EET-117 LAB 3 F20

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Centennial College ELECTRICAL ENGINEERING TECHNICIAN & TECHNOLOGY Course: EET-117 Name Baljot Tatla Student Number 301152364 Date Lab #3 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): _____________________ 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 BAN D # 4 Resistor value (Ω) Resistance range (calculated) DMM Measurement ( Ω ) % Dif. Is a toleranc e within the range? (Y/N) Mark 1ST DIGIT 2 ND DIGIT x10n Multiplier ±% Toleran ce Min (Ω) Max ( Ω ) 1 2 3 4 5 6 7 8 9 10 11 1 Color red red 10(2) 5% 2200 2310 2090 2168 -1.45 y /5 Code # 2 2 2 2 Color red black 10(2) 5% 2000 1900 2100 1977 -1.5 y /5 Code # 2 0 2 3 Color brown Black orange 5% 10000 9500 10500 9842 -1.58 y /5 Code # 1 0 10(3) 4 Color Blue Gray red 5% 6800 6460 7140 6690 -1.6 y /5 Code # 6 8 10(2) 5 Color Red violet Red 5% 2700 2565 2835 2650 -0.01 n /5 Code # 2 7 2 6 Color Brown Green red 5% 1500 1425 1575 1466 -2.6 Y /5 Code # Are all the measured values for the resistors within the manufacturer's tolerance specifications? Indicate those that are out of 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 06.68 6690 2.16 2168 Do you observe any difference between the two measurements? Expain below 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 = 10.48 /1 Step Shaft Position Resistance Measured Between: Sum of Resistance Readings Terminals 1-2 Terminals 2-3 10 O degrees (fully CCW) 0.0006 4.87 9.77k /3 11 90 degrees CW 4.78 4.86 9.98k /3 12 180 degrees CW 4.87 0.0006 9.56k /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? By test another resistor of the same color code. 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 . 8.538 x 10^3 Ω 8538 Marks: / 4 3. D e termine the resistor color code for the following resistors. 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 Gold / 2 9100 Ω White Brown Red gold /2 6.8 kΩ Blue Grey red gold /2 120 Ω Brown Red Brown gold / 2 1.00 Ω Brown Black gold green /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 220 (5%) / 2 v iolet green Brown silver 750 (10%) /2 gr e en brown Brown gold 510 (5%) /2 whi t e brown Gold gold 9.1 (5%) /2 grey red Yellow s ilver 820000(10%) /2 Marks: / 10 5. A resistor is col o r - coded red - violet-orange-gold. N Question Answer Mark Q1 What is resistance value of the resistor? 27000 /2 Q2 What is the largest value the resistor can be and still be in tolerance? 28350 / 2 Q3 What is the smallest value the resistor can be and still be in tolerance? 25650 /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. Because it has totally different tolerances and always show bit higher as well. Marks: / 8

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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 % 536.6Ω 541.36Ω /4 2 orange orange black yellow red 3.30 MΩ ± 2 % 3.234MΩ 3.366MΩ /4 3 write orange blue red brown 97.6 kΩ ± 1 % 96.525KΩ 98.576KΩ /4 4 violet green black gold red 75Ω± 2 % 73.5Ω 76.5Ω /4 5 brown green black black brown 150Ω± 1 % 148.5Ω 151.5Ω /4 Marks: /20 Conclusion. The conclusion summarizes important points of the laboratory work. It may refer to figures or tables previously discussed in the body of the report to add emphasis to significant points. Conclusion, safety is number one priority in a lab and we always must take precaution order not to do any damage the devices in a lab. I determined all value of resistor which was all correct by using DMM to measure the resistor. Marks: / 30 Rubric-Grading Criteria Max. Marks Punctuality 10 Individual Participation 20 Lab Safety 20 Procedure 50 Review Questions 60 Conclusion 30 Neatness, Spelling, Grammar, and Sentence Structure 10 Total: /200

EET-117 LAB 3 F20

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