Student Assignments for CL-1919-06_053052 Part 3 — Ohm’s Law Ohm’s Law and DC Circuits Trainer 95-CL-1919-06_Part3_REVA © ConsuLab Educatech Inc, 2023. Tous droits réservés. 95-CL-1919-06 Table of Contents 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada consulab.com info@consulab.com Toll-free: +1 (800) 567-0791 USA: +1 (810) 222-4525 Canada: +1 (418) 688-9067 Fax: +1 (418) 843-3444 2 Table of Contents Trainer Layout and Familiarization 3 Front Panel Component Identification 4 Electrical Component Identification 5 Electrical Accessories 6 Trainer Use and Operation 7 Warnings and Cautions 8 Student Learning Modules 9 MODULE 3 Ohm’s Law Definition and Relationships 11 SA-4 — Series Circuits 14 SA-4 — Series Circuit - Student Answer Sheet 15 SA-5 — Series Circuits with One Resistance 16 SA-5 — Series Circuit with One Resistance - Student Answer Sheet 18 SA-6 — Series Circuits with Two Resistances 19 SA-6 — Series Circuits with Two Resistances - Student Answer Sheet 22 SA-7 — Series Circuits with Two or More Resistances 23 SA-7 — Series Circuits with Two or More Resistances - Student Answer Sheet 25 SA-8 — Available Voltage Test 26 SA-8 — Available Voltage Test - Student Answer Sheet 27 SA-9 — Positive Voltage Drop Testing 28 SA-9 — Positive Voltage Drop Testing - Student Answer Sheet 29 SA-10 — Ground Side Voltage Drop Testing 30 SA-10 — Ground Side Voltage Drop Testing - Student Answer Sheet 32 SA-11 — Parallel Circuits with Two or More Resistances 33 SA-11 — Parallel Circuits with Two or More Resistances - Student Answer Sheet 35 SA-12 — Parallel Circuits Behavior 36 SA-12 — Parallel Circuit Behavior - Student Answer Sheet 39 SA-13 — Circuit Behavior in Series and Parallel Circuits 41 SA-13 — Circuit Behavior in Series & Parallel Circuits - Student Answer Sheet 43 SA-14 — Combination Series / Parallel Circuits 44 SA-14 — Combination Series / Parallel Circuits - Student Answer Sheet 46 SA-15 — Series/Parallel Circuit w/Resistance in One Ground Path Branch 47 SA-15 — Series/Parallel Circuit w/Resistance in One Ground Path Branch - Student Answer Sheet 49 3 95-CL-1919-06 Introduction consulab.com info@consulab.com Trainer Layout and Familiarization The CL-1919-06_053052 Ohm’s Law and DC Circuits Trainer contains electrical and electronic components mounted on a panel containing electrical connection receptacles where students complete the wiring of circuits. The trainer is designed to provide learning assistance in the understanding of basic Ohm’s Law concepts and also provides learning activities for student learning of basic circuit components and operation. A built-in 120VAC to 14VDC (4 A max) power supply is internally protected and is adjustable from 2-14 VDC. The front panel contains a digital display indicating the DC voltage supply available to the trainer. The CL-1919-06_053052 trainer meets CSA/UL safety requirements. The CL-1919-06 also contains a surface mounted digital multi-meter (DMM) that is powered with two AAA replaceable batteries. NOTE : Because the trainer’s power supply output is limited to 4 A, the meter’s internal 10A ammeter fuse should never need replacement. The meter is used throughout the student activities and circuit construction for electrical measure- ments and diagnostic training. CL-1919-06 Ohm’s Law and DC Circuits Trainer 95-CL-1919-06 Introduction consulab.com info@consulab.com 4 Front Panel Component Identification Front View 1. Trainer power cord receptacle, master ON/OFF switch and main fuse holder. 2. Positive (red) receptacles for circuit construction. These receptacles are only to be used with the trainer and not to be connected to any external devices as damage could result. 3. Negative (black) receptacles for circuit construction. These receptacles are only to be used with the trainer and not to be connected to any external devices as damage could result. 4. Digital Display for available trainer voltage (Displays the DC voltage that has been set by the voltage adjustment knob). 5. Power supply voltage adjustment knob (Adjusts the available DC voltage from 2-14 ± VDC). 6. Power supply safety reset button (Resets the internal protection cut-out. Push and hold until the O.L. light flashes, then release. The voltage display will read 0.000 when the O.L. lamp is on.). 7. Power supply “OVERLIMIT” indicator light (If a short circuit is created between the Positive & Negative sides of the trainer, the internal protection cut-out will trip and turn on the O.L. indicator light. It will remain on until the problem has been corrected and the RESET button is pushed). 8. PWM (Pulse Width Modulation) generator positive and negative receptacles. 9. PWM Adjustment knob (0-100% duty cycle). 10. Digital Multi-meter. Side View 1 3 2 47 6 5 9 8 10 95-CL-1919-06 Introduction consulab.com info@consulab.com 5 Electrical Component Identification 11. L1 – # 194 Bulb. 12. L2 – # 194 Bulb. 13. D1 – LED Bulb. 14. B1 – BUZZER. 15. T1 – NPN Transistor. 16. T2 – PNP Transistor. 17. D2 – Diode. 18. L3 – # 3157 LED Bulb. 19. M1 – DC Motor. 20. RL1 – ISO 5-pin Relay. 21. Electronic Flasher. 22. POT – 75Ω Potentiometer. 23. R1 – 100Ω Resistor. 24. R2 – 40Ω Resistor. 25. R3 – 20Ω Resistor. 26. R4 – 20Ω Resistor. 27. R5 – 2Ω Resistor. 28. F1 – Optional Circuit Fuse (ATC 2-3A). 29. SW1 – SPST Toggle Switch. 30. PB1 – N.O. Push Button Switch. Front View 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 95-CL-1919-06 Introduction consulab.com info@consulab.com 6 Electrical Accessories Storage Bag Main Fuse Main Fuse Specifications: Model 239002P 2A, 250V, 239 Series, Slo-Blow Fuse (5 mm x 20 mm). Storage Bag Jumper Leads CL-1919-05 POWER SUPPLY FUSE SPECIFICATIONS – 239002P 2A, 250V, 239 Series, Slo-Blow Fuse (8mm x 20mm) TRAINERS MAIN FUSE LOCATION PULL TAB AWAY UNTIL FUSE HOLDER POPS OUT CLOSE UP OF MAIN FUSE HOLDER CLOSE UP OF MAIN FUSE HOLDER SPARE FUSE FUSE IN CIRCUIT CL-1919-05 POWER SUPPLY FUSE SPECIFICATIONS – 239002P 2A, 250V, 239 Series, Slo-Blow Fuse (8mm x 20mm) TRAINERS MAIN FUSE LOCATION PULL TAB AWAY UNTIL FUSE HOLDER POPS OUT CLOSE UP OF MAIN FUSE HOLDER CLOSE UP OF MAIN FUSE HOLDER SPARE FUSE FUSE IN CIRCUIT CL-1919-05 POWER SUPPLY FUSE SPECIFICATIONS – 239002P 2A, 250V, 239 Series, Slo-Blow Fuse (8mm x 20mm) TRAINERS MAIN FUSE LOCATION PULL TAB AWAY UNTIL FUSE HOLDER POPS OUT CLOSE UP OF MAIN FUSE HOLDER CLOSE UP OF MAIN FUSE HOLDER SPARE FUSE FUSE IN CIRCUIT Your product may be equipped with either of the below jumper wire styles. They are identical in specifications and performance. All CL-1919-06’s will be shipped with banana plug jumper leads including: • 10 Red Jumper Leads — 23” (60cm) long • 10 Black Jumper Leads — 23” (60cm) long 95-CL-1919-06 Introduction consulab.com info@consulab.com 7 Trainer Use and Operation The CL-1919-06-93 manual is designed to provide instructors and students with the necessary information for the prop- er and safe operation of the trainer. Note that the CL-1919-06 trainer includes student assignments (95-CL-1919-06 ) and an instructors manual (CL-1919-06-96). Be sure to read, understand and follow the instructions for each section. The CL-1919-06 is designed to be used as a “stand alone” resource to aid the instructor and students in the learning of basic electricity, Ohm’s Law, DMM meter use, basic electrical and electronic component operation, basic operational circuit construction and diagnosis and troubleshooting of circuit problems. NOTE: Before proceeding with this manual, the following tasks should have already been successfully performed and understood: 1. Familiarization with the CL-1919-06 component layout and identification (pages 5-8). 2. The CL-1919-06 should be set up on a bench/tabletop with the cover removed, the power cord plugged into the trainer and a 120VAC outlet and the master ON/OFF switch turned “on”. NOTE- The cover lid of the trainer can be placed on a table, then move the trainer on top of the cover. This po- sitions the trainer with a slight tilt providing an easier access for users. If properly completed, the digital display should be indicating the available DC voltage. For normal operation, and unless otherwise directed, the display should be adjusted to a reading of 14.0 - 14.6 ± volts. Rating Specifications: • Voltage: 100-240 VAC, single phase • Frequency: 50/60 Hz • Input Current: 2.2 A @120 VAC, 1.2 A @ 230VAC • Output current : 2-14 VDC, 4 A max. • Indoor use only • Temperature: 10 ºC – 30 ºC (50 ºF – 86 ºF) • Humidity (non-condensing): 90 % max. • Altitude : 2,000 m (6,562 ft) • Pollution Degree 2 • Overvoltage Category II Students conducting the circuit learning assignments should have completed the following Learning Modules which contain the prerequiste skills and knowledges: • Understanding basic digital multi-meter setup, use & interpretation (Student Learning Module #1). • Basic electricity (Student Learning Module #2). • Ohm’s Law (Student Learning Module #3). • Component explanation (Student Learning Module #4) • Ability to read and follow written instructions. • Ability to read and interpret basic electrical wiring schematics. 95-CL-1919-06 Introduction consulab.com info@consulab.com 8 Warnings and Cautions Even though the power supply is internally protected against short-circuits and wiring errors, students should carefully read, understand and follow all activity instructions to avoid errors. NOTE- If the digital display shows “0.000” volts and the O.L. lamp is “on”, an overcurrent situation has been detected. To re-set the system, find and correct the wiring error, then push and hold the RESET button until the O.L. lamp flashes, then release. If the reset procedure was successfully completed, the display should read available voltage: 1. The 2-3A ATC blade type fuse on the trainer is for optional use by instructors and students as needed. Circuits can be connected with the fuse if desired. Remember that the trainer is internally protected to trip the over-current protection if current exceeds 4 A. 2. Access to fuse compartment and any other components inside of unit to be performed only by trained skilled per- sonnel. 