisim includes three main
stages: creating a circuit, selecting and connecting measuring instruments, and, finally, activating the circuit - calculating the processes occurring in the device under study.
In general, the process of creating a circuit begins with placing components from the program library on the Multisim workspace. The subsections of the Multisim program library can be called one by one using the icons located on the toolbar (Fig. 1). The directory of the selected section of the library is located in
vertical window to the right or left of the working field (set to any place by dragging in a standard way- for the header). To select the required element from the library, move the mouse cursor to the corresponding icon and click once on the drop-down list arrow, then select the element required for work in the list. After that, the icon (symbol) of the component necessary for creating the circuit is transferred to the working field of the program by pressing the left mouse button. When placing circuit components on the working area of the program, you can also use the context menu that appears when you right-click on the free space working field. At this stage, it is necessary to provide a place for placing control points and icons of instrumentation.
Rice. 1. Multisim 9 component library directories
The selected schematic component (highlighted by a dashed blue line) can be rotated ( context menu, buttons on the toolbar or menu item Circuit>Rotate) or flip around the vertical (horizontal) axis (menu command Circuit>Flip Vertical (Horizontal), context menu, buttons on the toolbar). When turning, most components are rotated 90o counterclockwise each time a command is executed, for measuring instruments (ammeter, voltmeter, etc.) the connection terminals are reversed.
In the finished circuit, it is not advisable to use rotation and reflection of elements, since this most often leads to confusion of connecting wires - in this case, the component must be disconnected from the circuit, and only then rotated (reflected).
By default, a virtual element is set, which has ideal properties (for example, the absence of internal noise and losses) of one or another element. By double-clicking on a component's icon, you can change its properties. In the drop-down dialog box, the required parameters are set (as a rule, the nominal value of the circuit element and a number of other parameters for other elements such as measuring instruments or complex integrated circuits) and the selection is confirmed by pressing the "Ok" button or the "Enter" key on the keyboard. In the same dialog box, when you click the Replace button, a dialog box appears showing the entire library of elements. Using this window, you can replace an ideal element with its real counterpart, while not only its denomination varies, but also the manufacturer of specific circuit elements, as well as the series of the element. For a large number of components, you can select parameters that correspond to real elements (diodes, transistors, etc.) from different manufacturers.
When creating schemes, it is also convenient to use the dynamic menu, which is called by pressing the right mouse button. The menu contains the commands Help (help), Paste (insert), Zoom In (increase), Zoom Out (reduce), Schematic Options (scheme parameters), as well as the Add commands<Название компонента>. This command allows you to add components to the workspace without accessing the library directories. Number of Add commands<Название компонента>in the menu list is determined by the number of component types (resistors, ground sign, etc.) already present in the workspace.
After the components are placed, their pins are connected with conductors. Note that only one conductor can be connected to a component pin. To make the connection, the mouse cursor is moved to the component pin, and after the pad appears, the left mouse button is pressed. The conductor that appears in this case is pulled to the pin of another component until the same pad appears on it, after which the left mouse button is pressed again. If it is necessary to connect other conductors to these pins, in the context menu (appears when the right mouse button is pressed), a point is selected (connection symbol, denoted as
Junction) and is transferred to the previously installed explorer. If a trace of a crossing conductor is visible on it, then there is no electrical connection and the point must be re-installed. After successful installation, two more conductors can be connected to the connection point. If the connection needs to be broken, the cursor is moved to the corresponding wire and highlighted with the left mouse button, after which the Delete key is pressed.
If it is necessary to connect the output to the conductor present on the circuit, then the conductor from the component output is moved by the cursor to the specified conductor, and after the connection point appears, the left mouse button is pressed. It should be noted that the laying of the connecting conductors is carried out automatically, and the obstacles - components and other conductors - bend around in orthogonal directions (horizontally or vertically).
Connection to the circuit of instrumentation is carried out in a similar way. The panel with control and measuring equipment (with the exception of the ammeter and voltmeter) is located vertically on the right side of the working area, and includes such elements as a multimeter, an oscilloscope (2 and 4 channels), a wattmeter, a function generator, a baudplotter, a spectrum analyzer etc. The operation of some of these devices will be described in more detail below.
For instruments such as an oscilloscope or logic analyzer, it is advisable to make connections with colored conductors, since their color determines the color of the corresponding waveform.
Each element can be moved to a new location. To do this, it must be selected and dragged with the mouse. In this case, the location of the connecting wires will change automatically. You can also move a whole group of elements: to do this, you need to select them sequentially with the mouse while holding down the Ctrl key, and then drag them to a new location. If it is necessary to move a separate segment of the conductor, the cursor is brought to it, the left button is pressed and, after the double cursor appears in the vertical or horizontal plane, the necessary movements are made.
3. Description of the main elements
As already mentioned, in electronic system Multisim has several sections
libraries of components that can be used in modeling. Below is a brief summary of the main (of course, not all) components. After the name in parentheses are some parameters of the component that can be changed by the user.
All components are conditionally divided into a number of subgroups.
3.1. Signal sources(Power Source Components and Signal Source Components tabs).
It is clear that here signal sources mean not only power sources, but also controlled sources.
