Write engineering report

Report submitted on: September 6, 2018

Table of Contents

Section Title Page

Table of Contents ii

List of Tables ii

1.0 INTRODUCTION 1

1.1 Background 1

1.2 Purpose 1

2.0 METHODOLOGY 2

2.1 Equipment 2

2.2 Procedure 2

3.0 RESULTS AND DISCUSSION 3

4.0 CONCLUSION 7

LIST OF REFERENCES 7

ii

List of Figures

Number Title Page

1. Cycles 4

2. Cycles 4

3. X-Y scale 6

4. DMM Error Vs. Frequency 6

LIST OF TABLES

Number Title Page

1 AC Coupling Values 6

2 DC Coupling Values 6

3 DMM Percentage Error 6

iii

Introduction

Background

In D.C. circuits the power delivered to a circuit element is given by the product of the voltage across the element and the current through the element. This is also true of the instantaneous power to a resistor in an A.C. circuit. For many applications the instantaneous power is of only minimal interest and the average power delivered over time is of primary interest. This is particularly true in power systems. In order to have an easy way of measuring power the effective or rms method of measuring voltage and current was developed. The effective value is defined as the value of the equivalent D.C. quantity that would deliver the same average power to the same resistor. Since power is given by p(t) = v(t)i(t) = v(t)2/R = i(t)2R, it is necessary to integrate to find the average value of the power.

For a periodic function the average is found by integrating over one period and dividing by the period. For D.C. power the average and the instantaneous values are the same since it is a constant. Therefore, by setting the equivalent D.C. power for a periodic function

If v(t) = Vmsin(t) then

Methodology

Equipment

Resistors: 10 KΩ, 15 KΩ.

Capacitor: 0.01 µF.

Oscilloscope.

Digital Multimeter.

Elvis II Breadboard.

Procedure

The student was asked to construct an electric circuit. The students then were asked to set the signal generator at 2 kHz and 1.8 Vrms, also set the DC power supply to 9 Vdc. The student was required to connect channel one of the oscilloscope and channel two to specific nodes in the circuit. The students were asked to sit the oscilloscope for AC coupling then record peak to peak and rms voltages of each wave form, and repeat for DC coupling. The student was asked to determine the phase shift on an X-Y scale and Y-T scale.

For the second procedure, the student was required to connect the digital multimeter to the signal generator output. The students were asked to set the voltage level at 1 Vrms and multiple frequencies of (1, 2, 5, 10, 20, 50, 100, 500) kHz, and note the readings on the oscilloscope and the multimeter. The student was required to graph the error VS. frequency, and then compare the error tolerance on the DMM spec sheet with the results.

-Results & discussions

Procedures each one have different measurement, for the first one the student started with measuring the values of the resistor to make sure the values are identical for the give values and then the student started constricting the circuit by connecting the nodes 1 and 2 and 3, then we powered the signal generator to set it up in certain frequency and it connected to node 1 and set to 2 kHz with 1.8VRMS supping the power generator to 9V and also was connected to node 3. by connecting CH1 of the oscilloscope to the nodes then by setting both oscilloscope to AC coupling and DC coupling to find the measurement.

The rms voltage for the above wave form can be derived as follows:

By connecting CH1 of the oscilloscope to node 1 and CH2 to node 2 to fine the time scale to display one or two complete cycles.

Fig.1

At least one complete cycle of a waveform on the screen in order for the oscilloscope or Wave star to calculate some of the measurements:

Fig.2

Table 1: AC Coupling Values

Table 2: DC Coupling Values

Table 3: DMM Percentage Error

Switch back to ac coupling on both channels and set the Scope to x-y mode and determine the phase shift between the ac waveforms at node 1 and 2, using the elliptical pattern.

The phase shift on an X-Y scale and Y-T scale:

By comparing the data given the error tolerance was found:

Figure 3: DMM Error Vs. Frequency

-Conclusion

In conclusion, the student was measured the AC and DC voltage by using the oscilloscope in sufficient frequency rather than a DMM. The student observed the error tolerance by comparing the data which makes the student well know leadable using the instrument.

-References

-Arkansas State University Engineering Course Standards bulletin (http://www.astate.edu/college/engineering/files/EngineeringCourseStandards2014.pdf)

-Appendix

Appendix A- Handout

DMM Error Vs. Frequency

1.0 2.0 5.0 10.0 20.0 50.0 100.0 500.0 2.0 2.0 31.36 59.43 81.19 99.44 99.9 99.9