18CHAPTER2.RESISTIVECIRCUITSFurther ExplorationwithNI myDAQOhm's Law states that a resistor creates a proportional relationship be-tween its voltage and current u = iR where the resistance R is the pro-portionality factor.Settingtheresistor voltage to a known value andmeasuring the resulting current with an ammeter provides another wayto measure resistance. Apply this method to measure each of the four re-sistances and comparewithyourprevious results.1.Apply the NI myDAQ 5-volt source to the terminals A and D.Usethe 5V and DGND (digital ground) terminals, with 5V connected toterminal A and DGND to terminal D.2. Use the DMM voltmeter to measure the voltage u as it appears at theresistor network, and then record this value. Expect the voltage to beslightlylessthan5.0volts,andalsoexpectthatitwillvarysomewhatfrom one circuit connection to the next.3. Use the DMM ammeter to measure the currentiflowing into terminalA; record thisvalue,too.4.Calculate the effective resistance R of theresistor network from yourtwo measurements, and then compare this value to your other mea-surements.5.Repeatfor the remaining three resistance measurements
18 CHAPTER 2. RESISTIVE CIRCUITS Further Exploration with NI myDAQ Ohm’s Law states that a resistor creates a proportional relationship between its voltage and current v = iR where the resistance R is the proportionality factor. Setting the resistor voltage v to a known value and measuring the resulting current with an ammeter provides another way to measure resistance. Apply this method to measure each of the four resistances and compare with your previous results. 1. Apply the NI myDAQ 5-volt source to the terminals A and D. Use the 5V and DGND (digital ground) terminals, with 5V connected to terminal A and DGND to terminal D. 2. Use the DMM voltmeter to measure the voltage v as it appears at the resistor network, and then record this value. Expect the voltage to be slightly less than 5.0 volts, and also expect that it will vary somewhat from one circuit connection to the next. 3. Use the DMM ammeter to measure the current i flowing into terminal A; record this value, too. 4. Calculate the effective resistance R of the resistor network from your two measurements, and then compare this value to your other measurements. 5. Repeat for the remaining three resistance measurements
192.3.CURRENTANDVOLTAGEDIVIDERS(2-4)2.3Currentand VoltageDividers (2-4)Apply the concepts of voltage dividers, current dividers, and equivalentresistance to find the currents Ii to Ig and the voltages Vi to V3.I1R1W>R312V1>R2VsrcV2>R5>R413R6V3Figure2.3:CircuitforProblem2.3Usethesecomponentvalues:.VSRC = 12 V R1 = 1.0 k2, R2 = 10 k2, R3 = 1.5 k2, R4 = 2.2 k2, Rs = 4.7 k2, andR=3.3k2NIMultisimMeasurementsEnter the circuit of Figure 2.3 into NI Multisim. Use measurement probesto measure each current; use voltmeter indicators to measure each voltage.·Place components from the"Virtual Components"palette.. Place a ground symbol and attach it to the negative terminal of thevoltage source
2.3. CURRENT AND VOLTAGE DIVIDERS (2-4) 19 2.3 Current and Voltage Dividers (2-4) Apply the concepts of voltage dividers, current dividers, and equivalent resistance to find the currents I1 to I3 and the voltages V1 to V3. Figure 2.3: Circuit for Problem 2.3 Use these component values: • VSRC = 12 V • R1 = 1.0 kΩ, R2 = 10 kΩ, R3 = 1.5 kΩ, R4 = 2.2 kΩ, R5 = 4.7 kΩ, and R6 = 3.3 kΩ NI Multisim Measurements Enter the circuit of Figure 2.3 into NI Multisim. Use measurement probes to measure each current; use voltmeter indicators to measure each voltage. • Place components from the “Virtual Components” palette. • Place a ground symbol and attach it to the negative terminal of the voltage source
20CHAPTER2.RESISTIVECIRCUITS.Place a Simulate→Instruments→Measurement Probefor each current.Place a voltmeter indicator to display each voltage (see video tutorialfor details)NI Multisim video tutorials:.Find commonly-used circuit components:http://youtu.be/G6zJ8c0ja9Q.Measure DC current with a measurement probe:http://youtu.be/uz56byigymI·Measure DC voltage with a voltmeter indicator:http://youtu.be/8h2SAz9gkBANImyDAQMeasurementsBuild the circuit of Figure 2.3 on the preceding page. Use the myDAQDMM (digital multimeter) as a voltmeter to measure each of the three volt-ages; use the DMM as an ammeter to measure each of the three currents.. Measure and record the resistance of each resistor individually; dothis before you connect the resistors together.. Place the resistors to match the resistor orientations shown in Figure 2.3 on the previous page..Implement the voltage source VsRc according to the circuit diagramof Figure B.2 on page 164.. Measure VsRc with the myDAQ DMM voltmeter and adjust the po-tentiometer to set the voltage as close to12.0volts as possible.NI myDAQ video tutorials:. DMM ohmmeter:http://decibel.ni.com/content/docs/Doc-12938.DMM voltmeter:http://decibel.ni.com/content/docs/Doc-12937.DMMammeter:http://decibel.ni.com/content/docs/Doc-12939
