Lab Report 1

docx

School

University of Texas, Rio Grande Valley *

*We aren’t endorsed by this school

Course

MISC

Subject

Electrical Engineering

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by JusticeGalaxyWaterBuffalo22

ELEE 3101.02 Lab 1: Accurate Measurement Techniques September 22, 2021 Brandon Mireles-Soto & Salvador Gonzalez

ABSTRACT: In this lab we went ahead and tested different equipment, to see how accurate they are when measuring in different circumstances. We went ahead and tested rms values by using a signal generated by the function generator with our projects group letter D and also change the frequencies to different values. We then use the oscilloscope to verify the waveform and the also the built-in function measurement for rms to find its value. we also calculate the rms value by using the bench multimeter and they come withing 3% of the actual value. We then perform another similar test, use the function generator to create a sine wave with a given value for our frequency, and measure both peak-to-peak and rms values with different instances for the scale and probe, and then find the period for the wave. Another test we do for this lab it to find the effects of connecting a measurement instrument to a circuit, in this case we measure the rms voltage using an oscilloscope with probes X1 and X10, and also by using the bench multimeter in a circuit. The circuit consists of resistors with points A and B as the points of measurements. For our final testing's we analyze the difference in using AC vs DC coupling with a given triangular wave and its values., and by finding the values of our function generator given specific values obtained with Project D. We then calculate the rms value of the waveform by integration and compare our results with the bench multimeter and oscilloscope values to make sure there within a 3% margin. The most important results observed is that the bench top multimeter gives more accurate reading when measuring rms at certain frequencies, and how just by adjusting the vertical and horizontal scale can give us a better measurement and how in AC vs Dc coupling, AC can sometimes be the better alternative when looking at a wave form. We can also find what values are needed to produce our desired wave form. PARTS: - Oscilloscope - Two Resistors 1.6kΩ - Two Resistors 820kΩ - Function Generator - Bench top Multimeter - DC Power Supply

PROCEDURE: Part I: Comparison of Measurement Instruments - Frequency Limitation Group D: 6 Volts peak to peak (1) The function generator was setup to output a 60 Hz sine wave, with zero offset and peak to peak voltage of 6. Figure 1.1: Waveform 6V pk-pk at 60Hz (2) The calculated RMS value for this waveform is shown below. V rms = 1 2 √ 2 ∗ V p − p = 1 2 √ 2 ∗ ( 6 ) = 2.121 V (3) Using the RMS measure function and the benchtop multimeter our RMS values we yielded are RMS Function: 2.20V

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Multimeter: 2.11V (4) The calculations all agree within 3% (5) The measurement from step (3) was repeated at the following frequencies: 5 Hz, 10 Hz, 20 Hz, 50 Hz, 100 Hz, 200 Hz, ……, 10 MHz. Table is listed below. Part 1 Table for given frequencies (6) In your notebook, discuss the results of your measurements. Over what range is the multimeter highly accurate? Over what range is it useful? The multimeter was more accurate when we implemented 100 Hz to the power generator. We found out that over the range of 10Hz the waveform was useful. Part II: Appropriate Use of Scale Group D: 2.5 kHz (1) Set up your function generator to produce a sine wave with - Frequency at 2.5kHz - Amplitude set to the smallest value allowed by the function generator, but not less than 20 mV pk-pk.

Figure 2.1: Waveform at 20mV pk-pk and 2.5kHz (2) Using Excel, Table 3 is shown below

Part 2 Table 3 (4) Discuss the results of Step (3). In your judgment, what is/are the best vertical scale and probe settings to make this measurement? The best vertical scale to use is 20.0mV per division since it gave us a better image of the waveform, and the best probe setting to make the measurement was X1. (5) Set the vertical scale and probe to the settings you think are best. Period is shown below using 3 different methods. (a) Using the cursor function on the scope to measure the time difference between peaks. ∆t = 404 μs (b) Using the cursor function on the scope to measure the time difference between zero crossings. ∆t = 404 μs (c) Using the automatic period measurement on the scope. ∆t = 404 μs (6) Repeat all three period measurements using each of the following horizontal scales Horizontal Scales Measurements 0.1ms/div 397 μs 0.2ms/div 400 μs 1.0ms/div 396 μs 2.0ms/div 400 μs (7) Compare your results from Step (6) to the theoretical value (T = 1/f). Discuss the results in your notebook. Which scales or scales give best accuracy, in your judgment? Is it more accurate to measure between zero crossings, or peaks? Using the horizontal scale of 2.0ms/div gave us the best accuracy since the waveform was given us a better reading than the other scales. We believe that measuring between peaks gave us a better measured value since it compared precisely with our calculations.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Part III: Effect of Instruments on Circuits Figure 1 – Probe Compensation (2) Construct the circuit shown in Figure 2 below, using component values from Table 4. Set up the function generator to output a 100 Hz sine wave, 8V peak-to- peak. Calculate the rms voltage expected at points A and B with respect to ground. Figure 2 – Circuit for Part III Group D: R1= 1.6K & R2= 820K (3) Accurately measure the rms voltages at points A and B using three methods (a) the oscilloscope probe set to X1 (or using an ordinary BNC-clips lead), (b) the oscilloscope using the X10 probe, and (c) the benchtop multimeter. Include scope shots (four pictures). Use your judgment to pick good scales.

