Jeewan open lab

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Centennial College *

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Electrical Engineering

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Dec 6, 2023

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Centennial College ELECTRICAL ENGINEERING TECHNICIAN & TECHNOLOGY Course: EET-117 Name Jeewan Parajuli Student Number 301320619 Date 09/28/2023 Lab #4 MEASUREMENT OF RESISTANCE Based on Experiments in Basic Circuits by David Buchla Objectives: 1 Determine the listed value of a resistor using the resistor color code. 2. Use the DMM (or VOM) to measure the value of a resistor. 3. Determine the percent difference between the measured and listed values of a resistor. 4. Measure the resistance of a potentiometer and explain its operation. Required Instruments and Components: DMM (Digital Multi-meter) VOM Power supply Breadboard Alligator test leads (from the EET-117 labkit) Resistors: 6 assorted value resistors (from the EET-117 labkit) Potentiometer of any value (from the EET-117 labkit – example: when it is labeled “103” it is – 10x10 3 Ohm or 10 kOhm resistor)

Procedure 1. Orient the 6 resistors so that the color bands may be properly read from left-to-right on the breadboard as is shown in Figure 1. Make sure to leave a 5-hole spacing between the resistors to facilitate individual measurements. Fig. 1 2. Determine the color codes for the resistors and record them in the Table 1. 3. Before taking any resistance measurements with the DMM, always make sure to check the meter's ZERO ERROR. Our DMM (Keithley 2110) has auto-zero function automatically turned ON (p.81 of the manual). Over time and prolonged use, meters tend to go out of proper calibration and this will result in ZERO ERROR. In addition to above, the test leads (their resistance) may impact the correctness of the readings. Use NULL function to correct test lead’s resistance. When the null feature is enabled, the displayed reading is the difference between the measured input signal and the stored null (also called relative) value: Displayed reading = Measured input reading - Null value You can acquire the null (relative) value by measurement or by specifying the value. The null value is stored in volatile memory, which will be cleared when power to the instrument is cycled. Cancel out test-lead resistance that can result in inaccurate low-level resistance Measurements. The subsequent resistance measurement reading will exclude the test lead resistance. a. Turn the DMM ON b. Press 2 to select 2-wire ohm measurement. Ω c. Connect test leads to the instrument as shown below and connect them together (without a resistor). Fig. 2 d. Record the Resistance value shown on the display (test-lead resistance): ______0.690_______________ e. Use NULL function to correct test lead’s resistance.

Fig. 3 4. With the Digital Multimeter (DMM) measure the actual ohmic value for each resistor and enter the results into Table #1. IMPORTANT: Make sure to wait for the meter's reading to stabilize before recording it into the table. 5. Use the % tolerance value to calculate the Minimum and Maximum possible resistance values for each resistor (Resistance Range) and determine (Yes or No) if the measured values falls within the tolerance range specified by the manufacturer. 6. Compute the percent difference between the measured and color-coded values using the equation: Table 1. Experimental data readings (columns 2-5 and 9 to be completed in the lab). 4 1 1 1 1 1 RESISTOR BEING TESTED BAND # 1 BAND # 2 BAND # 3 BAND # 4 Resisto r value (Ω) Resistance range (calculated) DMM Measurement ( Ω ) % Dif. Is a tolera nce withi n the range ? (Y/N) Mark 1ST DIGIT 2ND DIGIT x10n Multiplier ±% Tolerance Min (Ω) Max ( Ω ) 1 2 3 4 5 6 7 8 9 10 11 1 Colour Green blue red gold 5.6k Ω 5.32 k Ω 5.88k Ω 5.508 k Ω -1.64% Y /5 Code # 5 6 2 5 2 Colour Orang e orang e red gold 3.3k Ω 3.135k Ω 3.465k Ω 3.2509k Ω -1.49% Y /5 Code # 3 3 2 5 3 Colour violet green red gold 7.5k Ω 7.125k Ω 7.875k Ω 7.4832k Ω -0.22% Y /5 Code # 7 5 2 5 4 Colour black violet orange gold 7k Ω 6.65k Ω 7.35k Ω 6.8538k Ω -2.09% Y /5 Code # 0 7 3 5 5 Colour blue grey red gold 6.8k Ω 6.46k Ω 7.14k Ω 6.7317k Ω -1.01% Y /5 Code # 6 8 2 5 6 Colour yellow violet red gold 4.7k Ω 4.465k Ω 4.935k Ω 4.6306k Ω -1.48% Y /5 Code # 4 7 2 5 Are all the measured values for the resistors within the manufacturer's tolerance specifications? Indicate those that are out of tolerance. The measurements are all within the manufacturer’s tolerance. Marks: / 30

