To: Engineering 120-008 instructor From: Robert Cody Stiltner Date: September 22, 2014 Re: Electrical Circuit Project Lab Report
The purpose of the project was to construct a breadboard with the correct amount of resistors to achieve the correct voltage per node. The amount of resistors was limited so the amount of c alculations were limited to what I could make of it . I was given a network with a predetermined voltage per node, therefore I had to calculate the voltage drop to get the required resistance. The project was built in my dorm room where I did the calculations and put the breadboard together. I placed the resistors in the correct positions and placed the nodes where needed. After calculations and the documentation, such as typing up my work on Microsoft Word and drawing my schematic on Microsoft Visio, I proceeded to the testing period. At the testing period t he board will be tested with a voltmeter and a battery to determine if my calculations were correct. My results were a success. My board passed on the first attempt and was within the plus or minus five percent. My calculations were correct based on the test results. The test results being the readings from the voltmeter. I am pleased with the outcome, but I wish I would’ve spent a little more time to perfect the project. Overall the project went smooth and as planned. Sincerely,
Robert Cody Stiltner 1201 Student
Comment [BH1]: Place academic state here and sign Comment [BH2]: Comment [BH3]: Formatted: Tab stops: 5.2", Left
Electrical Circuit Project Lab Report
September 22, 2014 Author: Robert Cody Stiltner Engineering 1201-008
I have neither given nor received any unauthorized help on this assignment, nor witnessed any violation of the UNC Charlotte Code of Academic Integrity.
Introduction
The design of electrical circuit project is made up of a bread board, resistors, and a testing device. The resistors must be placed in a specific combination to receive the correct voltage drop over each of the five nodes. The resistors must be placed in either series or parallel. Each resistor has a set amount of resistance based off of the color bands that wrap around the resistor. According to the colors on the bands given to me I have the following resistors: 220Ω, 330Ω, 2,200Ω, 3,300Ω, and 10,000Ω. I have five of each of the resistors. All resistors are within±5% of the actual value. The voltage will be tested at each node to determine if the correct resistors were used to determine the set amount of voltage given. The voltage will decrease until the fifth node equals zero volts. Constraints of the project would be the limited amount of resistors, which would limit the number of resistor combinations and the number of alternative designs. The theoretical outcomes should be close to the calculated outcomes assuming no other unknown variables in the project. Background Information For this project I used multiple resources such as books and websites. Ohm’s Law was my most used equation in the entire project. “Ohm’s Law governs the relationship between vo ltage, current and resistance and states that voltage is proportional to current.” I also had to research the colors of the
resistors and find out what the resistance was per resistor. The basic resistance formulas were also needed for this project. Those formulas are resistors in a series and resistors in a parallel. The equations used in this project were as follows.
∑
Comment [BH4]: Number each formula and site it in text
∑ Resistors have a certain power and that power is determined by the color. Therefore we have a color chart to determine the correct amount of power that each resistor has. Below is a chart that shows the color interpretations of a four, five, and six color band resistor.
Comment [BH5]: Resistors don’t have power they have resistance
Figure 1.1
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Methods and Procedures
The equipment involved in the electrical circuit project is a breadboard about the size of t he palm of my hand, twenty-five total resistors. Five resistors of each 220Ω, 330Ω, 2,200Ω, 3,300Ω, and 10,000Ω. Also five copper wires to be used as nodes. I received a half sheet of paper with set amount of voltage drops for each node and a network number of 12. The network number is unique to my breadboard and project individually, individually, so that no one received the same project. I calculated th e amount of voltage drop and from that used Ohm’s Law to determine the amount of resistance needed to acquire the set amount of voltage at the end of the node. I used a scratch piece of paper and a pencil to do this step, so that when I miscalculated I could just erase and start again. I did this for each set node. After all the calculations were complete I continued to write my calculations on Microsoft Word using the equation tool. The equation tool is located under the insert tab at the top of the screen. After I finished my calculations on Microsoft Word I proceeded to do my schematic drawing of my circuit. The schematic drawing must be completed on Microsoft Visio. I did not have Microsoft Visio, so I downloaded it from the DreamSpark program given to UNCC engineering students. After Visio downloaded I played around with it to become familiar with the program. After I had learned enough of the program to do what I needed to do I started drawing my schematic with the electrical template given in the program. The schematic drawing took the most time and a close second was typing the equations in Microsoft Word. I completed all the documentation and proceeded to start on the building of my board. I then began to place t he resistors on the board in the order I thought they would go in according to my calculations. My assumptions were that my project would pass the first test considering that nothing had gone wrong that I could tell. I was limited t o the amount of resistors and what order I could place them in where it be in series or parallel. Sample Calculations
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The first calculation that has to be done is the calculation for the voltage drop.