20 CHAPTER 2. RESISTIVE CIRCUITS • Place a Simulate → Instruments → Measurement Probe for each current. • Place a voltmeter indicator to display each voltage (see video tutorial for details). NI Multisim video tutorials: • Find commonly-used circuit components: http://youtu.be/G6ZJ8C0ja9Q • Measure DC current with a measurement probe: http://youtu.be/uZ56byigymI • Measure DC voltage with a voltmeter indicator: http://youtu.be/8h2SAZ9gkBA NI myDAQ Measurements Build the circuit of Figure 2.3 on the preceding page. Use the myDAQ DMM (digital multimeter) as a voltmeter to measure each of the three voltages; use the DMM as an ammeter to measure each of the three currents. • Measure and record the resistance of each resistor individually; do this before you connect the resistors together. • Place the resistors to match the resistor orientations shown in Figure 2.3 on the previous page. • Implement the voltage source VSRC according to the circuit diagram of Figure B.2 on page 164. • Measure VSRC with the myDAQ DMM voltmeter and adjust the potentiometer to set the voltage as close to 12.0 volts as possible. NI myDAQ video tutorials: • DMM ohmmeter: http://decibel.ni.com/content/docs/DOC-12938 • DMM voltmeter: http://decibel.ni.com/content/docs/DOC-12937 • DMM ammeter: http://decibel.ni.com/content/docs/DOC-12939
212.4.WYE-DELTATRANSFORMATION(2-5)2.4Wye-DeltaTransformation (2-5)1.Find thecurrents Ii and I22. Determine the power delivered by each of the two voltage sources.R3WR2R5>R1>R4>R6WWWV1V212I1Figure 2.4: Circuit for Problem 2.4Usethesecomponent values:.Vi= 15 V and V = 15 V·Ri=3.3k2,R2=1.5k2,R3=4.7k2,R4 =5.6k2,R5 =1.0k2and R6 = 2.2 k2NI Multisim MeasurementsEnter the circuit of Figure 2.4 intoNI Multisim.Use measurement probesto measure each current, and use the wattmeter to measure the power associated with each voltage source.·Placecomponents from the"Virtual Components"palette
2.4. WYE-DELTA TRANSFORMATION (2-5) 21 2.4 Wye-Delta Transformation (2-5) 1. Find the currents I1 and I2. 2. Determine the power delivered by each of the two voltage sources. Figure 2.4: Circuit for Problem 2.4 Use these component values: • V1 = 15 V and V2 = 15 V • R1 = 3.3 kΩ, R2 = 1.5 kΩ, R3 = 4.7 kΩ, R4 = 5.6 kΩ, R5 = 1.0 kΩ, and R6 = 2.2 kΩ NI Multisim Measurements Enter the circuit of Figure 2.4 into NI Multisim. Use measurement probes to measure each current, and use the wattmeter to measure the power associated with each voltage source. • Place components from the “Virtual Components” palette
22CHAPTER2.RESISTIVECIRCUITS. Place a ground symbol and attach it to the negative terminal of thevoltage source..Place a Simulate → Instruments→ Measurement Probe for each cur-rent..Place a Simulate→ Instruments→Wattmeterfor eachvoltage source,taking care to wire the wattmeters according to the passive sign con-vention.NI Multisim video tutorials:· Find commonly-used circuit components:http://youtu.be/G6zJ8c0ja9QMeasure DC current with a measurement probe:http://youtu.be/uz56byigymI.Measure DC power with a wattmeter:http://youtu.be/-axvclpMpiuNImyDAQMeasurementsBuild the circuit of Figure 2.4 on the preceding page. Use the myDAQDMM (digital multimeter) as an ammeter to measure each of the two currents; use the DMM as a voltmeter to measure each of the two voltagesource values.. Measure and record the resistance of each resistor individually; dothis before you connect the resistors together.. Place the resistors to match the resistor orientations shown in Fig-ure 2.4 on the previous page..Use the myDAQ-15V power supply connection for the left voltagesource and the +15V power supply connection for the right voltagesource; connect AGND (Analog Ground)to the node identified bytheground symbol..Measure the actual values of Vi and V2 when connected to the circuit;expectthemtobeslightlylessthan15volts..Rememberto inserttheDMM ammeter in series between thevoltagesource and the resistor
22 CHAPTER 2. RESISTIVE CIRCUITS • Place a ground symbol and attach it to the negative terminal of the voltage source. • Place a Simulate → Instruments → Measurement Probe for each current. • Place a Simulate → Instruments → Wattmeter for each voltage source, taking care to wire the wattmeters according to the passive sign convention. NI Multisim video tutorials: • Find commonly-used circuit components: http://youtu.be/G6ZJ8C0ja9Q • Measure DC current with a measurement probe: http://youtu.be/uZ56byigymI • Measure DC power with a wattmeter: http://youtu.be/-axVClpMpiU NI myDAQ Measurements Build the circuit of Figure 2.4 on the preceding page. Use the myDAQ DMM (digital multimeter) as an ammeter to measure each of the two currents; use the DMM as a voltmeter to measure each of the two voltage source values. • Measure and record the resistance of each resistor individually; do this before you connect the resistors together. • Place the resistors to match the resistor orientations shown in Figure 2.4 on the previous page. • Use the myDAQ -15V power supply connection for the left voltage source and the +15V power supply connection for the right voltage source; connect AGND (Analog Ground) to the node identified by the ground symbol. • Measure the actual values of V1 and V2 when connected to the circuit; expect them to be slightly less than 15 volts. • Remember to insert the DMM ammeter in series between the voltage source and the resistor