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7. Remove all resistors from the breadboard but set aside two resistors with the largest and the smallest value for the next measurements. 8. Re-measure the values of the two resistors, but don't place them in the breadboard for measuring, instead hold the resistor leads and the meter probes between your fingers as shown in Figure 4. Record the readings in Table 2. Fig. 4 ( NOTE : This is an INCORRECT way of measuring resistance) Table 2 (all columns to be completed in the lab). Measured value as per Fig. 4 Measured value as per Table 1 6.5503 k Ω 6.7317k Ω 5.3602 k Ω 5.508 k Ω Do you observe any difference between the two measurements? Expain below When I re-measured the values of the two resistors by holding the resistor leads and the meter probes between my fingers, as shown in Figure 4 (although it's essential to note that this is an improper way of measuring resistance), I noticed a variance in the measured values compared to the measurements taken when the resistors were placed in the breadboard, as recorded in Table 1. This variance can be attributed to the fact that the resistance of my fingers is not constant and can fluctuate due to factors such as moisture, temperature, and pressure. When I held the resistor leads and meter probes, my fingers essentially introduced an additional resistance in series with the resistors being measured. This extra resistance affected the accuracy of the measurements, resulting in the deviations. Marks: / 10

9. Use any potentiometer from your labkit. Number the terminals 1, 2, and 3, as illustrated in Fig. 5. Get familiar with a spec sheet in the Appendix A of the theory part of the lab. Vary the potentiometer's shaft while you monitor the resistance between terminals 1 and 3. Notice that the resistance between the outside terminals does not change as the shaft is varied. Record the resistance between terminals 1 and 3 of the potentiometer (the outside terminals) in Table 3. Fig. 5 10. Turn the potentiometer completely counterclockwise (CCW – this potentiometers have adjustment of 280 degrees nominal). Measure the resistance between terminals 1 and 2. Then measure the resistance between terminals 2 and 3. Record the measured resistances in Table 3. Compute the sum of the two readings and record it in Table 3. 11. Turn the shaft 90 degrees clockwise (CW) and repeat the measurements in step 10. 12. Turn the shaft another 90 degrees (180 degrees total) in the same direction (CW) from the starting point and repeat the measurements in step 10. Table 3 Marks Step 9: Total resistance between terminals 1 and 3 = 0.97098 k Ω /1 Step Shaft Position Resistance Measured Between: Sum of Resistance Readings Terminals 1-2 Terminals 2-3 10 O degrees (fully CCW) 0.14833k Ω 0.82265k Ω 0.97098k Ω /3 11 90 degrees CW 0.12606k Ω 0.83660k Ω 0.96266k Ω /3 12 180 degrees CW 0.446k Ω 0.48784 k Ω 0.93384k Ω /3 Marks: / 10 REVIEW QUESTIONS