After calculating the voltage drop you can use Ohm’s Law to determine the amount of resistance
needed.
The total resistance needed is R, and to get the resistance I did the following calculation
Since the 5,000Ω is not exactly what I need I had to calculate the plus or minus five percent i nto my
calculations. The plus or minus five percent comes from the last color band on t he resistor.
Comment [BH8]: Include units( ohms)
Observations and Results
Table1.1 Voltage Divider Node
Required Node to Ground Resistance
Calculated Node Resistance
Tested Node Resistance
Node 1
4777.77Ω
5000Ω
4910Ω
Node 2
6888.96Ω
6886.96Ω
6640Ω
Node 3
7405.56Ω
7370Ω
7370Ω
Node 4
367.89Ω
385Ω
390Ω
Node 5
558.11Ω
550Ω
540Ω
Comment [BH9]: Label the axis and what is series 1?
Percent Difference 4 3.5 3 2.5 2 1.5 1 0.5 0 No d e 1
Node 2
Node 3
Node 4
Node 5
Series 1
Graph 1.1 Discussion
The results of my electrical circuit was a success on the first attempt. As my calculations and the tested values above show that my work was within the five percent difference I did not have to attempt the testing twice. As I stated above that some restrictions would be the availability of resistors. Since I had a limited amount of resistors my project was not perfect. Since some of my percent difference calculations approach close to the five percent I have reason to believe it was because of the constraints I had. My results show that I did my work correctly and proved that my calculations were correct and within the five percent. Conclusion and Recommendations
Overall the project was a success. My breadboard passed on its first try and I did not have to repeat it. Using almost all of my materials given I received what I was expecting to get. A passing project. My percent difference was a little high for each node and I recommend that other students in the future spend a little more time trying to find the lowest possible percent difference. With my high percent difference I was on the borderline of having to redo my project. If more time is spent trying to f ind the best possible way of placing the resistors on the board then the students will not stress as much about their calculations and project as a whole. Engineering assumptions and constraints are useful because future engineers can come up with new innovative ways to do something with what they have to work with. Also being able to learn from what the earlier engineers came up with based off of their laboratory reports. Summary
The purpose of the electrical circuit project is to place resistors on a breadboard, in a specific order, to achieve the correct amount of resistance and voltage drop in a g iven network. I placed the resistors in
Comment [BH10]: Title the chart
series or parallel along the breadboard. There are five nodes and each node has a specific amount of voltage drop and after the fifth node the voltage must be zero. I must calculate the voltage drop and then proceed to calculate the amount of resistance required to reach the correct amount of voltage. The breadboard will then be tested with a voltmeter and battery to determine if the project was done correctly. The calculations were written on Microsoft Word using the equation software. I also produced a schematic of my circuit on Microsoft Visio. I did not know how to operate Microsoft Visio, so I spent a little extra time making myself familiar with the program. The project itself is a challenging task. This project expanded my knowledge in the electrical design and gave me a glimpse the electrical engineering field. I took multiple hours of my day, spread out over two to three days, and researched exactly how one might build a breadboard. I calculated the amount of resistance I had in each resistor based on the color of the bands that wrap around the resistor. I t hen proceeded to calculate the amount of resistance I needed for each node based off of Ohm’s Law. I did this process for each node. After I had done all of my calculations I proceeded to put t he resistors on the breadboard in either series or parallel. The results of my breadboard were a success, although we had to test the breadboard off of resistance rather than voltage which was the original plan. In this specific project I learned that electrical engineering is not for me. I also l earned that more research is required to do this type of project rather than the basic research. I recommend that future students spend a little more time on the calculations and research rather than trying to put the board together. I also recommend that students become familiar with Ohm’s Law and the basic series and parallel formulas.
References "Basic Electrical Circuits Explained." Electrical Information Resource. January 1, 2013. “Electrical Theory PrePre -Class Reading.” Electrical Theory. August 15, 2014. Dorf, Richard C., and James A. Sv oboda. Introduction to Electric Circuits. 7th ed. Hoboken, NJ: J. Wiley & Sons, 2006. Smith, K. C. A., and R. E. Alley. Electrical Circuits: An Introduction. Cambridge [England: Cambridge University Press, 1992. "Circuits." In The Electrical Engineering Handbook, edited by Richard C. Dorf. 2nd ed. B oca Raton: CRC Press, 1993.
Appendix
Comment [BH11]: Add schematic and all work to the appendix