Battery (voltage). The long strip corresponds to the positive terminal.
Grounding (label). |
DC source |
AC source |
AC source |
sinusoidal voltage |
sinusoidal current |
(effective value |
(effective current value, |
voltage, frequency, phase). |
frequency, phase). |
Sources of fixed |
Unipolar generator |
voltage. Applied in |
rectangular pulses |
logic diagrams. |
(amplitude, frequency, |
fill factor). |
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Amplitude generator |
Phase generator |
modulated oscillations |
modulated oscillations |
(voltage and frequency |
(voltage and frequency |
carrier, ratio and |
carrier, index and frequency |
modulation frequency). |
modulation). |
3.2. Passive elements(Basic tab) - a library that contains all passive components, as well as communication devices.
Resistor (resistance). Capacitor (capacity).
Inductor Transformer. (inductance).
Relay (found only in the element library).
A switch controlled by pressing the specified key (default is space).
Potentiometer (rheostat). The “Key” parameter defines the character of the keyboard key (A by default), when pressed, the resistance decreases by the value specified in percentage (the “Increment” parameter, by default 5%) or increases by the same value when the Shift + “Key” keys are pressed. The "Setting" parameter sets initial installation resistance in percent (default - 50%), the "Resistance" parameter sets the nominal resistance value.
Capacitor and inductor of variable capacity. They work in the same way as a potentiometer.
3.3. Semiconductor elements(Diode Components and Transistor Components) - diodes and transistors.
LED (type).
Symmetrical dinistor or diac (type).
Rectifier bridge (type).
Symmetrical trinistor or triac (type).
Insulated gate MOSFETs (n-channel rich substrate and p-channel depleted substrate), with separate or connected substrate and source leads (type).
Insulated gate MOSFETs (n-channel rich gate and p-channel lean gate), with separate or connected substrate and source leads (type).
Gallium arsenide n- and p-channel FETs(type)
The above sections of the library contain the main circuit elements that students will have to apply in this workshop. Next, we will describe some sections of the library, which in our work will be affected less frequently.
3.5. Logic digital circuits (sections of the TTL and CMOS libraries).
Light indicator (glow color). Seven-segment indicator with a decoder (type). Line of ten LEDs with built-in ADC (minimum and minimum voltage).
EXCLUSIVE OR-NOT (number of inputs)
Tri-stable buffer Schmidt trigger (type) (tri-state element) and buffer (type)
More complex elements of digital circuitry (flip-flops, multiplexers, decoders, etc.) do not have special designations in Multisim and are depicted as an icon (a square with a different number of outputs and corresponding designations). You can determine the type of a particular circuit element by the description in the library window. Therefore, they are not described here.
3.6. Display devices(Misc, Measurement Components or the Indicators section in
library).
Voltmeter with digital readout (internal resistance, constant or alternating current). The negative terminal is shown as a thick black line.
Ammeter with digital reading (internal resistance, DC or AC measurement mode). The negative terminal is shown as a thick black line.
Incandescent lamp (voltage, power). Seven-segment indicator
Line of ten independent LEDs (voltage, nominal and minimum current).
PURPOSE OF THE WORK
Studying and gaining skills in the program Multisim
TASK FOR WORK
Learn the principle of construction electronic circuits in a programme 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 tools used, selected from the Multisim database/
The general development panel shown in Figure 1. contains the circuit window, which contains the circuit under study.
The standard panel contains following buttons:
The toolbar contains the following buttons:
Finally, the components panel shows the following elements:
Instruments
Multisim has a number of VIs. These devices are used in the same way as their real-world equivalents. Using VIs is one of the best and easiest ways to explore a circuit. These fixtures can be placed on any schematic or subcircuit level, but they are only currently active for the schematic or subcircuit on active components.
VIs have two views: an instrument icon, which you place on your schematic, 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 schematic. When a tool is active, a black dot inside the I/O indicators indicates that the tool is linked to a junction point.
Adding a fixture to a schematic:
1. By default, the instrument panel is displayed on the workspace. If the instrument panel is not displayed, click the Instruments button. The Instruments Toolbar appears, with each button corresponding to one instrument.
2. On the Instruments toolbar, click the button for the instrument you want to use.
3. Move the cursor to the place of the scheme where you want to place the device and click 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 fixture you place on the schematic will be named "XMM1", the second fixture will be named "XMM2", and so on.
Note: To change the color of the Instrument icon, right-click on it and select color from the context menu. Choose the color you want and click OK.
Appliance use:
1. Double-click the instrument to view and modify instrument controls. The Tool Control window will appear. Make the necessary changes to the settings just as you would on their real world equivalents.
Please note that the settings must match your schema. If the settings are incorrect, this can skew the simulation results.
Note: Not all areas of an open fixture can be modified. The hand mark appears when the cursor is on a setting that can be changed.
2. To "activate" the circuit, press the Simulate button on the Control Panel, and select Run from the pop-up menu that appears. Multisim will begin simulating the behavior of the circuit and the values of the measured parameters at the points to which you have connected the instrument.
While the outline is active, you can adjust the tool settings, but you cannot change the outline by changing values or by performing any action, such as rotating or moving the element.
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