lab1 (1)-1

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1 Lab 1 EE97 Spring 2024 Thursday 1.30 - 4.15 PM Lab 1: DMM and Breadboard Samal Maleesha Wijendra Partner: John Wu Submission Date:___________________ 02/08/2A

2 Lab 1 Learning objectives After completing this lab, students should be able to • Identify the resistance, tolerance, and wattage of commonly used 1/4W resistors. • Measure resistance, capacitance, and voltage using a digital multimeter (DMM). • Construct simple circuits on a breadboard. This lab also reinforces students’ understanding of voltage, current, Ohm’s law, and the concept of the ideal voltage source Experiment 1 Pickup four random resistors resistance with distinct color bands on them and record their resistance, rated tolerance, power rating, and make calculations to distinguish the actual deviation. Part 1: Randomly select 4 resistors (each with a distinct color code) from the resistor bin and read out the values by their color codes. Resistor Band 1 Band 2 Band 3 Band 4 Resistor Value 1 Yellow 4 Purple 7 Brown 1 Gold 470Ω 2 Grey 8 Red 2 Gold 1 Gold 8.2Ω 3 Brown 1 Black 0 Red 2 Gold 1kΩ 4 Orange 3 Orange 3 Black 0 Gold 33Ω Part 2: What is the rated tolerance of these resistors? 5% Part 3: What is the power rating of these resistors? 0.25w

3 Lab 1 Part 4: Measure and record the resistance of the resistors Resistor Measured Resistance 1 466.24Ω 2 8.097Ω 3 987Ω 4 32.68Ω Part 5: Calculate the actual deviation using the formula. ࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵? − ࠵?࠵?࠵?࠵? ࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵?% = ( ∗ 100%) ࠵?࠵?࠵?࠵? Resistor Calculation Deviation 1 ( |ସ଺଺.ଶିସ଻଴| ସ଻଴ ∗ 100%) 0.8% 2 ( |଼.ଵି଼.ଶ| ଼.ଶ ∗ 100%) 1.22% 3 ( |ଽ଼଻ିଵ଴଴଴| ଵ଴଴଴ ∗ 100%) 1.3% 4 ( |ଷଶ.଺଼ିଷଷ ଷଷ` ∗ 100%) 0.97% Are they within the rated tolerance specified by the color code? Yes, all of them are under the tolerance rate of 5%

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4 Lab 1 Experiment 2 Randomly select 4 capacitors, record their capacitance, and calculate the nominal capacitance. Part 1: Randomly select 4 capacitors from the parts bin, two ceramic and two electrolytic. Read out the values by their marking. Capacitor Reading Capacitance 1 ceramic 104 100nF 2 ceramic 103 10nF 3 electrolytic 470µF 470µF 4 electrolytic 47µF 47µF Part 2: Measure and record the capacitances of the capacitors. Capacitor Capacitance 1 ceramic 101.5nF 2 ceramic 9.64nF 3 electrolytic 426µF 4 electrolytic 44.8µF

5 Lab 1 Part 3: What are the percentages of error of the measured capacitances from their nominal capacitances? (࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵? ࠵?࠵?࠵?࠵?࠵? – nomi value) ࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵?࠵? ࠵?࠵? ࠵?࠵?࠵?࠵?࠵?% = ( ∗ 100%) Nomi value Capacitor Calculation Error % 1 ceramic ( | ଵ଴ଵ .ହ ିଵ଴଴| ଵ଴଴ ∗ 100%) 1.5% 2 ceramic ( | ଽ .଺ସ ିଵ଴| ଵ଴ ∗ 100%) 3.6% 3 electrolytic ( | ସଶ଺ ିସ଻଴| ସ଻଴ ∗ 100%) 9.36% (not optimal) 4 electrolytic ( | ସସ .଼ ିସ଻| ସ଻ ∗ 100%) 4.68% Experiment 3 Check the given picture of the circuits in a breadboard and identify errors without building the circuits physically. Create the given circuit and measure and calculate the resistance, then compare them. Figure 12

6 Lab 1 Part 1: The circuit in Figure 11 is constructed on a breadboard in 4 different ways as shown in Figure 12. Check these circuits to see if they are valid constructions. If not, point out at least one mistake in the construction. Do not build the circuits. Circuit Validation Mistake 1 Good NA 2 Wrong Short circuit between R3 resistor’s connection 3 Wrong Open circuit between R3 and R4 resistors 4 Good NA Part 2: Construct the circuit shown in Figure 11 (use R1=1kΩ, R2=2.2kΩ, R3=4.7kΩ, R4=1.5kΩ and verify their color code) on the breadboard then, using DMM, measure the resistance between points A and B. Calculate the resistance between A and B. Is the measured value close to your calculated value? Sketch your circuit connections on the breadboard. Measurement: 3.36kΩ.

