Smart Light Lab - Procedure

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ENGR 1181 Lab 4: Smart Light Lab Procedure ENGR 1181 | Lab 4: Smart Light -Lab Procedure - Worksheet Guidelines

ENGR 1181 Lab 4: Smart Light Lab Procedure Lab Procedure

ENGR 1181 Lab 4: Smart Light Lab Procedure Introduction and Background Objective: Simulate, build, and test the smart-light circuit described in the Preparation Material. Make sure you have gone through the Preparation Material and have completed and submitted the Pre-Lab Quiz. The fundamental concepts covered therein are needed for successfully completing this Lab. The platform for conducting the simulation portion of this lab is called Tinkercad, a modeling program that allows design of different scenarios. Under the circuit category, students can place electric components into a breadboard and make connections between elements in the same way that would be done in the physical lab. Once the circuit is built and the simulation is started, the components behave as in reality – for example, if the current through an LED is too high, you will see it burn! The step-by-step procedure for getting started in Tinkercad and simulating the smart light circuit is described and illustrated in this document. Important: Tinkercad does not support the Circuits mode in tablets. You will need a laptop or desktop for conducting the simulation portion of this lab.

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ENGR 1181 Lab 4: Smart Light Lab Procedure Getting Started in Tinkercad 1. Using a laptop or desktop (not a tablet) access tinkercad.com and click on “Start Tinkering”. 2. Create an account using your email (no need to select join a class). Make sure to use your buckeyemail address. 3. Click on the Tinkercad logo in the top left corner to access your Tinkercad Dashboard. 4. Click on Circuits on the left side Tab. 5. Click on Create new Circuit. 6. Assure you have all components selected to start building your circuit (Figure 1). The step- by-step process for creating the smart-light circuit is in the Procedure document. Figure 1: Components View in Tinkercad that can used to locate the necessary components for the smart-light circuit. Smart Light Lab Setup The circuit diagram for the smart-light system is illustrated in Figure 2. In part 1 below you will find all the steps needed to simulate this circuit using Tinkercad. In part 2, you will find repeat the process to build it with physical components.

ENGR 1181 Lab 4: Smart Light Lab Procedure Figure 2: Circuit schematics of the smart-light sensor system. Step-by-Step Procedure – Part 1: Tinkercad Simulation 1. Breadboard: Search for breadboard and select the “Breadboard Small” component . Drag and place the breadboard in the working area. Rotate the component using the button located in the top left corner, so it is vertical as in Figure 3. Figure 3: Inserting a breadboard. 2. Connect the buses: Remember that in a breadboard all the holes in the columns labeled +/- have the same potential. It will be handy to have positive and negative buses on both sides of the breadboard, so we’ll also connect them with wire. Red is positive and black is negative. Later, once we are done with all the connections, we will connect the power supply – it’s not safe to wire a circuit with power on! To connect a bus to another, simply click on one of the

ENGR 1181 Lab 4: Smart Light Lab Procedure holes and drag the wire until another one and click on it. After they are connected you can edit the color. Figure 4: Connecting postive and negative buses in the breadbord. 3. 10k Ω resistor : Now we will add the 10k Ω resistor, highlighted in Figure 5. Select and drag the resistor into the breadboard. Place it between points 4d and 8d. Then, change the resistance value to 10kΩ , as illustrated in Figure 6. Figure 5: Smart-light circuit schematics.

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ENGR 1181 Lab 4: Smart Light Lab Procedure Figure 6: Adding a resistor. As seen in the schematic, this resistor is connected between the positive voltage of the battery (9V) and the LDR. For neatness, we will not connect them directly, rather use intermediate holes in the breadboard. Hovering your mouse over one hole will show which are interconnected. You can check the connection of the resistor by hovering over any hole in columns a-e in row 4. This is shown below in Figure 7 (a). The interconnected points are considered the same point, therefore connecting point 4d to the positive terminal is equivalent to connecting any other points in the positive column. For neatness, we connected 4a to the positive terminal, as shown in Figure 7(b). The other terminal of the resistor will be the point of connection with the LDR, as described in the next item.

