Introduction to Laboratory Equipment - DC Circuit Analysis | ECE 103, Study notes of Electrical and Electronics Engineering

Download Introduction to Laboratory Equipment - DC Circuit Analysis | ECE 103 and more Study notes Electrical and Electronics Engineering in PDF only on Docsity! ECE103. Spring 2012 Experiment #3 Student name(s) and lab section: Page 1 from 6 Experiment #3 Introduction to Laboratory Equipment Objective: In this lab you will be introduced to basic laboratory equipment that you will use in the rest of the course. You will also explore the behavior of simple DC circuits. * Methodology: This lab involves measuring voltage and current and performing calculations. You are expected to show your results and work in this packet or also attach additional pages. * General Procedures: Please read before you start working • You must take good care of the equipment and follow basic safety rules in order to maintain the equipment in good working conditions, and to prevent accidents. • Always check connections before applying power to any circuit or device. You do not want to exceed the power limitations of the device or otherwise it will be damaged. • When using the multimeter and you are not sure of the approximate values you will be measuring start by selecting the least sensitive scale setting then slowly work your way down. • Disconnect power supplies (current and voltage sources) from a circuit before measuring resistance as multimeters use internal power sources when measuring resistances. • Switch the power supply off when making adjustments in your circuit connections or when adding new components to avoid short circuit. * Equipment list: You will use the acquisition portable device Xplorer GLX® from Pasco. This is a handset with multiple functions capable to acquire digital signals from a variety of detectors available in the laboratory. Read carefully the quick guide to be familiar with the multiple functions of the device. Be aware of the voltage/current limits of the device you are using consulting the User’s Guide. Voltage probes are designed to measure voltages between +10V and -10V. If you are not sure about the characteristics of the equipment a complete user guide can be found in: http://pasco.com/file_downloads/product_manuals/Xplorer-GLX-Manual-PS-2002.pdf Take the following precautions:
DO NOT EXCEED THE MAXIMUM VOLTAGE OR YOU CAN DAMAGE PERMANENTLY THE Xplorer.
Resistors can get very hot when connected in a circuit. Do not touch the resistors when the circuit is closed ECE103. Spring 2012 Experiment #3 Student name(s) and lab section: Page 2 from 6 • Basic Circuit Elements: The figure below shows the symbols of the simplest circuit elements that you will use in the different laboratories during the semester • Resistor Color Bands: Carbon resistors are the most common ones, and come in a wide range of power ratings. Their resistances are identified by a color code. In addition to the resistance value, a tolerance value is included in the code. Typically carbon resistors employ 5% tolerances, and can handle ¼ W. This means that the current and voltage have to be controlled not to exceed the power ratings. On each resistor you will find 3 or 4 color bands , each color represents number, the colors which you are going to see are :- ECE103. Spring 2012 Experiment #3 Student name(s) and lab section: Page 5 from 6
Connect the voltage (Vm) and current (Im) sensors to the circuit. How should they be connected?. Remember to refer the negative terminal of the source to ground. Consult with the TA if you have doubts.
Complete the connections with the voltage source OFF. After checking the connections, make sure that the settings in the voltage source are below the maximum allowed limit (10 V). Your circuit should look like the picture above.
Utilize the +/- 6 V output of the voltage source
Remember, you should always turn off the power to a circuit while modifying it. Afterwards, you will need to turn the power back on to make the measurement. The best way to turn the power on and off to the circuit is to use the “Output On/Off” button on the power supply. This allows the voltage and current settings to remain unchanged. Practice II (20 points) - Using your circuit solving knowledge, what value of Vm do you expect across the resistor? a- Set the voltage in this source to 1 V, measure the voltage indicated by the voltage sensor and the current. b- Increase the voltage in the source is steps of 1V up to a maximum voltage of 6 V c- Change to resistor #2 and repeat the measurements indicated in a) and b). d- Complete the following table R#1 R#2 R#3 Vm [V] Im [A] Vm [V] Im [A] Vm [V] Im [A] ECE103. Spring 2012 Experiment #3 Student name(s) and lab section: Page 6 from 6 Practice III (10 points) Plot the data for the three resistors in the same graph using MATLAB. From the graph determine the best fit and the value of the resistance in each case. How this value compares with the nominal value? Resistor #1 Resistor #2 Resistor #3 Measured from the graph Nominal Practice IV (10 pints) Now that you know V and I in the circuit, find R using Ohm’s law: V= IR. How does this resistance value compare with the color band method and the value you measured using the ohmmeter? Color band method Ideal value Ohmmeter method Measured value Ohm’s law: V= IR Calculated value - Comment on your results:- ................................................................................................................................................ ................................................................................................................................................ ....................................................................................