Herrera_ME455_Lab1

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Metropolitan Community College, Kansas City *

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455

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Mechanical Engineering

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Feb 20, 2024

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pdf

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FALL2021. ME 455. Mechanical Engineering Measurements and Experiments Experiment #1. Basic Instrumentation Name: Brandan Herrera Lab Section: Wednesday 10:00-11:50 Group Members: Hal Vieyra, Seth Harper Section 1. Experiment summary (15 Points) (~250 words) In this laboratory, familiarity and proficiency with common instruments are essential for future laboratories in the class. Four primary instruments that will be used through the semester include the function generator, oscilloscope, DC power supply, and digital multimeter, each serving distinct purposes in experimental setups and evaluations. The function generator generates various waveforms like sine, square, or triangular waves at different frequencies and amplitudes. By using the function generator, it can be connected to the oscilloscope which visually displays electrical signals, helping in waveform observation, measurement, and troubleshooting. As well as the function generator, a DC power supply can be used as well with the oscilloscope by producing a constant voltage and can be viewed on the oscilloscope. The digital multimeter serves as a versatile tool for measuring voltage, current, resistance, and continuity in circuits. By selecting appropriate measurement ranges, one can interpret readings accurately to assess circuit parameters. To master these instruments, hands-on practice and comprehension of their functionalities are ideal. Groups were tasked to set desired waveforms on the function generator, interpret signal behavior on the oscilloscope, regulate voltage and current on the DC power supply, and measure various parameters using the digital multimeter. By gaining proficiency with these instruments, execute experiments accurately, troubleshoot circuit issues that should arise in future experiments. As well as being able to see how different lengths of cord from the DC power supply can affect the sample rate, signal frequency and signal amplitude to demonstrate how choosing different wire lengths may effect the results you are looking for versus the result that you received from the experiment. Section 2. Recorded data (40 Points) Table 1: Measurement of a signal output from FG using OS and DMM Signal Waveform Amplitude set V pk-pk [V] Frequency set [Hz] Amplitude RMS [V] Frequency measured [Hz] OS DMM OS DMM Sine ~2 100 2.1 0.681 100 100.2 Sine ~0.8 10 0.8 7.56 10 10.7 Sine ~4 9k 4 0.9 8.99k 8.99k Sine ~0.4 9k 0.4 0.08 8.99k 0.00 Sine ~ 10 5M 10.2 0.023 5.00M 0.00 Sine ~ 0.5 5M 0.503 0.00 5.04M 0.00 Square ~ 0.8 10 0.79 0.384 10.36 10.36 Square ~ 2 9k 2.05 0.545 9.03k 9.003k Square ~ 10 5M 10.1 0.021 5.03M 0.00 Triangle ~ 10 5M 10.1 0.000 5.04M 0.00 Triangle ~ 2 9k 2.01 0.366 9.08k 9.002k Triangle ~0.8 10 0.81 0.219 10.015 10.01 Table 2: Comparison of measuring a signal RMS voltage using OS and DMM Method Voltage [v] % Error Expected RMS Voltage 1.41 0 OS Measured 2.01 30

2 | P a g e RMS Voltage DMM reading 0.688 51.2 Table 3: Resistor Measurements Resistor Value from DMM (with units) Color Band Resistor 1: 148 OHMS B,G,B,S Resistor 2: 272.4 OHMS R,P,B,S Resistor 3: 152M OHMS B,G,Y,S Table 4: Measuring a Signal in Air Antenna length OS Sampling rate Signal frequency Signal amplitude Sinusoidal wave? 8 ft 500M samples/s 178 kHz 1.3 V Yes 3 ft 10 in 2G samples/s 92.8 MHz 6.9 mV Yes Section 3. Plots and analysis (0 Points)  N/A Section 4. Questions (30 Points) Question 1 : Check your RMS and Frequency measurements using OS and DMM in Table 1. Are they always very close in value? Explain your result. Answer 1: Some of the values are pretty spot on because they are within the range of both machines. On the parts that not close to each other can either be instrument set up, user error or there were not enough significant figures to produce a Mega Hertz when it could produce a kilo Hertz.If the DMM was able to read megahertz then the values would match up pretty close to the values from the oscilliscope. Question 2 : Set OS input terminal to DC coupling, what happens to the signal shown on OS when the DC OFFSET button on FG is pressed in and adjusted off-center? Answer 2:

3 | P a g e In DC coupling, the DC component is removed from the main component but visually, nothing much happens only where the off set starts. When both are in the main component, the offset is at a certain value but after DC coupling the offset starts at 0. Question 3 : Set OS input terminal to AC coupling, what happens to the same signal shown on OS when the DC OFFSET button on FG is pressed in and adjusted off-center?? Answer 3: In DC coupling, the AC component is removed from the main component to which in a visual sense, nothing happens because it is only the DC that dictates the initial starting point of the wave or in other words the offset that is going on between the oscilloscope and the function generator. Question 4: What happens to the square, triangle, and sine waves when the DUTY CYCLE is rotated clockwise and counterclockwise? (Hint: make a chart that describes changes, if any, in the frequency, RMS voltage, rise time, fall time and overall appearance for the signals.) Answer 4: In AC coupling, the DC component is removed from the main component to which visually, the amplitude of the wave does not change but what does change is the start of the offset. When both are in the main component, offset is at a certain value but when DC value is removed, the start of the offset is at 0V. Question 5: Describe in detail how to measure the current in the following circuit using the DMM. Draw this connection on the schematic. Place an X through any connection(s) that need to be disconnected, if necessary. Electrical Device Power Supply + - D C

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4 | P a g e Section 5. Conclusions (15 Points) (~100 words)  Did the group complete the goal of the lab? Stating yes or no is insufficient for labs with more data driven goals. In this exercise’s case the goal is get “hands on” experience with the data analysis of wave functions and gain an understanding of the types of errors that can occur when sampling incorrectly.  What would you change about this lab? What data (if any) could you not obtain? Be specific as to the reason you would change the lab. If you feel that you didn’t meet the criteria for success on this lab how might you change that? The digital multimeter should be placed at the X location. This is because you get the most accurate representation of the current that flows through the circuit. If the DMM was placed after the electrical device, it could have some sort of resistor that could affect the current going through the circuit. The circuit does not need to be broken at any place unless it is to input the DMM to which the positive wire (red wire) would be the first wire the circuit touches and it would end with the black wire of the digital multimeter completing the circuit. Yes, the group completed the goal of the lab. It is possible to see that in the provided tables above showing how similar each voltage and hertz measurement was between the oscilloscope, digital multi meter, and the function generator. There was a little bit deviation that occurred mostly around the megahertz area because the digital multimeter could not read a value that high with the largest it was able to show was in the kilohertz area. What could have also gone wrong was the base knowledge of figuring out how to read the multimeter to be able to read the megahertz. I would change the lab by students using different voltages as an input and send it through different size resistors, capacitors and inductors so that it can produce a wave function on the oscilloscope. That would be a great way for students to see how resistors and other resistances can affect the results of voltage running through a circuit and still understand how to use these certain machines.