3. L1 and L2 bulbs are made of glass and could break if impacted hard enough, therefore potentially creating a cutting hazard. 4. Do not connect any external device to be powered by the trainer as they may exceed the designed limits of the power supply and components. 5. Be sure to read, understand and follow each set of instructions. Be sure to ask your instructor if you have any ques- tions about any instruction or component. 6. Never “guess” about the results of a circuit. Always follow written instructions to avoid “guesswork”. 7. This product is intended for use in educational establishments by STUDENT OPERATORS at least 14 years of age and under the supervision of theRESPONSIBLE PERSON. 9 95-CL-1919-06 Introduction consulab.com info@consulab.com Student Learning Modules The CL-1919-06 manuals contain Student Learning Modules designed to provide information and resources to assist stu- dents in mastering various skills and knowledges covered with this trainer. Each module comes with educational support information, student activity assignments, student answer sheets, instructor keys and assessment tests. Instructors can use them as they see fit for their programs. Student answer sheets, schematics and assignments can be duplicated and distributed within the schools programs only. PDF fillable answer sheets are also available. Duplication of documents used for outside sources is prohibited. Assignment and test answer sheets can be filed in student files for record keeping of progress. It is recommended that instructors follow the chronological order of the assignments. However, each mod- ule can be presented on its own if desired. The CL-1919-06 Learning Modules 1. UNDERSTANDING THE DIGITAL MULTIMETER — SETUP, USE & INTERPRETATION 2. BASIC ELECTRICITY 3. OHM’S LAW 4. COMPONENT EXPLANATION 5. STUDENT EXPERIMENTS 6. ADVANCED STUDENT CIRCUIT ASSIGNMENTS 10 95-CL-1919-06 Module 3 — Ohm’s Law consulab.com info@consulab.com MODULE 3 Ohm’s Law 11 95-CL-1919-06 Module 3 — Ohm’s Law consulab.com info@consulab.com Definition and Relationships This section of the CL-1919-06 manual will cover Ohm’s Law basics and electrical circuit understanding. Successful tech- nicians in any electrical specialty must understand and be able to apply the concepts of Ohm’s Law when performing any electrical circuit diagnosis and repair. A lack of understanding of the relationships between volts, ohms and amps described in this manual often results in misdiagnosis of the original problem and unnecessary replacement of expen- sive components. What is ohm’s law ? A German physicist by the name of Georg Ohm (1787-1854) conducted many different experiments with electricity and around 1827, he formulated an explanation of how electricity “behaves”. Basically, Ohm’s Law describes the direct relationships that occur between voltage, amperage or current and resistance. Mr. Ohm applied mathematics to explain the relationships between the three “elements” (voltage, current and resistance) of electricity. It was previously under- stood that electricity was the flow of electrons through a conductor, but Mr. Ohm was able to explain how each element affected the other. The formula of A = V ⁄ R was his conclusion of how electricity operates in a circuit. Looking at the formula, “A” is the “intensity” or the amount of current (electrons) flowing in a circuit. “I” is expressed as INTENSITY which is the amount of current or amperage flowing in the circuit. Most sources use “A” instead of “I”. “V” is the electrical pressure pushing the electrons through the circuit. “V” is expressed in VOLTAGE or VOLTS. “R” is expressed as resistance opposing the flow of current and is expressed in OHMS or uses the symbol of the Greek Omega sign of “Ω”. Understanding how to use this information is critical to being able to diagnose electrical circuit problems. Ohm’s Law can be taught several different methods with some using extensive mathematical calculations used to “prove out” the system. For purposes of this manual, we are going to keep this section as simple as possible. Your instructor can supply additional information if needed to fully understand how to use Ohm’s Law in your learning of electrical fundamentals. Relationships A statement that explains Ohm’s Law is that : “It’s take one volt of electrical pressure to push one ampere of electrons through one ohm of resistance.” Voltage and Resistance are the primary contributory “factors” of amperage. Amperage by itself cannot be “created”, but is the result of changes in either voltage or resistance. Thinking of a water hose, if the water pressure was somehow increased, the amount of water flowing out of the hose would also increase. If the water hose became “crimped” or restricted, less water would flow from it. The increase in water flow is equal to an increase in current or amperage when the voltage or pressure is increased. Amperage is the amount of electrical flow caused from the amount of voltage and resistance in the circuit. Many instructors today find that using “voltage drop” to explain Ohm’s Law to students provides a clearer understanding that using math formula’s. It is a personal choice for each instructor. 12 95-CL-1919-06 Module 3 — Ohm’s Law consulab.com info@consulab.com Certain “rules” can be created to explain circuit performance : • If the voltage (pressure) is increased, and the resistance remains the same, the amperage (flow) will also increase. This is because there is a stronger amount of “push” pushing the electrons through the same resistance which re- sults in more electrical flow. • If the voltage (pressure) is decreased, and the resistance remains the same, the amperage (flow) will also decrease. Less pressure will reduce the flow of electrons because there is less “push” causing the electrons to move. • If the resistance (ohms) increases, and the voltage remains the same, the amperage (flow) will decrease. If we in- crease the amount of restriction to flow, the flow will decrease. Think of crimping the water hose a bit. What hap- pens ? Less water comes out. • If the resistance (ohms) decreases, and the voltage remains the same, the amperage (flow) will increase. If we cause the resistance to go down, more flow will result. Increasing the size of the water hose would result in more water flowing from it. • If both resistance (ohms) and voltage (pressure) increase, the amperage (flow) will also increase. • If both resistance (ohms) and voltage (pressure) decrease, the amperage (flow) will also decrease. Using ohm’s law to understand “circuit behavior” Anyone diagnosing electrical circuit problems must understand the concepts of Ohm’s Law and be able to apply them to an abnormally behaving circuit in order to determine the source of the fault. For a specific example, suppose that a ve- hicle headlight operated dimly when turned on. A dim headlight indicates that the amperage flow in the headlight circuit is less than designed amounts. What would cause a reduction of circuit amperage ? Remembering Ohm’s Law, either an increase in resistance or a reduction of voltage would cause this condition. If the vehicles operating voltage remains unchanged, then the problem must be an increase in a resistance somewhere in the circuit. This unwanted increase in resistance could be in either supply (positive) side or the ground (negative) side of the circuit. The technician would then test for the unwanted resistance until it was found. Common sources of unwanted increased resistance in headlight circuits could be corrosion, rust, dirty electrical terminals and corroded wires. With Ohm’s Law if any two of the three circuit values (volts, amps or ohms) are known, you can calculate the third unknown value. We can use formulas to assist us when we calculate for the unknown value. For the purposes of this manual, we will use the following abbreviations for : Ohms = R, Amps = A and Voltage = V. To calculate OHMS : R = V ⁄ A To calculate AMPS : A = V ⁄ R R V A To calculate VOLTS : V = A × R An easier method to remember the above formulas is to visualize the formulas in a circle as shown. To use this shortcut, simply place your finger over the value you wish to calculate and perform the math that shows in the remaining display. For example, if you wish to calculate for resistance, place your finger over the R. What is left is to divide VOLTAGE by AMPS. This calculation would result determining the OHMS value. 