75 Experiment 1: Breadboard Basics
Contents
1. 1 1 2 E ko T o Q oO A 40 60 Percent of Students Read the section on Ohm s law in your textbook Also read Sections 2 3 Analysis of Data Appendix C 3 3 RSR VT ANDY Board 3 4 Breadboarding and Wiring 3 5 Multimeter and 3 8 Resistors of this book Ohm s law states the relationship between the voltage V in volts across a resistor and the current I in amperes through that resistor is V IR 1 where R is the resistance in ohms This linear relationship is an approximation that has proven to be adequate for most work in electric circuit analysis You will learn in more advanced courses that the relationship is not truly linear but that depending on how and from what the resistor is made the resistance may vary with applied voltage and magnetic field There is also a significant change in resistance with temperature These effects are discussed in most solid state physics texts such as Hook and Hall 1995 PSpice allows for corrections for the temperature dependence and other effects In this experiment you will verify Ohm s law by measuring the current through a resistor as a function of the applied voltage and will verify that the measured value of the resistor is within its specified tolerance Note that all resistors provided with Lab in a Box have a 5 tolerance meaning that each resistor is within 5 of its nominal or color coded value Hook J R and H E2. ooooo ooo0o0o0 ooo0o0o0 ooooo0 ooooo ooooo ooooo oo00o0 oo000 ooo0oo0oo0 ooooo ooooo oooo0oo0 oo00o0 ooo0oo00 oo oo oo oo oo oo oo oo oo oo oo oo oo oo oo oo oo oo oo joe0 Figure 3 Breadboard measurement locations Measure the resistance within one column of the device working area This is typically from points 5 to 6 in Figure 3 Measure the resistance between nodes in the same column but which are separated by the horizontal channel This is typically from points 6 to 7 in Figure 3 Measure the resistance between horizontally separated columns in the working area This is typically from points 5 to 8 in Figure 3 Measure the resistance between rows and columns i e between the power busses and the columns in the working area This is typically from points to 5 in Figure 3 Prepare a drawing of your breadboard and mark the back plane connections as is illustrated in Figure 2 b Your drawing need not be to scale However it should show all of the rows of the board but only a sufficient number of columns to be representative For future reference save a copy of your drawing with your lab kit 12 31 2008 79 Experiment 3 Ohm s Law Developers Objectives Estimated Time for Completion Preparation Background References JB Webb KM Lai and RW Hendricks The objective of this experiment is to verify Ohm s law V O o A E o oww g N wo fk oO OD N
3. Hall 1995 Introduction to Solid State Physics 8 E New York John Wiley amp Sons 87 Experiment 3 Materials The equipment and components required to perform this experiment are e ANDY Board e Digital multimeter e 1 ea 1000 Q resistor Brown Black Red Gold e ea mystery resistor Red Black Brown Gold This resistor will be found in the bag of course specific parts Procedure Consider the circuit diagram shown in Figure 1 A voltage of 9V is applied to a series connection of the unknown resistor and a 1 KQ resistor R2 Red Black Brown Figure 1 Circuit for verifying Ohm s law Analysis 1 Identify the unknown resistor R shown in Figure 1 What value does the color scheme Red Black Brown stand for 2 Calculate the current Jas flowing through the unknown resistor and the voltage Vp across it 3 What is the purpose of the 1 kQ resistor Measurements 4 Construct the circuit shown in Figure 1 on your breadboard Note that the 9 V source is provided by the ANDY board 5 Plug the black DMM probe into COM and the red probe into V Set the switch to the lowest volts scale that will not overflow for the expected voltage 6 Measure the voltage V across the unknown resistor See Section 3 5 for good technique Make sure your polarities are correct Be sure to include your units 7 Disconnect the wire from the unknown resistor to ground wire BC 88 Ohm s Law 8 Move the red DMM pr
4. its elastic limit and thus ruin the spring To avoid this cut and strip two short pieces of wire from your wire spool Insert the wires into the breadboard at the desired locations see below and then touch your DMM test leads to the wire ends 2 Do not plug in the power supply for your breadboard while performing this experiment registers an overflow write overflow see Section 3 5 for a discussion of the DMM overflow You are trying to verify the connections in the breadboard as shown typically in the diagram It is not critical which holes you measure so long as you measure holes as typically shown in Figure 3 For busses you will get a low resistance typically about an ohm For non connected input points points not in a bus or on the same node you will get an overflow 1 Measure the resistance within one row in the power bus This is typi cally from points to 2 in Figure 3 2 Measure the resistance between vertically separated rows of power busses This is typically from points 1 to 3 in Figure 3 3 Measure the resistance between horizontally separated rows in the power busses This is typically from points 2 to 4 in Figure 3 How are the power busses in the ANDY board wired Last Revision Breadboard Basics ooooooooooooooooonooooo js oooooooonooooonoonooons ooooooooooononoooononoono ooooooooooonooono o o90000000000 o oo oo oo oo j oossoo ooooo ooooo0 ooo0oo0oo0 oo0o0o0 ooocoo