ENGR 1181 Lab 4: Smart Light Lab Procedure Figure 7: Connecting the resistor. 4. LDR : Now, we need to connect the LDR between the 10k resistor and the negative terminal of the battery as shown in Figure 8. Figure 8: Smart-light circuit schematics. Select the component named photoresistor and drag it into the working area. Rotate it and connect one of the terminals to the same point as the resistor (8d); i.e you can select any (a) (b)

ENGR 1181 Lab 4: Smart Light Lab Procedure point in line 8, for example 8e as in Figure 9(a). Then, connect the other terminal to the negative terminal – see Figure 9(b). Figure 9: Inserting the LDR. 5. Potentiometer: The next component to be inserted is the potentiometer. In Figure 10, the potentiometer is connected to the positive and negative terminals of the battery, and the wiper is the negative input of the op-amp. Figure 10: Smart-light circuit schematics. (a) (b)

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ENGR 1181 Lab 4: Smart Light Lab Procedure Search for ‘potentiometer’ in the components tab, drag it to the working area and change its resistance value to 10kΩ. Then, rotate it and connect it in the breadboard as in Figure 11(a). Hover over the terminals and see the labels, Terminal 1, Terminal 2 and Wiper. Connect Terminals 1 and 2 to positive and ground, respectively. The wiper will be connected to one the inputs of the comparator, which is the next stage. Before moving on. Move the wiper to face to the right and leave it there for the rest of the circuit build . Figure 11: Inserting the potentiometer. 6. The next step is to connect the op amp, which acts as the comparator and is highlighted in Figure 12. Figure 12: Smart-light circuit schematics. (a) (b)

ENGR 1181 Lab 4: Smart Light Lab Procedure Search for “operational” and drag the “741 Operational Amplifier” component to the working area. Rotate it and place in the middle of the breadboard, as illustrated in Figure 14 (make sure to place the white dot up!). Hover over the legs of the op-amp to see what each one represents, summarized in Figure 14. Figure 13: Inserting the op-amp. Figure 14: Configuration of the op-amp chip. Dot up Negative Input Positive Input Ground Ground Positive Input Negative Input +9V +9V Output Output

ENGR 1181 Lab 4: Smart Light Lab Procedure First, connect the fourth terminal on the left side, labeled “Power - “ to ground, i.e the negative terminal of the battery (any hole in the column labeled - ). Then, connect the “Power+”, which is the second port on the right side to the positive terminal of the battery, 9V. As seen in Figure 12, the negative input to the op-amp is the potentiometer --- therefore we need to connect the wiper to the second port on the left side of the op-amp. Similarly, the positive input of the op-amp (third port on the left side) is the voltage across the LDR. Those connections are illustrated in Figure 15. Notice that there are three ports that are not used. Note: To make the circuit more organized you can make bends in the wire, as shown in Figure 15b. First start a wire as usual by selecting a hole in the breadboard. Then, chose the section of the breadboard where you want to make the bend (make sure to not select a hole), and then continue to make the wire as normal. You can add as many bends as you want, and can adjust them after the wire is complete. Figure 15: Connecting the op-amp. 7. LED circuit: The last step is to connect the LED and the resistor at the output of the comparator. Power + Power - (a) (b)

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ENGR 1181 Lab 4: Smart Light Lab Procedure Figure 16: Smart-light circuit diagram. Drag the resistor and change the value to 330 Ω (remember to change th e units), as in Figure 17 . Figure 17: Adding a resistor to the circuit. Connect one of the terminals of the 330Ω resistor to the output of the op-amp, which is 3 rd hole on right side (make sure to hover over and confirm that it is Out!). The other terminal can be connected to any other hole that is not being used, as shown in Figure 18 .

ENGR 1181 Lab 4: Smart Light Lab Procedure Figure 18: Connecting the resistor to the output of the op-amp. Finally, select the LED component. Notice that t he LED has a shorter and a longer lead, as shown in Figure 19. The positive terminal of the LED should be connected to the resistor and the negative terminal is wired to the negative bus. Figure 19 illustrates the details of the LED and the circuit after it is inserted. Figure 19: Polarity of and inserting the LED. Longer lead Shorter lead

ENGR 1181 Lab 4: Smart Light Lab Procedure 8. Testing the circuit: Now you are ready to test the circuit! At this point, since the circuit is all connected it’s safe to plug in the power supply . Search for battery and select the 9V battery. Connect its positive terminal to the + column and the negative terminal to the – column, as in Figure 20. Figure 20: Complete smart-light system circuit connected to battery. Your smart-light circuit is complete and ready to be simulated. Press the start simulation button and rotate the knob of the potentiometer to see the LED light up. You can also change the lighting by clicking on the LDR and dragging the button for a dark or well lighted room, as in Figure 21.