13 95-CL-1919-06 Module 3 — Ohm’s Law consulab.com info@consulab.com Example : If the blower motor has a resistance of 2 ohms, how many amps will it “draw” when running on “high” speed with an operating voltage of 14.5 volts ? Answer : 7.25 amps 14.5 V ⁄ 2 Ω = 7.25 A In recent years, many instructors no longer use complicated math formulas to teach Ohm’s Law to students, but instead discuss and measure the voltage drop across each resistance. Voltage drop measurements tend to give students more related knowledge of how electrical circuits “behave”. Explanations and activities of VOLTAGE DROP will be covered in upcoming sections. Electrical circuit What is an Electrical Circuit ? A typical automotive electrical circuit contains the following : • A source of voltage (usually the battery). • Some type of overcurrent protection (fuse, circuit breaker or fusible link). • Usually a type of switch (to control when the circuit is on. The switch can be on either the positive or negative side of the circuit. • Some type of resistance that performs a useful purpose (light bulb, motor, horn, etc.). This resistance is commonly called the LOAD in the circuit. • Positive wires that allow current to flow from the battery to the resistance. • Ground wires that allow current to flow from the resistance back to the battery. Types of circuits in automotive electrical systems The modern automobile contains three basic types of electrical circuits. They are : 1. Series circuit 2. Parallel circuit 3. Combination series/parallel circuit It is important for the technician to understand all three types of circuits and how volts, amps and ohms “behave” in each. This understanding is CRITICAL in being able to understand, diagnose and repair electrical circuits on today’s complex vehicle systems. After completion of this section, ask your instructor for Test 6. 14 95-CL-1919-06 Module 3 — SA-4 consulab.com info@consulab.com SA-4 — Series Circuits SA-4 — Circuit Explanation A series circuit is defined as having just one single path that electricity can flow. The circuit will have positive and nega- tive wires connected from the voltage source to a resistance located between them. The important thing to remember about a series circuit is that a break (open) occurring anywhere in a series circuit will cause the entire circuit to shut off or not operate. A series circuit can have more than one resistance, but normally has only one. Volts, Amps and Ohms and their relationship to each other “behave” or perform in predictable ways in a series circuit. In the following steps, you will construct some series circuits on the trainer to further learn how series circuits operate. Be sure to carefully read, understand and follow the written instructions for the trainer wiring exercises. Use the student answer sheet for SA-4 SERIES CIRCUIT ASSIGNMENTS to record all of your measurements and question answers.This circuit is a SERIES circuit because there in only one path for current to flow. Also, this circuit has only one resistance (bulb L1). The overcur- rent device is fuse F1 and the control device is switch SW1. Turning SW1 on and off should cause the bulb to switch on and off. Most of the circuits used in the automobile are series circuits. F1 SW1 L1 BLK GND14.00-14.60 V SA-4 — Procedure : Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-4 student answer sheet to record all of your measurements and question answers. A. Make sure the CL-1919-06 trainer is properly set up and is plugged in to a 120V receptacle. B. Turn the CL-1919-06 master power switch ON. The voltage display should be on. Adjust the voltage adjustment knob until the voltage displayed is 14.00-14.60 volts. C. Connect RED jumper wires to the following locations : A. Any of the four RED + power terminals of the trainer to left-hand yellow terminal of the F1 fuse. B. The right-hand yellow terminal of fuse F1 to terminal O of switch SW1. C. Terminal I of switch SW1 to terminal A of bulb L1. D. Connect BLACK jumper wires to the following locations : A. Terminal B of bulb L1 to any of the BLACK ground terminals on the trainer. B. Draw the circuit you have just constructed on a blank trainer schematic sheet and label it : SA-4 SERIES CIR- CUIT WITH ONE RESISTANCE, that will also serve for SA-5 assignment. E. Confirm the correct hookup of this circuit your instructor. 15 95-CL-1919-06 Module 3 — SA-4 consulab.com info@consulab.com SA-4 — Series Circuit Operation With a series circuit, a break or “open” anywhere in the circuit whether on the “positive” or “negative-ground” side will cause the entire circuit to be inoperative. To confirm this, perform the following steps with the bulb L1 on : 1. Temporarily disconnect either end of any of the RED jumper wires (positive). Describe the circuit performance on the answer sheet. 2. Temporarily disconnect either end of the BLACK jumper wire (negative or ground). Describe the circuit performance on the answer sheet. SA-4 — Series Circuit - Student Answer Sheet Name : Group : Date : 1. Describe the circuit performance : 2. Describe the circuit performance : Instructor grade : Comments : 16 95-CL-1919-06 Module 3 — SA-5 consulab.com info@consulab.com SA-5 — Series Circuits with One Resistance SA-5 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-5 student answer sheet to record all of your measurements and question answers. 1. Start with the circuit turned OFF. 2. Disconnect any RED wire from the circuit and install the RED and BLACK ammeter leads at the two connections the RED wire was removed from. This puts the ammeter in “series” with the circuit. Make sure meter has been adjusted to read amperage. 3. Turn on the circuit by operating SW1 and read the amperage of the bulb L1. Use the answer sheet. 4. Turn switch SW1 off. 5. Disconnect the DMM test leads 6. Connect the DMM to properly measure amperage in the ground side of the circuit. Connecting the DMM at either end of the BLACK wire is correct. 7. Turn on switch SW1 and measure the ground side amperage. Use the answer sheet. 8. Turn switch SW1 off and disconnect the meter test leads. Reconnect jumper wires for correct circuit operation. CONCLUSIONS : The amperage in a series circuit is the same in all parts of the circuit. This is because there is only one path for the current to flow. 9. Setup the DMM to measure voltage. 10. Turn switch SW1 to the on position. 11. Measure voltage between any of the four RED power receptacles and any of the four BLACK ground receptacles. Use the answer sheet. 12. Measure the voltage at bulb L1 between the positive and ground terminals and record on the student answer sheet. CONCLUSIONS : In a series circuit with only one resistance, all of the source (battery) voltage is available to the resis- tance. 17 95-CL-1919-06 Module 3 — SA-5 consulab.com info@consulab.com SA-5 — Calculating Resistances Using Ohm’s Law Light bulb resistances can be measured with the current not flowing in the bulb (static) and the amount of current flowing when the bulb is on (dynamic) can be calculated using Ohm’s Law. Light bulb static and dynamic resistances will not be the same because the internal resistance of the light bulb increases with the heat created during illumination. Let’s determine the static and dynamic resistance of bulb L1. 13. Turn SW1 off. 14. Set up the DMM to measure resistance. 15. With the circuit off, measure the resistance of bulb L1 and record your measure on the student answer sheet. NOTE- the resistance of bulb L1 will slowly drop as the bulb cools off. Wait until ohmmeter stabilizes. 16. Using Ohm’s Law, calculate the bulb L1’s dynamic resistance and record your reading on the student answer sheet. To calculate an incandescent light bulbs “dynamic” resistance and using Ohm’s Law, divide the bulbs current into the source voltage. The answer will be the dynamic resistance in ohms. 17. Answer the question, “Why are the static and dynamic bulb resistances different between being OFF and ON ?” To complete these next assignments, you will need to have the current flow through bulb L1 and the voltage applied to it that you obtained from previous steps. Put your answer on the answer sheet. 18 95-CL-1919-06 Module 3 — SA-5 consulab.com info@consulab.com SA-5 — Series Circuit with One Resistance - Student Answer Sheet Name : Group : Date : 3. amps on positive side of circuit. Expressed as : 7. amps on negative side circuit. Expressed as : 11. volts between positive and ground test receptacles. Expressed as : 12. volts between positive and ground terminals of L1. Expressed as : 15. ohms of static resistance of L1 (off). Expressed as : 16. ohms of dynamic resistance of L1 (on). Expressed as : 17. Instructor grade : Comments : 19 95-CL-1919-06 Module 3 — SA-6 consulab.com info@consulab.com SA-6 — Series Circuits with Two Resistances SA-6 — Circuit Explanation A series circuit has only one path for current to flow, but can have more than one resistance in it. Having two or more resistances will affect the operation of the entire circuit. Many circuit problems are caused by “unwanted” resistances being present in a circuit that is designed to have only one resistance. In the case of light bulbs, having unwanted resistance will cause the bulb to operate will less brilliance than design which results in a “dim bulb” operation. F1 SW1 R1 L1 BLK GND 14.00-14.60 V NOTE- This schematic uses symbols for light bulbs, but each represents a resistance in the series circuit and could also be a resistor instead of a bulb. SA-6 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-6 student answer sheet to record all of your measurements and question answers. 1. Start with all jumper wires disconnected from the trainer. 2. Connect RED jumper wires to the following terminals : A. Any of the four RED + receptacles on the trainer to the left-hand yellow terminal of fuse F1. B. The right-hand yellow terminal of fuse F1 to terminal O of switch SW1. C. Terminal I of switch SW1 to terminal K of resistor R1. D. Terminal J of resistor R1 to terminal A of bulb L1. 3. Connect a BLACK jumper wire to the following terminals : A. Terminal B of bulb L1 to any of the four BLACK ground receptacles on the trainer. 