Circuit Simulation - Engineering - ثاني ثانوي

Lesson 2 Circuit Simulation Electronic circuits are hardware projects which exist in the physical domain, but this also means that malfunctions may occur that are not related to the design of the circuit but are caused by faulty conductors, power sources, etc. This means that you cannot focus on the circuit design alone. For this reason, circuit simulation software can be very helpful and is used by professionals. These programs allow an engineer to design circuits in a controlled environment. When the desired circuit design has been achieved, the engineer then proceeds to build it in the physical domain. In this lesson, you will use Multisim Live to design and simulate electrical circuits. What is Multisim Live? Multisim live allows you to simulate electrical circuits and schematics built on the SPICE simulation architecture. Multisim Live allows you to simulate electronic circuits on any device which has access to a web browser. وزارة التعليم Ministry of Education 2024-1446 Multisim Live FEATURES PRICING CIRCUITS RESOURCES LOG IN SIGNUP Discover Electronics with Online SPICE Simulation SIGN UP FOR FREE SEE HOW IT WORKS FEATURED CIRCUITS Figure 2.7: Multisim Live circuit simulator Link to digital lesson www.ien.edu.sa 43

Create an Account Go to https://www.multisim.com to access Multisim Live. The first thing you need to do is to create an account so you can save your projects. This is simple: click on sign up and fill in the necessary fields. After you have created your account, go back to https://www.multisim.com, then click Log in. When you are logged into an account, the name you have chosen will be displayed here. Multisim Live FEATURES PRICING CIRCUITS RESOURCES HELLO BINARY ACADEMY CREATE CIRCUIT My Circuits CIRCUITS RESOUR My Circuits My Favorites My Groups وزارة التعليم Ministry of Education 44 2024-1446 Public Circuits Reference Circuits Groups Figure 2.8: Create an account My Favorites My Groups Public Circuits Reference Cirsults Groups Discover Electronics with Online SPICE Simulation SEE HOW IT WORKS Click to create a new circuit. 0 When you login to your account, you have access to previous circuits that you have designed, favorite projects shared by other people and community groups which you have joined. FEATURED C You can access these options without being logged into an account. From here you can find circuits designed by others and community groups to join.

Design a Circuit Let's see how we can use Multisim Live to create our first circuit. σ A * HELLO, BINARY ACADEMY CREATE CIRCUIT File navigation menu Click the CREATE CIRCUIT button. Schematic default simulation mode Configuration pane Untitled Circuit Interactive Schematic Grapher Split Stop the simulation Run the simulation This option allows you to view the Schematic and the Grapher simultaneously on one screen. The Grapher is a multi-purpose display tool that allows you to view, adjust, save, and export graphs and charts. Undo, redo, zoom in, zoom out The schematic is where you put components and wire them together, and also add simulation probes. Figure 2.9: Multisim Live user interface The Components toolbar is located on the left side of the screen and provides access to all components. workspace وزارة التعليم Ministry of Education 2024-1446 + ? 45

11 i V وزارة التعليم Ministry of Education 46 2024-1446 Interactive ▼ Schematic Let's have a look at the components toolbar and more specifically, at the categories we will use in this lesson to design circuits. When you add a component to the work space, you have access to the following properties: Flip/Mirror Delete Analysis and annotation Sources C H/P Grapher { ☑ S1 × V1 5V Passive Rotate Duplicate Indicators How to change labels/values of components: ID: V1 Switches HP V1 5V Toggle INFORMATION To change the label on a component, you can click on the label you want to change and then click again to open the ID window. To change the value on a component, you can click on the value you want to change to open the corresponding value window. Change ID of a component Change value of a component H/P V1 10V V1 Voltage: 10 +/- x10 x0.1 Figure 2.10: Multisim Live toolbox

Now you will design your first circuit in Multisim Live. First you are going to connect a resistor of 1kQ. To connect a resistor: > Go to https://www.multisim.com/ and click CREATE CIRCUIT. 11 > On the Components toolbar click the Passive tab. 2 3 > Drag and drop a Resistor into the work space. 4 1 HELLO, BINARY ACADEMY CREATE CIRCUIT V | Interactive▾ * Untitled Circuit Schematic Grapher Split 4 -> R1 www 1kQ X 2 Passive 3 HT m Resistor Capacitor Inductor Potent- iometer Fuse Trans- formers... { Coupled Inductors Resistors... وزارة التعليم Ministry of Education 2024-1446 Figure 2.11: Connect a resistor 47