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ENGR 1181 Lab 4: Smart Light Lab Procedure Figure 21: Editing the light configurations. Play around with the setting of the potentiometer and the LDR and identify scenarios when the LED is on and off. For example, if there is plenty of light in the room, is there any setting of the potentiometer that would still enable the LED to turn on? 9. Measurements: Download the ‘ Circuits Lab Individual Worksheet ’ on Carmen. You are being asked to present screenshots of your circuit in two scenarios: when the LED is on and off. For each situation, you are to measure the voltages in different points of the circuit. As explained in the Preparation Material, a digital multimeter is a device that can measure voltage and resistance. Tinkercad has a component named “Multimeter” that simulates that device. Below are some examples of measurements:

ENGR 1181 Lab 4: Smart Light Lab Procedure Example 1 - Measuring the voltage from the power supply. Voltage is always measured across two points, in this case the positive and negative terminals of the battery. Since they are connected to the +/- columns in the breadboard, we can connect the terminals of the multimeter to any of those points, as shown in Figure 22. Figure 22: Measuring the voltage of the battery. Example 2 - Measuring the voltage across a resistor. To measure how much voltage is across an element, for example the 10k Ω resistor, simply connect the terminals of the multimeter to the terminals of the resistor. See Figure 23. Figure 23: Measuring the voltage across a resistor.

ENGR 1181 Lab 4: Smart Light Lab Procedure Example 3 - Measuring voltage at a certain node in the breadboard. Since voltage is measured in terms of potential difference between two points, for this case we need to connect one of the terminals of the multimeter at the point and the other at the reference voltage (ground). For example, if we want to measure the voltage at the negative input of the op-amp, we should connect the multimeter as illustrated in Figure 24. Figure 24: Measuring voltage at negative input of the op-amp. You can also measure several different voltages in the circuit at the same time, by adding extra multimeters. This allows and easy understanding of the op-amp acting as a comparator. Figure 25 illustrates a scenario where the LED is on and both inputs as well as the output of the op-amp is being measured. Notice that in this configuration, the light sensor and the potentiometer are set to their minimum. Try to simulate the same and then play around with your circuit to make sure it is behaving correctly, correctly meaning an increase in room light turns the LED off. Figure 25: Measuring different voltage levels in the circuit.

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ENGR 1181 Lab 4: Smart Light Lab Procedure Part 2: Building the Circuit Before you start, confirm that you have all the components shown in Table 1. If you are missing anything, let your TA know. Table 1: Smart-light circuit components. Component Photo LED Op amp Light Sensor 330 Ω resistor (orange, orange, brown, gold) 10 kΩ resistor (brown, black, orange, gold) Potentiometer Power Supply With Banana Cables Wires Multimeter

ENGR 1181 Lab 4: Smart Light Lab Procedure 1. Connect the buses: When working with a breadboard, the power supply will connect to the breadboard via banana clips. The positive and negative buses need to be connected to the banana clip terminals. If they are not already connected, connect the positive bus to the red terminal and the negative bus to the black terminal. Connect the bus lines on either side of the bread board together, positive to positive, negative to negative. Refer to figure 26 for an example. Figure 26: Positive and negative bus connections on a physical breadboard. 2. Potentiometer: This is one of two components that looks slightly different as physical components than it did in Tinkercad. The potentiometer, shown in Figure 27, still has three terminals: Pin 1 is connected to positive power, Pin 3 is connected to negative power, and Pin 2 is connected to the “ - ” terminal in the comparator. When you insert this component into your circuit, remember to keep the side with two pins to the right. Figure 27: The potentiometer. Pin 2 Pin 1 Pin 3