4. Draw the circuit you have just constructed on a blank trainer schematic sheet and label the schematic : SA-6 SERIES CIRCUIT WITH TWO RESISTANCES. 5. Turn switch SW1 on and observe the operation of bulb L1. Describe circuit operation on the answer sheet. 6. Measure the voltage that is present at terminals A and B of bulb L1. Most technicians describe this voltage as the “voltage drop” across the light bulb. Record your reading on the answer sheet. 7. Measure the voltage that is present at terminals J and K of resistor R1. Most technicians describe this voltage as the “voltage drop” across the resistor. Record your reading on the answer sheet. 20 95-CL-1919-06 Module 3 — SA-6 consulab.com info@consulab.com 8. Measure the voltage that is present between any of the RED positive receptacles and any of the four BLACK ground receptacles. Technicians would describe this reading as the “total voltage drop” of the circuit. Record your reading on the answer sheet. 9. Add the readings from steps 6 and 7 together and record your answer on the answer sheet. CONCLUSIONS : There are two resistances in this series circuit. One is bulb L1 and the other is resistor R1. Because there is only one path for current to flow, the current must flow through resistor R1 and bulb L1 on its way to ground. Because it takes a portion of the total available current to push electrons through the resistor, there will be less avail- able to operate the bulb. That is why the bulb is dim. As voltage is the electrical pressure pushing electrons through resistances, some voltage is used to push electrons through both the resistor and the bulb. How much voltage is used is determined by the value of each resistance. Higher resistances require more voltage to push electrons through them. 10. Measure the current flowing in the circuit by installing your DMM setup to read amperage. You can install the DMM anywhere in the circuit to measure amperage because it is a series circuit. Record your reading on the answer sheet. 11. Using Ohm’s Law, calculate the value of the resistor and the bulb in this circuit (Remember the resistance of the bulb is based on its temperature and thus will be different operating dimly than when operating at full brilliance.). A. Value of resistor R1 calculated using Ohm’s Law. B. Value of bulb L1’s dynamic resistance calculated using Ohm’s Law. 12. Turn the circuit off and using the DMM setup to measure resistance, measure the value of R1 and record on answer sheet. Don’t forget to change the function switch of the meter from amps to ohms. 13. The calculated value of R1 from step #12 and the measured value of R1 from step #14 should be very close to equal. Are they about equal ? Yes or No. Indicate your answer on the answer sheet. If not, go back over your work to determine where you made errors. SA-6 — Variation of Resistance Locations In the previous experiment, the resistor was located on the “positive” side of the circuit and caused the bulb to be “dimmer” than normal. Now, we will install the resistor on the ground side of the circuit and evaluate circuit performance. 14. Start with all jumper wires disconnected from the trainer. 15. Connect RED jumper wires to the following terminals : A. Any of the four RED + power terminals of the trainer to left-hand yellow terminal of the F1 fuse. B. The right-hand yellow terminal of fuse F1 to terminal O of switch SW1. C. Terminal I of switch SW1 to terminal A of bulb L1. 16. Connect BLACK jumper wires to the following locations : A. From terminal B of bulb L1 to terminal J of resistor R1. B. From terminal K of resistor R1 to any of the four BLACK ground receptacles on the trainer. 21 95-CL-1919-06 Module 3 — SA-6 consulab.com info@consulab.com 17. Draw the circuit you have just constructed on a blank trainer schematic sheet and label the schematic : SA-6 VARIA- TION OF RESISTANCE LOCATIONS. 18. Before turning on the trainer, predict what the circuit performance will be with the resistance located in the ground side of the circuit and record your answer on the answer sheet. 19. Turn on the trainer and evaluate circuit performance. Describe on the answer sheet. 20. Using the DMM setup to measure amperage, measure the total circuit amperage anywhere in the circuit and record your reading on the answer sheet. 21. Using the DMM setup to measure voltage, measure the voltage drop across bulb L1 and record on answer sheet. 22. Using the DMM setup to measure voltage, measure the voltage drop across the resistor R1 and record on answer sheet. CONCLUSION : In a series circuit, adding another resistance affects the performance of the entire circuit. “Unwanted” resistances can be located either on the positive or negative sides of the circuit or both and will have identical effects on circuit performance. 22 95-CL-1919-06 Module 3 — SA-6 consulab.com info@consulab.com SA-6 — Series Circuits with Two Resistances - Student Answer Sheet Name : Group : Date : 5. 6. volts available to bulb L1. Expressed as : 7. volts available to resistor R1. Expressed as : 8. volts available at POS & GND terminals. Expressed as : 9. voltage drop of bulb L1 & resistor R1 added together. Expressed as : 10. amps flowing in the circuit. Expressed as : 11. A. ohms of R1. Expressed as : B. ohms of L1. Expressed as : 12. ohms of R1. Expressed as : 13. Yes or No. 18. Your prediction of circuit performance (OFF) 19. Description of circuit performance (ON) 20. amps of total circuit Expressed as : 21. voltage drop across bulb L1. Expressed as : 22. voltage drop across resistor R1. Expressed as : Instructor grade : Comments : 23 95-CL-1919-06 Module 3 — SA-7 consulab.com info@consulab.com SA-7 — Series Circuits with Two or More Resistances SA-7 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-7 student answer sheet to record all of your measurements and question answers. 1. Start with all jumper wires disconnected from the trainer. 2. Connect RED jumper wires to the following terminals : A. Any of the four RED + power terminals of the trainer to left-hand yellow terminal of the F1 fuse. B. The right-hand yellow terminal of fuse F1 to terminal O of switch SW1. C. Terminal I of SW1 to terminal M of resistor R2. D. Terminal L of resistor R2 to terminal A of bulb L1. 3. Connect BLACK jumper wires to the following locations : A. Terminal B of bulb L1 to terminal J of resistor R1. B. Terminal K of resistor R1 to any of the four BLACK ground receptacles on the trainer. 4. Draw the circuit you have just constructed on a blank trainer schematic sheet and label the schematic : SA-7 SERIES CIRCUIT WITH TWO OR MORE RESISTANCES. 5. Predict circuit performance before turning on the power. Record your prediction on the answer sheet. 6. Turn on the trainer and evaluate circuit performance. Record the description of the circuit on the answer sheet. 7. Using a DMM setup to measure amperage, measure the total circuit amperage of this circuit and record on the an- swer sheet. 8. Using a DMM setup to measure voltage, measure the voltage drop across the following components and record your readings on the answer sheet : A. Resistor R2. B. Bulb L1 C. Resistor R1 9. Add the voltage drops of all three components together and record on answer sheet. The sum should be almost equal to the source voltage of about 14.6 volts (depending on what the trainers voltage display shows as total voltage) 10. Do not disassemble this circuit yet as it will be needed for further experiments. 24 95-CL-1919-06 Module 3 — SA-7 consulab.com info@consulab.com CONCLUSIONS : In this circuit, there are three resistances. One of the bulb L1, one is the resistor R2 located on the pos- itive side of the circuit and the last is R1 located in the ground side of the circuit. All three are connected in series. The “behavioral laws” of series circuits are as follows : A. Each added resistance will reduce total circuit amperage. B. The amperage in a series circuit will be the same throughout all parts of the circuit. C. Total circuit resistance is equal to the sum of the individual resistances. D. Each resistance will have a voltage drop across it that can be measured. E. The sum of all individual voltage drops will equal the source voltage. SA-7 — Application of Learned Concepts Because many of the circuits used on automobiles are series circuits, it is important that you understand the operating characteristics in order for you to properly and efficiently be able to diagnose and repair malfunctioning circuits. When evaluating a series circuit with problems, most technicians use voltage drop testing to help them locate the source of the unwanted resistance. Checking voltage drops from one accessible point to another helps in pinpointing the source of the problem. Here are some tips and suggestions for troubleshooting series circuits : • If possible, measure the available voltage to the component in the circuit. For example, measure the voltage avail- able at the blower motor, the headlight, the power window motor, etc. • If the voltage is lower than the source voltage and the component is designed to operate on full source voltage, there may be unwanted resistance located in either the positive or ground sides of the circuit. • The next assignments would be to determine if the unwanted resistance is in the positive or negative portions of the circuit. Assignment SA-8 will conduct an “available voltage test” in the circuit. 