Next you are going to connect the source. To connect the source: > On the Components toolbar click the Sources tab. > Drag and drop DC Voltage (VCC) into the work 1 a 3 space. * Untitled Circuit i Interactive ▾ Schematic + w t Sources © ④ 2 Grapher \ Split R1 1112 1kQ AC Voltage AC Current Clock Voltage Clock Current Triangular Triangular Voltage Current 2 HilH Φ © ④ 0 O DC Voltage DC Current Step Voltage Step Current AM Voltage FM Voltage (VCC) FM Current Chirp Voltage Chirp Current Thermal Noise Three Phase Three Phase Delta Wye وزارة التعليم Ministry of Education 48 2024-1446 3 HIT V1 Figure 2.12: Connect the source

Now that you have placed the resistor and source in your work space, you need to connect them using a wire. To make connections: > Click on the Source positive upper node and then on the Resistor left node. ② > Click on Resistor right node 3 and then on Source negative lower node. 4 A branch of the circuit is a section of a loop in which there is no node present. You can click on a wire and move it to stretch it or shrink it to get the best result. وزارة التعليم Ministry of Education 2024-1446 1 V1 T 5V V1 4 T5V <- 1 --> 2 R1 ΙΚΩ Node 1 R1 www 3 1ΚΩ Figure 2.13: Make connections 49

The design part is almost finished. The last thing we need to do is to add probes so you can see the measurements on the circuit. To add a Current probe: > On the Components toolbar click the Analysis and annotation tab. 1 > Drag and drop Current probe in series with the Resistor. 3 When we connect a Current probe with its arrow pointing from the negative end (-) to the positive end (+) of the power source, then the value of the current will be negative. Split Item Document * ID PR1 Type Probe PR1X Probe type [?] i Interactive Schem AL 1 a Analysis and annotation وزارة التعليم Ministry of Education 50 2024-1446 Function Flip current measurement Measurement labels ▸ Grapher plot V A 2 V/A Abc 0/1 Voltage Current Voltage and Current Voltage Text Digital Reference Annotation PR X R1 3 A 1 w 4 1ΚΩ V1 2 Current Figure 2.14: Add a Current probe 5V When you see the current values in the ammeters are negative, this means that they are connected opposite to the current flow. We can change the current flow by selecting the current probe, going to the configuration pane, and clicking "Flip current measurement".

You can also add probes to see voltage measurements. To add a Voltage probe: > On the Components toolbar, click the Analysis and annotation tab. > Drag and drop a Voltage probe on the left side of the Resistor. 3 > Click to add a reference probe, 4 and drop it on the right side of the Resistor. 5 i Interactive Schematic a 1 ✔ + Analysis and annotation * Untitled Circuit Grapher \Split V 2 A VIA Abc 0/1 Voltage Current Voltage and Current Voltage Text Digital Reference Annotation وزارة التعليم Ministry of Education 2024-1446 3 PR1 PR R1 A ww V- ΚΩ 4 T 55. V1 5V 2 continues on the next page 51

PR1 A V PR2 V-R1 ww 1ΚΩ V1 5V 2 5 It's important to name the components and detectors you have in your circuit. Figure 2.15: Add a Voltage probe To name the components and detectors: > Click on Source V1 to select it. 1 > Click again on Source V1 to open the ID: box. 2 > Change name to V. 3 PR1 REF1- A V 2 3 ID: V1 V1 1 5V وزارة التعليم 52 Ministry of Education ZU24-1446 PR2+ V-R1 w 1ΚΩ REF1 V 2 This probe is used like a voltmeter in parallel.

Your circuit should now look like the image below.. A i- V1+ REF1- V 1 V-R w 1ΚΩ REF1 V وزارة التعليم Ministry of Education 2024-1446 V 5V 2 Figure 2.16: Name the components and detectors Avoid placing your circuit in an environment where there are liquids, humidity, or dust in proximity. These environmental factors can cause short-circuits that can lead to accidents. Figure 2.17: Example of actual circuit connections 10 53

Now we are ready to run the simulation and see the measurements from the probes. To run simulation: > Click on Run simulation and run the simulation for a short time. 1 > Click to Stop/reset simulation. 2 Errors and Warnings ΙΔΟ a 1 2 Interactive▾ * Untitled Circuit {} >! || ☐ 985.88ms [?] Interactive 2022-05-08 12:37:21 Description No ground node was found in... Type A In the design of simple DC circuits, grounding is not required, so we can ignore this message. > Schematic Grapher V1+ REF1 REF1- i 5.0000mA v 5.0000V A V ww 1ΚΩ 5V 2 Figure 2.18: Run simulation Now that we have designed the circuit with specific the values for the source and the resistor, we can check with Ohm's law: وزارة التعليم Ministry of Education 54 2024-1446 5V 5 Resulting to 5mA = = ⇒ 5 × 10-3 = 1ΚΩ 103 The simulation follows Ohm's law verified by the values displayed by the measurement instruments.