5. DY board If there is no electrical connection between the two sides you must remember to use a jumper wire to connect them if you desire to have a bus that runs the entire width of the board See e g Figures 9 and 10 The vertical columns of holes are also busses and are typically used for inserting devices and wires Notice the horizontal break or trough in the vertical columns in the middle of the breadboard In Figure 2 there is no electrical connection between the upper and lower halves The break in the vertical columns has a special purpose It provides a convenient place for inserting integrated circuit chips into the breadboard The hole spacing between the upper and lower rows on each side of the trough is exactly the pin spacing of the dual inline pins DIP of the chips used in the experiments By placing a chip so that it straddles the trough between the upper and lower halves the pins on the opposite sides of the chip are isolated from each other In placing chips and other components on the breadboard it is imperative to be sure that each pin on the device is in a separate column otherwise they will be shorted together Connections between columns must be made by the designer using wires on the component side of the board oooooonooooo0o oooooonoono GESSESESESEo seceerrerece gooo00o000cC ooo oooooonooono GEESE ESS seceerrrece ooooooooooooooooonoooonoo oooooooocooooooonoooooono oooooooooonoooononoono ooooocoooooonoooooo
6. Experiment 1 Breadboard Basics Developers Objectives Estimated Time for Completion Preparation Background KM Lai JB Webb and RW Hendricks The objective of this experiment is to measure and to draw the electrical con nections within the ANDY board breadboard V O N WO A Ow 1 N wo A 0 OQ A 2 i tT v A o 20 40 60 80 100 Percent of students Read the general descriptions of the ANDY board and the digital multimeter given in Sections 3 3 and 3 5 of this text respectively Also read the ANDY Board User Manual and Test Procedure and be sure that you have performed the entire acceptance test procedure as described therein Finally read the hand held DMM operator s manual that came with the MY 64 DMM If you are using some other DMM read the users manual that accompanied it With the exception of Experiment 2 all of the experiments described in this book will be built on a platform called a breadboard The breadboard consists of a series of holes behind which are spring contacts that make electrical connection with wires that are inserted into the holes These springs are connected together in various combinations to create electrical nodes All the wires connected to springs that are connected together will be at the same potential In this experiment you will experimentally determine which holes are connected together to create electrical nodes for the brea
7. dboard associated with your lab kit Although breadboards are manufactured by many firms there is some consistency between them However there are also some very important differences Thus it is imperative that you verify for yourself how your particular breadboard is wired Depending on the lab kit provided for your experiments this breadboard may be stand alone unpowered in which you will use batteries to provide a source of DC power all the way to fully powered lab trainer kits such as the ANDY board in which various voltage sources clocks and or function generators may be provided Regardless of these additional features the breadboard remains essentially independent of them 75 Experiment 1 A amp D BOARD Breadboard Construction 76 soseo spese sesse SESS FSHHSS SHHSS FAAS SSSHS SSSSS SESS S668 SESS SEEES saas SESS55 SHSSS SSSSS SSSS5 SSSSS s5555 Figure 1 The RSR VT Analog and Digital ANDY Trainer There is a great variety of breadboards each having a different number of col umns and with different numbers of vertically connected holes usually five or six Some have single troughs in the middle of the board and some have two troughs Some boards have all of the holes in the outer two rows connected and some have a break in the connection in the middle The student needs to be aware of these many variations and needs to be able to quickly determine how the board she is using is connected internally A