25 95-CL-1919-06 Module 3 — SA-7 consulab.com info@consulab.com SA-7 — Series Circuits with Two or More Resistances - Student Answer Sheet Name : Group : Date : 5. Your prediction of circuit : 6. Actual circuit performance : 7. amps of circuit Expressed as : 8. A. voltage drop across R2 Expressed as : B. voltage drop across L1 Expressed as : C. voltage drop across R1 Expressed as : 9. total voltage drops Expressed as : Instructor grade : Comments : 26 95-CL-1919-06 Module 3 — SA-8 consulab.com info@consulab.com SA-8 — Available Voltage Test SA-8 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-8 student answer sheet to record all of your measurements and question answers. 1. Use the SA-7 SERIES CIRCUIT WITH TWO OR MORE RESISTANCES circuit (steps #1-10), (one most recently con- structed) conduct an available voltage test to bulb L1. 2. Connect the DMM setup for measuring voltage to terminals A and B of bulb L1. In this test we are measuring “avail- able voltage” to the bulb. In a normally operating circuit, it should equal the source voltage which in this case is approximately 14.6 volts (may vary depending trainer component variations). 3. Turn on the trainer and record available voltage at the bulb. Record your measurement on the answer sheet. 4. A normally operating circuit should have very close to source voltage available to the device (if it is designed to operate at full source voltage). Less than source voltage indicates unwanted resistance somewhere in either the positive side or negative side of the circuit. 5. With the voltmeter still connected at bulb L1 as before, using jumper wires and the piggy-back feature of the con- necters, temporarily bypass resistors R1 and R2 by connecting jumper wires from terminals J & K of resistor R1 and terminals L & M of resistor R2. 6. Measure the available voltage with both jumpers installed and record on answer sheet. 7. Remove both jumper wires from resistors R1 and R2. CONCLUSIONS : With the resistances installed in both the positive and ground sides of the circuit, the available voltage to bulb L1 was much less than source voltage. As soon as the resistors were “bypassed”, the available voltage went up to normal readings. Any available voltage reading less than source voltage indicates unwanted resistance causing a voltage drop somewhere in the circuit. Checking available voltage at the device doing the designed function in the circuit (motor, bulb, etc) is a good way of determining if there is unwanted resistance in the circuit. Available voltage should be very close to source voltage on devices designed to operate at full source voltage. WARNING : Be sure to measure source voltage first before performing this test as a partially discharged battery could provide a lower than normal source voltage reading. Try to keep the trainers display voltage as close to 14.00 as possi- ble. This is a very sensitive adjustment. Normal source voltages for non-running vehicles is approximately 12.6 volts and between 13.5-14.9 volts on running vehicles. After completion of SA-8, turn in your answer sheet to the instructor and ask for Test 7 before proceeding to the next assignment. 27 95-CL-1919-06 Module 3 — SA-8 consulab.com info@consulab.com SA-8 — Available Voltage Test - Student Answer Sheet Name : Group : Date : 3. volts at L1 Expressed as : 6. volts at L1 with resistors bypassed Expressed as : Instructor grade : Comments : 28 95-CL-1919-06 Module 3 — SA-9 consulab.com info@consulab.com SA-9 — Positive Voltage Drop Testing F1 BLK GND SERIES CIRCUIT WITH TWO OR MORE RESISTANCES 14.00-14.60 V SA-9 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-9 student answer sheet to record all of your measurements and question answers. 1. Using the SA-7 SERIES CIRCUIT WITH TWO OR MORE RESISTANCES circuit from above (steps #1-10), (one most recently constructed) conduct a voltage drop test of the positive side of the circuit. 2. Using a DMM setup to measure voltage, measure the voltage drop from terminal A of bulb L1 to any of the four RED positive receptacles on the trainer. Record your reading on the answer sheet. 3. What should the voltage drop reading be if the positive side of the circuit is operating normally without faults ? An- swer on the answer sheet. 4. What does the reading you measured seem to indicate ? Answer on answer sheet. 5. Using a RED jumper wire and using the piggy-back feature of the connecters, temporarily connect it from terminal L to terminal M of resistor R2. This in effect, bypasses the resistor in the circuit with the jumper wire which removes the resistance from the circuit. 6. With the jumper wire installed, measure the voltage drop of the positive circuit as you did in step #2. Record your reading on the answer sheet. CONCLUSION : With the jumper wire installed, resistor R2 which is located in the positive half of the circuit is “by- passed” and therefore is not in the circuit. The voltage drop should have dropped to almost zero which indicates a normally operating positive half of the circuit. Any voltage reading more than zero indicates unwanted resistance in the circuit. Checking the available voltage and voltage drops of both the positive and negative sides of the circuit at the controlled device is a very handy way of helping you determine the location of problems from unwanted resistance. 29 95-CL-1919-06 Module 3 — SA-9 consulab.com info@consulab.com SA-9 — Positive Voltage Drop Testing - Student Answer Sheet Name : Group : Date : 2. volts to positive of L1 Expressed as : 3. 4. 6. volts to positive of L1 with resistor bypassed Expressed as : Instructor grade : Comments : 30 95-CL-1919-06 Module 3 — SA-10 consulab.com info@consulab.com SA-10 — Ground Side Voltage Drop Testing SA-10 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-10 student answer sheet to record all of your measurements and question answers. 1. Turn switch SW1 OFF and remove the DMM from the circuit. 2. Remove the RED jumper wire from terminal A of bulb L1 and from terminal L of resistor R2. 3. Remove the end of the RED jumper wire that was connected to terminal M of resistor R2 and connect it to terminal A of bulb L1. There should now be NO resistances in the positive side of this circuit. 4. Turn switch SW1 to ON and describe the circuit performance in your own words on answer sheet. 5. Perform a voltage drop test of the ground circuit by connecting the RED voltmeter lead to terminal B of bulb L1 and BLACK voltmeter lead to the same BLACK receptacle used for this circuit. Record your reading on answer sheet. 6. Turn switch SW1 to OFF. 7. Evaluate the voltage drop reading you measured from Step 11. What does it mean to you ? Record your answer on the answer sheet. SA-10 — Identifying the Exact Location of the Unwanted Resistance 8. Connect the RED lead of the voltmeter to terminal B of bulb L1 and the BLACK lead of the voltmeter to terminal J of resistor R1. You are measuring the voltage drop of the BLACK ground wire from the bulb to the resistor. Put your voltage reading on your answer sheet 9. Now, connect the BLACK lead of the voltmeter to the ground receptacle that the circuit BLACK wire coming from resistor R1 is connected to and the RED lead of the voltmeter to terminal K of resistor R1. You are measuring the voltage drop of the BLACK ground wire from the resistor to system ground. Put your voltage reading on your answer sheet. Remove the DMM. 10. Evaluate both readings from Steps 13 and 14 and list your conclusions on the answer sheet. Remove the voltmeter. 11. Measure the voltage drop across resistor R1 (RED voltmeter lead to terminal J of resistor R1 and RED voltmeter lead to terminal K of resistor R1) and record your answer on the answer sheet. Remove the DMM. 12. You have completed a three point voltage drop test of the ground circuit. Your readings when correctly understood will exactly pinpoint the location of the unwanted resistance. 13. What was the location of the unwanted resistance in the ground circuit ? Record your answer on the answer sheet. 14. Remove the end of the BLACK wire connected to terminal K of resistor R1 and connect it (piggy back) to terminal J of resistor R1. 15. Connect RED voltage meter lead to terminal B of bulb L1 and BLACK voltmeter lead to the ground receptacle used for the circuit. Measure the total ground circuit voltage drop and record your reading on the answer sheet. 31 95-CL-1919-06 Module 3 — SA-10 consulab.com info@consulab.com 16. You should now be able to use voltage drop testing to locate unwanted resistance in both positive and ground cir- cuits. 17. Turn switch SW1 OFF and remove all wires and DMM wires from the trainer. Turn in your answer sheet to instructor. CONCLUSIONS : With the jumper wire installed, resistor R1 which is located in the ground half of the circuit is “by- passed” and therefore is not in the circuit. The voltage drop should have dropped to almost zero which indicates a normally operating ground half of the circuit. Any voltage reading more than zero indicates unwanted resis- tance in the ground circuit. After completion of SA-10, turn in your answer sheet to the instructor and ask for Test 8 before proceeding to the next assignment. 32 95-CL-1919-06 Module 3 — SA-10 consulab.com info@consulab.com SA-10 — Ground Side Voltage Drop Testing - Student Answer Sheet Name : Group : Date : 4. 5. voltage drop of the ground circuit Expressed as : 7. 8. voltage drop of one BLACK wire Expressed as : 9. voltage drop of one BLACK wire Expressed as : 10. 11. voltage drop of resistor R1 Expressed as : 13. 