Figure 3.1: Waveform at 8V pk-pk and 100Hz Figure 3.2: Waveform at 8V pk-pk and 100Hz (X1 probe)

Figure 3.3: Waveform at 8V pk-pk and 100Hz (X10 probe) Figure 3.4: Waveform at 8V pk-pk and 100Hz (Multimeter)

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

(4) Before going on to the next step, calculate the theoretical rms voltages at points A and B assuming no measurement device is connected. Compare your results from step (2) to the theoretical value and explain which measurement methods were most accurate, and why. Calculated Point A Measured Point A Calculated Point B Measured Point B 2.86V 2.857V 1.345V 1.40V Using the measuring tool function in the oscilloscope we were able to get the most accurate measurements since it gave precise results. Part IV – Use of AC versus DC coupling. (1) Using the scope, set up your function generator to produce a triangle wave with the amplitude and frequency shown below. Group D: Amplitude 0.4 V pp & Frequency 5kHz (2) Then set up one channel on your power supply to voltage and current shown below. Group D: 8V , 0.1Amps (3) Then connect the function generator, power supply, and scope as shown in Figure 3. Figure 3. Measurement for Part IV

Figure 4.1: Waveform at 0.4V pk-pk and 5kHz (power supply @ 8V and 0.1Amps (5) Use your judgement to find the coupling, vertical, and horizontal scales to most accurately measure each of the following, without changing the hookup in Figure 3. (a) Peak-to-peak voltage V pp =3.76mV (b) Average voltage V avg = 234 mV (c) Period Period= 200µs Part V: Comparison of Measurement Instruments - Nonsinusoidal Waveforms For this section you will need a function generator capable of putting out a pulse waveform as shown in Figure 4 below.

Figure 4 – Waveform for Part V Group D: V1= -2V, V2= 7V, T1= 1ms, T2= 3.5ms (1) Set up the waveform, using the oscilloscope to verify. Figure 5.1: Waveform at 9Vpk-pk and 222Hz

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Figure 5.1: Waveform at 9Vpk-pk and 222Hz (@2ms/division) (2) Calculate the rms value of the waveform by integration. You will need the number for the next step.

(3) Then measure the rms value of the waveform by two methods (a) the rms measure function on your oscilloscope, (b) the benchtop multimeter. Record the results and compare to your calculations. The oscilloscope should match your calculations to within 3%. The multimeter may or may not give accurate results The rms value we calculated was 3.62v and using the function for rms in the oscilloscope gave us 3.84v, and for the multimeter we didn’t get an accurate result.

CONCLUSION: In the first part of the lab, we explored the basics of using an oscilloscope. We got familiar with the function generator and learned how to produce a signal with the given amplitude and frequency. We then used the oscilloscope to verify the waveform and make sure our measurements were accurate. We saw a how changing the frequency can make our waveform unstable. After testing frequencies between 5Hz-10MHz we learned that the best value to give us accurate results is 100Hz since the waveform is not too unstable and lets us record accurate values. The second part of the lab included using the scale function on the oscilloscope. We saw how adjusting the vertical and horizontal scale can give us a more accurate reading of the waveform that was produced in the oscilloscope. Using the cursor function we were able to use different methods to measure the time difference. In our case, measuring between peaks gave us the best overall results. The third part of the lab included the use of resistors to take measurements of a circuit. We calculated the RMS of the points A and B in the circuit and then used the Oscilloscope to confirm the correct RMS. We compared the values and found that both values were within 3% error confirming that we got the correct measurement. The fourth part of the lab included allowed us to implement the power supply to create a waveform on the oscilloscope. We experimented with using AC and DC couplings and found that AC gave us better reading in the scope. This part also provided us with more practice in

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

using the scales since we had to find the correct units per division to give us a accurate reading in the scope. In the last part of the lab, we experimented with the function generator to produce the waveform that was included in Figure 4. We had to change the value for the offset in order to give us the correct Max and Min values. We also had to calculate the RMS by integration and notice that our calculations were close to the RMS in the scope. Overall, this lab helped us grasp better knowledge of the oscilloscope and provided a deeper understanding on how to use all the functions of the scope. It was interesting to find how close the calculations we made by hand came with the measurements in the oscilloscope. We believe that the values we obtained throughout the lab are very accurate with that of the measured values.