ENGR 1181 Lab 4: Smart Light Lab Procedure 3. Light sensor: The other different component is the light sensor. It can bee seen in Figure 28. Figure 28: The light sensor. 4. Construct the circuit: Repeat steps 3-7 from Part 1 using physical components. When connecting wires to the breadboard, ensure that at least a quarter inch of exposed, straight wire can be inserted into the board to make a good connection. When connecting the resistors, pay particular attention to the color bands on them as they denote the resistance value, referring to Table 1 as necessary. Also note the polarity of the LED in step 7, as described in Figure 19. 5. Check the circuit: When the circuit is completed, it should look like the one shown in Figure 29. Figure 29: An example completed circuit. 6. Check for a short-circuit: Visually inspect your circuit for any exposed metal contacts touching other components that they would normally not connect to. Set your multimeter to measure resistance by turning the main knob towards the Ohm (Ω) setting. Measure the resistance between the positive power and negative power terminals; the value should not be in the thousands of Ohms (kΩ). If it is not, ask a TA for help. 7. Testing the circuit: Now you are ready to test the physical circuit! At this point, since the circuit is all connected it is safe to plug in the power supply. With the power supply turned off, connect the positive and negative terminals of the power supply to the positive and negative of the breadboard. Make sure your current knob is turned all the way to the left

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ENGR 1181 Lab 4: Smart Light Lab Procedure and then turn on the power supply and adjust the voltage to 9V. Careful: If you cannot adjust the voltage of the power supply to 9V, DO NOT try to change the current (you could blow up the op amp!). Turn off your power supply and have a TA double-check your circuit. Figure 30: Complete smart-light system circuit connected to power supply. 8. Complete question 4 on the Smart Light Lab Individual Worksheet, filling in values for the inputs and output of the op-amp when the LED is both on and off. Remember that the circuit (specifically, the potentiometer) should not change between the on and off conditions – only the light reaching the light sensor should. For best consistency, hold a finger fully against the light sensor when simulating the dark condition. 9. When you have completed all lab activities, turn off your power supply, disconnect it from your circuit and begin disassembly. Clean-Up Procedure Caution: DO NOT Remove the power supply wires from the Breadboard. First make sure to turn off the power supply, then unplug it from the breadboard. Remove all the components from the breadboard and place them back in their respective plastic bags. At the end of the lab, your Breadboards should be exactly like Figure 31:

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ENGR 1181 Lab 4: Smart Light Lab Procedure Figure 31: A breadboard that has been reset at the end of lab. Some models require small jumper wires on the positive and negative power buses to connect the top and bottom halves of the boards. If any components in your kit are damaged, make sure to notify someone in the instructional team so it can be replaced. Check-Out Policy After you have finished the lab and the clean-up procedure, have your instructional team verify your workstation is clean before you leave. Worksheet Guidelines Complete Lab 4 Individual Worksheet Download and complete the Smart Light Lab Individual Worksheet from Carmen. Refer to the worksheet on Carmen for specific instructions. Submit the assignment to Carmen. Note: This is not the same as the pre-lab assignment. For Further Reference Students who enjoy working with circuits of all types could consider further studies in electrical engineering. Those who like the idea of using engineering to improve quality of life could look into human factors in industrial and system engineering. Studies in both food, agricultural, and biological engineering (FABE) and also civil engineering often have interesting applications of smart systems.

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ENGR 1181 Lab 4: Smart Light Lab Procedure Semester Map: Lab 1 – Buckeye Challenge – Team building through tower building Pre-work – None Output – Team Introductions Worksheet and Photo; Draft team working agreement Lab 2 – Technical Communications – Discover the value of clarity and concision Pre-work – Review Challenger case study Output – Teamwork – Email rewrite; List of audience-specific changes; Jigsaw Lab 3 – Spot Speed Study – Gather real-world speed trap data for public safety Pre-work – Plan group communication Output – Individual Work – Professional Email (not sent) Lab 4 – Smart Light – Simulate and construct smart circuitry Pre-work – Reading and quiz – Basic circuit components and simulation Output – Individual work – Summary worksheet; Update team working agreement Lab 5 – Beam Bending – Investigate fundamental properties to identify the use of metals Pre-work – Reading - Review pre-lab materials and procedure Output – Teamwork – Lab Memo Lab 6 – Humanitarian Relief – Coordinate supply logistics for earthquake victims Pre-work – Reading – Worksheet with questions on videos, lab documents, and roles Output – Teamwork – Executive Summary Lab 7 – Artificial Muscle – Manufacture and test real artificial muscles Pre-work – Reading - Review pre-lab materials and procedure Output – Individual work - Worksheet Lab 8 – Wind Turbine – Develop and evaluate wind turbines to power a town. Pre-work – Individual worksheet – Derivation, Article review, blade design Output – Teamwork – Lab Report Lab 9 – Software Design Project Output – Teamwork – Custom Video Games; Website

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Smart Light Lab - Procedure

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