15. voltage drop of ground circuit Expressed as : Instructor grade : Comments : 33 95-CL-1919-06 Module 3 — SA-11 consulab.com info@consulab.com SA-11 — Parallel Circuits with Two or More Resistances SA-11 — Parallel Circuits Explanation A parallel circuit is defined as two or more resistances connected to a voltage source in such a way that each one re- ceives full source voltage and a ground. In a parallel circuit with two resistances, there are two paths for current to flow and a break in one of the paths still allows the other resistance to operate. In a parallel circuit, the current is “branched” or split into each of the resistances. The individual resistances can share a common ground and/or voltage feed circuit. A common example of a parallel circuit is a headlight circuit that has a left and right headlight. The circuit is fed with a single power wire from the switch, but the circuit then “splits” to feed each light with a full 12 volts. Both headlight ground circuits are individual at the headlight, but often combine to a single ground point. With a parallel circuit, the left headlight can be removed or become defective and the right headlight will still work. A break in one branch of a parallel circuit will have no effect on the other branches SW1F1 BLK GND PARALLEL CIRCUITS WITH TWO OR MORE RESISTANCES L1 L2 L3 LO 14.00-14.60 V Volts, Amps and Ohms and their relationship to each other “behave” or perform in predictable ways in a parallel circuit. In the following assignments, you will construct some parallel circuits on the trainer to further learn how parallel circuits operate. SA-11 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-11 student answer sheet to record all of your measurements and question answers. 1. Make sure the CL-1919-06 trainer is properly set up and is plugged in to a 120V receptacle. 2. Turn the CL-1919-06 master power switch ON. The voltage display should be on. Adjust the voltage adjustment knob until the voltage displayed is 14.00-14.60 volts. 3. Connect RED jumper wires to the following locations : A. Any of the four RED + power terminals of the trainer to left-hand yellow terminal of the F1 fuse. B. The right-hand yellow terminal of fuse F1 to terminal O of switch SW1. C. Terminal I of switch SW1 to terminal A of bulb L1. D. Terminal I of switch SW1 (piggy-back) to terminal C of bulb L2. 4. Connect BLACK jumper wires to the following locations : A. Terminal B of bulb L1 to any of the BLACK ground terminals on the trainer. 34 95-CL-1919-06 Module 3 — SA-11 consulab.com info@consulab.com B. Terminal B of bulb L1 (piggy-back) to terminal D of bulb L2. NOTE : This is a “shared” or common ground path for both bulbs and is a very common method of circuit construction in automobiles. 5. Draw the circuit you have just constructed on a blank trainer schematic sheet and label the schematic : SA-11 PAR- ALLEL CIRCUIT WITH TWO OR MORE RESISTANCES. 6. Confirm the correct hookup of this circuit with your instructor. 7. Turn SW1 to the on position. Both bulbs L1 and L2 should be on at full brilliance. Confirm proper circuit operation. NOTE : in the previous assignments on series circuits, specific instructions were given regarding making measure- ments of voltage, resistance and current. For these assignments, less detail will be given. If needed, refer to previ- ous assignments for more detail on meter setup and use. 8. Measure the current flow of bulb L1 at the positive side of the bulb. Record your reading on the answer sheet. 9. Measure the current flow of bulb L2 at the positive side of the bulb. Record your reading on the answer sheet. 10. Now measure the current in the ground path of both L1 and L2 bulbs. Record your reading on the answer sheet. 11. What conclusions can you make about the ground circuit of this circuit ? Put your answer on the answer sheet. 12. With the circuit turned on, temporarily remove one end of each RED jumper wire one at a time connecting to termi- nals A and C of bulbs L1 and L2. Describes what happens on the answer sheet. Turn switch SW1 OFF 13. Using the current and voltage measurements from the previous measurements, calculate the “dynamic” bulb resis- tances of L1 and L2. Put your answers on the answer sheet. 14. What is your prediction of total circuit amperage and total circuit resistance if another bulb is added in parallel to this circuit ? Put your answer on the answer sheet. 15. Add L3 LO bulb in parallel to this circuit by connecting another RED wire from terminal I of switch SW1 to the LO terminal of bulb L3. 16. Connect a BLACK wire from the COM terminal of bulb L3 to any of the BLACK ground receptacle on the trainer. 17. Turn switch SW1 to ON and confirm that all three bulbs are on at full brilliance. If not, go back over your work and correct the problem. 18. Measure the current flowing through bulb L3 LO and record on the answer sheet. 19. Using the L3 LO current and system voltage, calculate the dynamic resistance of bulb L3 LO. Fill in answer sheet. 20. Measure the total circuit current and record your measurement on the answer sheet. 21. Using your previous measurements, calculate the total dynamic resistance of the total circuit. Fill in answer sheet. 22. Describe what happens to a parallel circuit current and resistance as more resistance is added to the circuit. Fill in your answer sheet with your prediction. 23. Turn circuit OFF and trainer OFF, remove DMM and all RED and BLACK wires from trainer. Turn in your answer sheet to your instructor. CONCLUSIONS : Step #11 confirms that in a parallel circuit, each branch is individually connected to source voltage and is “independent” of other branches. In parallel circuits, as more branches are added, the “total” current flow increases, but the current flow in each branch is determined by the amount of the resistance in that branch. So, as more resistanc- es are added to parallel circuits, the “total” circuit resistance of all branches must be reduced. This is because more current is flowing as branches are added. Considering Ohm’s Law, the only way to get more current is to either decrease resistance or increase voltage. In this assignment, the voltage is constant, so the resistance is lowered as more parallel branches are added. 35 95-CL-1919-06 Module 3 — SA-11 consulab.com info@consulab.com SA-11 — Parallel Circuits with Two or More Resistances - Student Answer Sheet Name : Group : Date : 8. amps of L1 on positive half Expressed as : 9. amps of L2 on positive half Expressed as : 10. amps of L1 & L2 on ground half Expressed as : 11. 12. 13. A. ohms of dynamic resistance of L1 Expressed as : B. ohms of dynamic resistance of L2 Expressed as : 14. 18. amps of L3 LO Expressed as : 19. ohms of dynamic resistance of L3 LO Expressed as : 20. amps of total circuit (L1, L2 & L3 LO) Expressed as : 21. ohms of dynamic resistance of L1, L2 & L3 LO Expressed as : 22. Instructor grade : Comments : 36 95-CL-1919-06 Module 3 — SA-12 consulab.com info@consulab.com SA-12 — Parallel Circuits Behavior SA-12 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-12 student answer sheet to record all of your measurements and question answers. 1. Start with all RED and BLACK wires removed from the trainer. 2. Connect RED jumper wires to the following locations : A. Any of the four RED positive receptacles to the left-hand terminal of fuse F1. B. Right-hand terminal of fuse F1 to terminal O of switch SW1 C. Terminal I of switch SW1 to the left-hand terminal of push button switch PB1 D. Right-hand terminal of push button switch PB1 to the + terminal of motor M1 E. Terminal I of switch SW1 (piggy-back) to terminal A of bulb L1 F. Terminal I of switch SW1 (piggy-back) to terminal C of bulb L2 3. Connect BLACK jumper wires to the following locations : A. Terminal B of bulb L1 to any of the four BLACK ground receptacles B. Terminal D of bulb L2 to any of the four BLACK ground receptacles C. Terminal – of motor M1 to any of the BLACK ground receptacles 4. Draw the circuit you have just constructed on a blank trainer schematic sheet and label the schematic : SA-12 PAR- ALLEL CIRCUITS BEHAVIOR. SA-12 — Circuit Explanation Light bulbs L1 and L2 as well as the motor M1 are all connected in parallel. Each one is powered by the positive circuit through fuse F1. However, switch SW1 controls lights L1 and L2, but not motor M1. Motor M1 is controlled by push but- ton switch PB1. However, in order for motor M1 to operate, switch SW1 must be in the on position. This is a good exam- ple of common parallel circuits used in vehicles. Many devices may be protected by a single fuse, but can be switched in many different ways. So, in this circuit, bulb L1, L2 and motor M1 and all connected in parallel even though they use individual ground circuits. If fuse F1 were to blow open, all three devices would no longer work. However, if there was a problem in just one of the three ground circuits, then only that device would malfunction, but the other two devices would operate normally. It is important that you fully understand this circuit before proceeding. 5. Turn SW1 ON and confirm that bulb L1 and L2 operate at full brilliance. 6. With SW1 still ON, push down the PB1 switch button and confirm that motor M1 starts rotating. 7. If any of the three parallel branches didn’t operate properly, go over your wiring and correct the problem. 37 95-CL-1919-06 Module 3 — SA-12 consulab.com info@consulab.com 8. Carefully measure the total circuit current and record your measurement on the answer sheet. Turn switch SW1 OFF. 9. Measure the resistance of resistor R1 and record your measurement on the answer sheet. 10. Study the circuit and make a prediction about circuit behavior IF resistor R1 were to be installed in the positive feed circuit. Put your prediction on the answer sheet. 11. Remove the RED wire from terminal O of switch SW1 and connect it to terminal J of resistor R1. 