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7 Lab 1 Calculation: Experiment 4 • Calculate the measurements of AA battery circuit and measure their values using DMM Part 1: In Figure 16, assuming the AA battery has exactly 1.5v and the 9v battery has exactly 9v, what is Vca? Part 2: What is VAC , in Figure 17?

8 Lab 1 Part 3: Write down the values VAB, VBC, VA, VB, and VC in Figure 16. V AB V BC V A V B V C Values 1.5v -9v 0 -1.5v 7.5v Part 4: Write down the values VAB, VBC, VAC, VA, VB, and VC in Figure 17. V AB V BC V AC V A V B V C Values -1.5v -9v 10.5v -1.5v 0 9v Part 5: Build the circuit in Figure 16. Measure and record VAB , VBC , VCA , VA , VB , and VC in Figure 16. Some of these six voltages are equivalent so you don’t necessarily need to take 6 measurements separately. V AB V BC V CA V A V B V C Values 1.49v -8.9v 7.39v 0 -1.49v 7.39v

9 Lab 1 Part 6: Repeat steps 5 and 6 above for the circuit in Figure 17. V AB V BC V CA V A V B V C Values -1.49v -8.89v 10.39v -1.49v 0 8.89v Experiment 5 Monitor the voltage of a battery while gradually increasing the load current and make measurements with it. Part 1: Obtain an AA size battery. Before connecting this battery to the circuit, measure its voltage. This voltage is called the "open circuit" voltage Voc. 1.49v Part 2: Construct the circuit shown in Figure 20 on a breadboard with resistance R=1kΩ and measure the voltage across the battery. 1.488v = 1.49v

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10 Lab 1 Part 3: One at a time, replace resistance R with the following resistor values: 470Ω, 100Ω, 47Ω, 22Ω, 11*Ω, 5.5*Ω, and 3.3*Ω. The 11*Ω load should be made with two 22Ω resistors in parallel. The 5.5*Ω load should be made with four 22Ω resistors in parallel. The 3.3*Ω resistor should be made with three 10Ω resistors in parallel. At each step, connect the resistor just long enough for you to take the voltage measurement. It is normal that when connecting the lower resistance resistors (22Ω or lower) for more than a few seconds, the resistors might get slightly warm. Load 470Ω 100 Ω 47 Ω 22Ω 11 Ω 5.5 Ω 3.3 Ω Voltage across the battery 1.48v 1.46v 1.45v 1.44v 1.4v 1.34v 1.32v Part 4: Using Ohm’s law and the measured voltages obtained above, calculate the load current and power dissipation for each resistor used and tabulate the data in the table. When you prepare your report, sketch a voltage (vertical) vs. current (horizontal) graph. Be sure to label the axes (including units used) of the graph. Load 470Ω 100 Ω 47 Ω 22Ω 11 Ω 5.5 Ω 3.3 Ω Load current ࠵? = (࠵?/࠵?) 3.1mA 14.6mA 30.8mA 65.45mA 127.27mA 243.63mA 372.7mA Power 4.66mW 21.3mW 44.7mW 94.3mW 178.2mW 326.5mW 458.5mW

11 Lab 1 Part 6: Explain why it is necessary to make those parallel connections in step (3) above instead of using a single resistor. (Hint: what is the power dissipation when a 5.5Ω resistor is connected to a 1.5v source and what is the power rating of the resistors? Also, when two identical value resistors are connected in parallel, while the combined resistance is halved, the power rating of the combined resistor doubles.) More resistors we can use, it creates more surface area to dissipate heat effectively. That’s why we use multiple resistors instead of single resistors. Part 7: An ideal voltage source should keep the voltage level constant regardless of the load current. From the graph (assuming 5% voltage variation is acceptably "ideal"), what is the range of the load current in which the battery can be considered an ideal voltage source? y = -0.0004x + 1.4664 1.28 1.3 1.32 1.34 1.36 1.38 1.4 1.42 1.44 1.46 1.48 1.5 0 50 100 150 200 250 300 350 400 Volatge(v) Load current(A) Voltage vs Load current