1. You suspect that the percent difference between color-coded and measured values could be due to error in the meter. How could you find out if you are correct? Well, the colour-coded values provide a certain value range, if you’re measured value falls between those range values, you’re most likely correct. If you wanted to go further, you could do things such as recalibrating the machine or using multiple DMM’s and if you’re measurement is consistent then it’s another indication that you’re correct. Marks: / 2 2. Predict t h e resistance between terminals 1 - 2 and 2 - 3 for the potentiometer if the shaft is rotated fully CW . If the resistor rotated fully CW between terminals 1-2 and 2-3 then should be 970 Ω . This is because "clockwise," implies that the resistor's wiper has been rotated fully between terminals 1-2 and 2-3, and so it would at it’s maximum. Marks: / 4 3. Determine the resistor color code for the following re sistors. The tolerance is 10%. Value 1 st band colour 2 nd band colour 3 rd band colour 4 th band colour Mark 7 MΩ Violet Black Green silver / 2 9100 Ω White Brown Red silver /2 6.8 kΩ Blue Gray Red silver /2 120 Ω Brown Red Brown silver / 2 1.00 Ω black Brown Black silver /2 Marks: / 10 4. Determine the expected value for resistors with the following color codes. 1 st band colour 2 nd band colour 3 rd band colour 4 th band colour Value Mark red red black gold 22Ω ± 5% / 2 v iolet green brown silver 750Ω ± 10% /2 gr e en brown brown gold 510Ω ± 5% /2 whi t e brown gold gold 9.1Ω ± 5% /2 grey red yellow s ilver 820kΩ ± 10% /2 Marks: / 10 5. A resistor is color-coded red-violet-orange-gold. N Question Answer Mark Q1 What is resistance value of the resistor? 27k Ω /2 Q2 What is the largest value the resistor can be and still be in tolerance? 28.35k Ω / 2 Q3 What is the smallest value the resistor can be and still be in tolerance? 25.65k Ω /2 Marks: / 6 6. Explain why ex p erimen t al calc u lations s h ould use me a sured values o f resis t ors rather than color co de d values.

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Experimental calculations should be made using measured values of resistors rather than color-coded values because the actual resistance of a resistor can deviate from its color-coded value due to manufacturing % tolerances and other factors. Using measured values ensures that the experimental results are as accurate as possible. Additionally, using measured values can help identify any faulty or defective components in the circuit. Marks: / 8 7. This experiment described how to read 5% and 10% tolerance resistors. The same idea is used for most 1% and 2% resistors except that 1% and 2% will have one more color band than 5% and 10% resistors. The first three bands represent the first, second, and third significant figures. The fourth band represents the multiplier band. The decimal point is assumed to be after the third significant figure and then moved by the amount shown in the multiplier band. The fifth band represents the tolerance band. A 1% resistor has a brown tolerance band and a 2% resistor has a red tolerance band. There is a space between the fourth and fifth bands to avoid mistaking the tolerance band for the first significant figure and mistakenly reading the resistor backwards. For each of the resistors shown in Table 4, find the remaining information and complete the table. The first line is completed as an example. Table 4 Resistor Colour of Band Colour-code value Minimum value Maximum value Mark 1 st 2 nd 3 rd 4 th 5 th 0 brown red violet brown gold 1.27 kΩ ± 5 % 1.24 kΩ 1.30 kΩ 1 green orange blue black brown 536 Ω ± 1 % 530.64 Ω 541.36 Ω /4 2 orange orange black yellow red 3.30 MΩ ± 2 % 3.234M Ω 3.366M Ω /4 3 white violet blue red brown 97.6 kΩ ± 1 % 96.624k Ω 98.576k Ω /4 4 violet green black gold red 75 Ω ± 2 % 73.5 Ω 76.5 Ω /4 5 brown green black black brown 150 Ω ± 1 % 148.5 Ω 151.5 Ω /4 Marks: /20 Conclusions. The conclusion summarizes the important points of the laboratory work. You must analyze the examples to add emphasis to significant points. You must also include features and/or things you have done /benefits of a particular procedure, instrument, component, or circuit directly

related to the experiment . In conclusion, I found this to be highly informative and valuable in achieving its objectives. Which consisted of firstly using the DMM machine and connecting probes to resistors. Secondly, learned how to interpret resistor color codes to determine their listed values accurately. Thirdly, Calculating the percent difference between measured and listed resistor values provided me with a crucial understanding of measurement precision. Lastly, we took our measurements, took what we learned, and applied it to more theoretical things like the tables we had to fill in. This experience has provided the skills and knowledge necessary for future pursuits in electrical engineering. Marks: / 20 Rubric-Grading Criteria Max. Marks Punctuality 10 Lab Safety 20 Procedure 50 Review Questions 60 Conclusion 20 Neatness, Spelling, Grammar, and Sentence Structure 10 Total: /170

Jeewan open lab

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