You can save your project to use it again later. To save project: > Click on the File navigation menu. 1 > Click on Save. 2 > In the Save Circuit window, change the name to Ohm's law. 3 > Click OK. 4 1 *Untitled Circuit Schematic Grapher Split New file 2 Save Save as... Untitled Circuit Stream to... Export > V1+ Save Circuit -> Go to > 5.0000mA REFI v 5.0000 www Circuit Details [?] 1kQ Visibility 1-4 Multisim Live وزارة التعليم Ministry of Education 2024-1446 T 5V Private Public 5.000 Name Ohm's law 3 2 Description 1ks add a tag 4 OK Cancel Figure 2.19: Save project 55

To check previous circuits that you have designed, you can go to My Circuits. To open project: > Click on the File navigation menu. > Click on Go to. 2 > Click on My Circuits. 3 1 After you have saved your project, the name changes here. # 1 Ohm's law Schematic Grapher New file \ Split www Save Save as... Stream to... Click New file to start a new project Export 2 3 REF1 Go to > My Circuits Public Circuits Multisim Live Circuit details وزارة التعليم Ministry of Education 56 2024-1446 Multisim Live FEATURES PRICING CIRCUITS RESOURCES HELLO BINARY ACADEMY CREATE CIRCUIT My Circuits MOST POPULAR TAGS Search resistors digital decuit fundamentals systems 4-bit act sweep inductors thyristor rectifiers power supply capacitors ac decuits triac diodes comparator common emitter bode daclade buck amplifier basic concepts byt opama fundamentals Popularity All Circuits Ohm's law by Binary Academy The projects that you have saved are all located here. Figure 2.20: Open project SEARCH FEATURED

Example 1: Series Connection In a circuit with connections that are all in series as shown in the example, we observe that: Example V1+ V2+ 11 REF1 REF2 12 REF1- REF2- V R1 R2 V V V 1 ww 2 w Example V 5V 1ΚΩ 3 4ΚΩ V1+ V2+ 11 REF1 REF1 REF2- i 1.0000mA v 1.0000V 1 v 4.0000V A V V V REF2 V 12 i 1.0000mA 1 ww 1ΚΩ 2 w 4ΚΩ V 5V V₁ = V₁ + V₂ Resulting in 5V = 1V+4V وزارة التعليم Ministry of Education 2024-1446 3 The values displayed by the measurement instruments verify the result. We also note that our ammeters display the same current intensity: I = 1mA 57

Example 2: Parallel Connection In a circuit with connections that are in parallel as shown in the example, we observe that: Example Example A V 18V A V1+ 11 REF1 REF1- V R2 A V 2 w 13 V2+ 6kQ 12 1 REF2 REF2- V R1 V ww 3ΚΩ V1+ 11 A REF1 i 3.0000mA EF1- V v 18.000V 2 w 13 i 9.0000mA V2+ 6kQ i 9.0000mA A 12 REF2 EF2 i 6.0000mA v 18.000V V ww 3ΚΩ V 18V V₁ = V₁ = V₂ = 18V وزارة التعليم Ministry of Education 58 2024-1446 V2 I₁ = I₁ + I2 = I3 ⇒ 9mA = 3mA + 6mA = 9mA

Exercises 1 Design the circuit below: A V 12V S www 2 12V 3 1. Run the simulation and after you close the switch S, write down what you observe. 2. Connect an ammeter to the circuit and write down the value it displays. 3. Change the voltage value of the source to 5V and then to 1V. What do you notice in each case? 4. Change the value of the voltage of the source to 15V, and then to 20V. What do you notice in each case? وزارة التعليم Ministry of Education 2024-1446 59

2 Design the following circuit: وزارة التعليم Ministry of Education 60 2024-1446 Observe and write down the values on the instruments in the table below. A 2 R1 Measuring instrument Value 1ΚΩ Ammeter V1 1 Voltmeter V1+ 10V REF1- V- V R2 3 1ΚΩ REF1 V What do you notice about the voltage across R₂? Explain your answer.

3 Design the following circuit: Set lamps X1 and X2 to have 10V normal operating voltage. X1 1 X2 10V Hi|H 3 S 2 11.0000A A Run the simulation and write down what you notice about the two light bulbs. Explain your observation. Now close the switch S. What do you notice about the light bulbs and the ammeter? Explain your observation. وزارة التعليم Ministry of Education 2024-1446 61