12. Install a RED wire from terminal K of resistor R1 and to terminal O of switch SW1. NOTE- You have installed resistor R1 in series with the positive feed circuit to bulbs L1, L2 and motor M1. 13. Turn switch SW1 ON and push switch PB1 down, then describe circuit performance on the answer sheet. 14. Measure the total circuit current and record your measurement on the answer sheet. 15. Based on your current measurements in steps 7 and 13, describe why the circuit is behaving the way it is on the answer sheet. 16. Turn switch SW1 OFF. 17. Measure the resistance of resistor R2 and record your measurement on the answer sheet. 18. Move RED wire from terminal J of resistor R1 to terminal L of resistor R2. 19. Move RED wire from terminal K of resistor R1 to terminal M of resistor R2. 20. Predict what the circuit behavior will be with resistor R2 connected in series with the positive feed circuit. Put your prediction on the answer sheet. 21. Turn switch SW1 ON and describe the circuit behavior on the answer sheet. 22. Measure total circuit current and put your measurement on the answer sheet. 23. Turn switch SW1 OFF. 24. Measure the resistance of resistor R4 and record your measurement on the answer sheet. 25. Predict circuit behavior will be with resistor R4 connected in series with the positive feed circuit. Put your prediction on the answer sheet. 26. Turn switch SW1 ON and describe circuit behavior on the answer sheet. 27. Measure total circuit current and record your measurement on the answer sheet. 28. Turn switch SW1 OFF. 29. Measure the resistance of resistor R5 and record your measurement on the answer sheet. 30. Predict what the circuit behavior will be with resistor R5 connected in series with the positive feed circuit. Put your prediction on the answer sheet. 31. Turn switch SW1 ON and describe circuit behavior on the answer sheet. 32. Measure total circuit current and record your measurement on the answer sheet. 33. Turn switch SW1 OFF 34. Write total circuit currents for each resistor in the blanks provided on the answer sheet. 35. What conclusions can you make regarding the amount of resistance in this circuit. Put your answer on the answer sheet. 36. Remove all resistors from the positive side of the circuit and restore the positive side to original circuit construction as in Step 2. Confirm normal circuit operation. Turn switch SW1 OFF. 38 95-CL-1919-06 Module 3 — SA-12 consulab.com info@consulab.com 37. Insert resistor R1 into the ground circuit of bulb L2 by removing the end of BLACK wire connected to the ground receptacles and connecting it to terminal J of resistor R1. Connect another BLACK wire from terminal K of resistor R1 to the ground receptacles. Predict what will happen when switch SW1 is turned ON. Put your prediction in the answer sheet. 38. Turn switch SW1 ON and describe circuit behavior on the answer sheet. 39. Measure the current flow in bulb L2 circuit. Put your measurement on answer sheet. 40. Temporarily bypass resistor R1 by connecting a BLACK jumper wire from terminal J to terminal K of resistor R1. 41. Measure the current flow in bulb L2 circuit with resistor R1 bypassed. Remove bypass BLACK jumper wire. Record your measurement on answer sheet. NOTE : This assignment demonstrates that in parallel circuits, unwanted resistances can be in a location that affects all parts of the circuit OR can be located in just one branch of the parallel circuit which will affect only that branch. 42. Measure the voltage drop across bulb L2. 43. Measure the voltage drop of bulb L2 ground circuit. NOTE : This assignment demonstrates how to locate unwanted resistances in both series or parallel circuits. The voltage drop test of each connection should be close to zero if testing anywhere in either the positive or ground circuits. Total voltage drop across bulb L2 without any resistances should be close to source voltage. It is important that you completely understand how to use voltage drop testing to locate unwanted resistances. 44. Repeat steps 36 through 40 with resistor R5 and record your current measurements on answer sheet. It is not neces- sary to record your predictions, but should be discussed among yourselves. 45. Turn switch SW1 OFF, remove all jumper wires from trainer and digital multimeter and turn in your completed an- swer sheet to your instructor. 39 95-CL-1919-06 Module 3 — SA-12 consulab.com info@consulab.com SA-12 — Parallel Circuit Behavior - Student Answer Sheet Name : Group : Date : 8. amps of total parallel circuit current. Expressed as : 9. ohms of resistor R1. Expressed as : 10. Prediction : 13. Circuit Description : 14. amps of circuit total with R1. Expressed as : 15. Prediction : 17. ohms of resistor R2. Expressed as : 20. Prediction : 21. Circuit Description : 22. amps of circuit total with R2. Expressed as : 24. ohms of resistor R4. Expressed as : 25. Prediction : 26. Circuit Description : 27. amps of circuit total with R4 Expressed as : 29. ohms of resistor R5 Expressed as : 40 95-CL-1919-06 Module 3 — SA-12 consulab.com info@consulab.com 30. Prediction : 31. Circuit Description : 32. amps of circuit total with R5 Expressed as : 34. A. amps without any resistor Expressed as : B. amps with resistor R1 Expressed as : C. amps with resistor R2 Expressed as : D. amps with resistor R4 Expressed as : E. amps with resistor R5 Expressed as : 35. Conclusions : 37. Prediction : 38. Circuit Description : 39. amps of bulb L2 ground with resistor R1 Expressed as : 41. amps of bulb L2 ground with resistor bypassed. Expressed as : 44. A. amps of bulb L2 ground with resistor R5. Expressed as : B. amps of bulb L2 ground with resistor R5 bypassed Expressed as : Instructor grade : Comments : 41 95-CL-1919-06 Module 3 — SA-13 consulab.com info@consulab.com SA-13 — Circuit Behavior in Series and Parallel Circuits LAW : In a SERIES CIRCUIT, the total circuit resistance is the sum of each individual resistances. As more resistances are added, the total circuit resistance will also increase and the total circuit current will decrease. LAW : In a PARALLEL CIRCUIT, the total circuit resistance is LESS that the lowest value resistance. As more resistances are added, the total circuit resistance will decrease and the total circuit current will increase SA-13 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-13 student answer sheet to record all of your measurements and question answers. 1. There should be no jumper wires connected to the trainer at this point. 2. Using the DMM, measure the resistances of R1, R2, R3, R4 and R5 and record your readings on the answer sheet for assignment SA-13. 3. In the next steps, you will be working with resistors R3 and R4 which have equal values. Remembering the “laws of circuit behavior” for series and parallel circuits, let’s conduct a few experiments to prove these “laws”. 4. The trainers power switch should be turned OFF and the digital multimeter should be turned ON and adjusted for measuring resistance. 5. Connect a jumper wire from terminal O of resistor R3 to terminal Q of resistor R4. This leaves terminals N & P open. Resistors R3 and R4 are connected in “series”. 6. Connect the leads of the ohmmeter (piggy-back) to terminals N of resistor R3 and terminal P of resistor R4. Record your reading on the answer sheet. CONCLUSIONS : When any two resistors connected in a series circuit, the total circuit resistance is the sum of the two resistors added together. 7. Remove previously used jumper wires and the DMM. 8. Connect a jumper wire from terminal O of resistor R3 to terminal Q of resistor R4. 9. Connect a jumper wire from terminal N of resistor R3 to terminal P of resistor R4. 10. Connect the leads of the ohmmeter to terminals P and Q of resistor R4 or terminals N and O of resistor R3. Record your reading on the answer sheet. CONCLUSIONS : Resistors R3 and R4 are connected in parallel. Because resistors R3 and R4 are identical in value (20 Ω), the total circuit resistance is equal to one-half of either resistor or (10 Ω). If the resistors were not of equal value, the total circuit resistance will still be less than the lowest value resistor. 42 95-CL-1919-06 Module 3 — SA-13 consulab.com info@consulab.com 11. Connect resistors R1, R2, R3, R4 and R5 in the following sequences, then measure the total circuit resistances for each combination and record your measurements on the answer sheet. Be sure to carefully follow each step carefully to avoid errors. 12. R1, R2, and R3 in parallel. Measure total circuit resistance and record on answer sheet. 13. R1, R2 and R3 in series. Measure total circuit resistance and record on answer sheet. 14. R3, R4 and R5 in parallel. Measure total circuit resistance and record on answer sheet. 15. R1, R2, R3, R4 and R5 in series. Measure the total circuit resistance and record on answer sheet. 16. R1, R2, R3 and R4 in parallel. Measure the total circuit resistance and record on answer sheet. 17. R1, R2, R3, R4 and R5 in parallel. Measure the total circuit resistance and record on answer sheet. CONCLUSIONS : Adding resistances in a parallel circuit will decrease the total circuit resistance which in turn will cause an increase of total circuit current flow. Adding more resistances in a series circuit will increase the total circuit resis- tance and thus, will cause a reduction of total circuit current. These relationships are extremely important to learn and remember. 18. Remove all jumper wires from the trainer and turn off the ohmmeter. Hand in your answer sheet to your instructor. After completion of SA-13, turn in your answer sheet to the instructor and ask for Test 9 before proceeding to the next assignment. 