8. e scales used to measure the voltage and the current respectively 17 Using your estimate of O from step 16 and an estimate of Oop based on expt meas digit in the least significant digit of the scales used to measure the resistance perform a t test as described in Appendix C to determine if your experimental and measured values of the resistance are statistically significantly different from each other at the 95 confidence level Explain any discrepancies 89 Experiment 3 Last Revision 90 18 Following the methodology of Appendix C perform t tests to determine if your measured and experimental values of the resistance are statistically significantly different from the nominal value Are they within the tolerance of the color band on the resistor Explain 12 3 1 2008
9. obe from the V jack to the mA jack and set the DMM switch to the minimum full scale current value that will not overflow for the expected current calculated in step 2 9 Measure the current passing through the resistor by completing the circuit with the two DMM probes To do this place the red probe on node B and the black probe on node C Review Section 3 5 for the proper technique for measuring current Again make sure your polarities are correct 10 Using Ohm s law find the resistance value of the unknown resistor a expt 2 11 Remove the resistor from your circuit 12 Move the red DMM probe to the R jack and measure the resistance of the unknown resistor 13 What is the percent difference between your experimentally determined resistance in step 10 and the measured resistance value found in step 12 ive Rp A x100 3 expt 14 What is the percent difference between the experimentally determined resistance found in step 10 and the nominal resistance value found in step 1 R pom a Ropi x100 4 R som 15 Is the difference of the experimentally determined value in step 10 within 5 of the nominal value Is the difference acceptable Why or why not Error Analysis 16 Following the methodology of the propagation of errors described in Appendix C estimate the standard error of Ropt computed from Eq 2 above Assume o ando are 1 digit in the least significant digit of th
10. onoooonoo ooooonnoooonoooononoono oooooonooooonoooonoonooonono ooooonroooonooononoono oooooooooonooonoooonooono oooooooooonoooonooonoooonoono ooooonroooonoooononoono ooooonoooo oooonoonooonono Geeserseseese2no eseeeerngeecn oooooonoooo0oo0o oooooonoooono GESSSEesesoeo soeoeerreece a b Figure 2 Typical breadboard a socket layout and b socket interconnections 77 Experiment 1 References Materials Procedure 78 Lineberry R B W C Headley and R W Hendricks 2006 RSR VT ANDY Board User Manual and Test Procedure The Bradley Department of Electrical and Computer Engineering Virginia Polytechnic Institute and State University Blacksburg VA 24061 Available at http www lab in a box net The equipment and components required to perform this experiment are e ANDY board e Digital multimeter e Wire e Wire strippers Following the concepts of Figure 3 verify the electrical connections in the breadboard Be sure to orient your breadboard in the same way as the picture To measure resistance insert the red DMM test lead into the red jack on the DMM labeled with V Q and Hz Turn the DMM knob to the setting marked with the Q symbol Put the resistance setting on the lowest scale If the multimeter Notes 1 The pointed tips on the DMM test leads are too large for the holes in the breadboard If you try to force the tip into the hole you may stretch the contact spring beyond
11. typical breadboard will look similar to the picture shown in Figure 1 Note that the RSR VT ANDY trainer shown in Figure 1 has two identical breadboards an upper board and a lower board Figure 2 a shows the layout of a segment of a typical breadboard while Figure 2 b shows the wiring diagram of its backplane In both figures the top two horizontal rows and the bottom two horizontal rows of the breadboard are typically used for power busses and ground busses A bus is simply a node with multiple connection points all of which are at the same electrical potential or voltage These busses are clearly marked in Figure 1 with a red and a blue on each end of the row and with long horizontal red and blue lines The rows on the breadboards in Figure 1 are labeled with letters A B C while the columns are numbered 1 5 10 thus allowing specific identification of each node Other boards may be marked differently or may be unmarked Breadboard Basics Notice that the breaks in the busses in Figures 1 and 2 differ In Figure 1 there is a break every five holes while in Figure 2 there is a break only in the middle of the board Figure 2 b indicates that there is a break in the wiring between the two sides of the board while the blue and red horizontal lines might imply that there is no such break in the wiring in Figure 1 Thus you must determine experimentally if there is or is not a connection between the breaks on the AN
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