43 95-CL-1919-06 Module 3 — SA-13 consulab.com info@consulab.com SA-13 — Circuit Behavior in Series & Parallel Circuits - Student Answer Sheet Name : Group : Date : 2. R1 : ohms. Expressed as : R2 : ohms. Expressed as : R3 : ohms. Expressed as : R4 : ohms. Expressed as : R5 : ohms. Expressed as : 6. ohms of this series circuit. Expressed as : 10. ohms of this parallel circuit. Expressed as : 12. ohms of this parallel circuit. Expressed as : 13. ohms of this series circuit. Expressed as : 14. ohms of this parallel circuit. Expressed as : 15. ohms of this series circuit. Expressed as : 16. ohms of this parallel circuit. Expressed as : 17. ohms of this series circuit. Expressed as : Instructor grade : Comments : 44 95-CL-1919-06 Module 3 — SA-14 consulab.com info@consulab.com SA-14 — Combination Series / Parallel Circuits SA-14 — Combination Series / Parallel Circuits Explanation A combination series/parallel circuit is a circuit that is connected with both series and parallel connected resistances. There are branches of the circuit with resistances connected in series, while other branches have resistances connected in parallel. It is not possible to apply a fixed set up rules for circuit behavior in combination series/parallel circuits. The circuit must be “organized” into portions and each analyzed separately. In the automobile, many parallel circuits are used, but certain branches of the parallel circuit can become a combination series/parallel circuit if unwanted resis- tance becomes present in the circuit. The following assignments will demonstrate this concept. Be sure to carefully read each step to avoid confusion. 14.00-14.60 V F1 SW1 L1 L2 R2 BLK GND SA-14 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-14 student answer sheet to record all of your measurements and question answers. 1. Make sure the CL-1919-06 trainer is properly set up and is plugged in to a 120V receptacle. 2. Turn the CL-1919-06 master power switch ON. The voltage display should be on. Adjust the voltage adjustment knob until the voltage displayed is 14.00-14.60 volts. 3. Connect RED jumper wires to the following locations : A. Any of the four RED + power terminals of the trainer to left-hand yellow terminal of the F1 fuse. B. The right-hand yellow terminal of fuse F1 to terminal O of switch SW1. C. Terminal I of switch SW1 to terminal A of bulb L1. D. Terminal I of switch SW1 (piggy-back) to terminal C of bulb L2. 4. Connect BLACK jumper wires to the following locations : A. a. Terminal B of bulb L1 to any of the BLACK ground terminals on the trainer. B. b. Terminal B of bulb L1 (piggy-back) to terminal D of bulb L2 (NOTE-This is a “shared” or common ground path for both bulbs and is a very common method of circuit construction in automobiles.). 5. Turn switch SW1 to the on position. Both L1 and L2 bulbs should now be on a full brilliance. This circuit is a parallel circuit with the two bulbs sharing a common ground circuit and a common power circuit. Confirm proper circuit operation. 45 95-CL-1919-06 Module 3 — SA-14 consulab.com info@consulab.com 6. Turn switch SW1 off. 7. Disconnect the RED jumper wire from terminal C of bulb L2. 8. Connect the disconnected end from step #7 to terminal M of resistor R2. 9. Connect a RED jumper wire from terminal L of resistor R2 to terminal C of bulb L2. This step inserts resistor R2 in series with bulb L2. Bulb L1 still is connected to switch SW1 without any resistance. 10. Draw the circuit you have just constructed on a blank trainer schematic sheet and label the schematic : SA-14 COM- BINATION SERIES/PARALLEL CIRCUIT. 11. Predict what the circuit performance will be and record your answer on the answer sheet. 12. Turn switch SW1 to the on position and observe the performance of bulbs L1 and L2. Were you correct in your prediction ? Put your answer on the answer sheet. EXPLANATION : The circuit with the resistor inserted is a combination series/parallel circuit. Bulb L1 shares full source voltage with only the resistance of the bulb L1 and illuminates at full brightness. Bulb L2 has the resistance of R2 in se- ries with it and thus current flowing through R2 reduces the current available to L2 because there is only one path in that branch for current to flow. This is the series portion of the circuit. Bulbs L1 and L2 are in parallel with each other but L2 has an additional resistance of R2 in that branch. 13. Measure the available voltage at L1 and L2 and record your measurements on the answer sheet. 14. Measure the voltage drop across resistor R2 and record on the answer sheet. 15. Add the available voltage at L2 with the voltage drop of resistor R2 and record the answer on the answer sheet. CONCLUSIONS : With resistor R2 inserted in the L2 bulb branch and becoming a series circuit in that branch, there is only one path for current to flow. Therefore, resistor R2 reduced the source voltage to L2 by 7.07 volts and thus bulb L2 only has about 7.0 volts to operate. This results in bulb L2 operating much dimmer than it is designed to. This circuit is a good example of common problems in automotive circuits where unwantedresistance is present in one of the parallel branches. In this case, the problem could not be in the ground circuit because both bulbs share the same ground. NOTE- The only exception to this would be a corroded or loose electrical ground connection at bulb L2 which would insert additional resistance for that branch of the circuit. 46 95-CL-1919-06 Module 3 — SA-14 consulab.com info@consulab.com SA-14 — Combination Series / Parallel Circuits - Student Answer Sheet Name : Group : Date : 11. 12. Yes or No. 13. A L1 available volts. Expressed as : B L2 available volts. Expressed as : 14. voltage drop across R2. Expressed as : 15. L2 available + R2 voltage drop = volts. Instructor grade : Comments : 47 95-CL-1919-06 Module 3 — SA-15 consulab.com info@consulab.com SA-15 — Series/Parallel Circuit w/Resistance in One Ground Path Branch SA-15 — Explanation In this assignment, you will first construct a parallel lighting circuit consisting of bulbs L1 and L2, and bulb LED L3. After confirmation of correct operation, you will insert a resistance into the ground circuit of LED L3 making that branch a series circuit. Be sure to carefully read the instructions to avoid errors. SA-15 — Procedure Be sure to carefully follow all instructions and always ask your instructor if you have any questions. Use the SA-15 student answer sheet to record all of your measurements and question answers. 1. Make sure the CL-1919-06 trainer is properly set up and is plugged in to a 120V receptacle. 2. Turn the CL-1919-06 master power switch ON. The voltage display should be on. Adjust the voltage adjustment knob until the voltage displayed is 14.00-14.60 volts. 3. Connect RED jumper wires to the following locations : A. Any of the four RED + power terminals of the trainer to left-hand yellow terminal of the F1 fuse. B. The right-hand yellow terminal of fuse F1 to terminal O of switch SW1. C. Terminal I of switch SW1 to terminal A of bulb L1. D. Terminal A of bulb L1 (piggy-back) to terminal C of bulb L2. E. Terminal C of bulb L2 (piggy-back) to terminal LO of bulb LED L3. 4. Connect BLACK jumper wires to the following locations : A. Terminal B of bulb L1 to any of the BLACK ground terminals on the trainer. B. Terminal B of bulb L1 (piggy-back) to terminal D of bulb L2 (NOTE - This is a “shared” or common ground path for both bulbs and is a very common method of circuit construction in automobiles.). C. Terminal COM of LED L3 to any of the four BLACK ground receptacles on the trainer NOTE- This is a dedicated ground circuit for bulb LED L3. 5. Draw the circuit you have just constructed on a blank trainer schematic sheet and label the schematic : SA-15 SERIES/PARALLEL CIRCUIT w/RESISTANCE IN ONE GROUND PATH BRANCH. 6. Turn switch SW1 to the on position and confirm proper circuit operation. All three bulbs should be ON at full bril- liance. 7. Using the DMM setup to measure voltage, measure the available voltage to each bulb and record on the answer sheet. 48 95-CL-1919-06 Module 3 — SA-15 consulab.com info@consulab.com 8. Make the following modifications to the circuit. Identify the BLACK jumper wire connected from LED L3 COM to any of the four BLACK ground receptacles. Remove the end of that BLACK jumper wire connected to any of the four ground terminals and connect it to terminal N of resistor R3 (do not disconnect the end of that BLACK jumper wire connected to LED L3 COM). 9. Connect a BLACK jumper wire from terminal O of resistor R3 to any of the four BLACK ground receptacles of the trainer. A resistance (R3) has been inserted into the ground circuit of bulb LED L3 LO which makes that branch a series circuit. Current must flow through the resistor before it can get to ground. 10. Predict what the circuit performance will be when you turn the switch on. Record your answer on the answer sheet. 11. Turn on switch SW1 and observe circuit performance. 12. Using the DMM set up for voltage, measure available voltage at L1, L2 and LED L3 LO and record your readings on the answer sheet. NOTE : Be sure to have the negative lead of your voltmeter at the ground terminal of each bulb you are checking. Failure to do so will result in wrong readings. In order to check “available voltage”, the voltmeter leads MUST be attached at the device’s positive and ground circuit connections. 13. Conduct a voltage drop test across resistor R3 and record your reading on the answer sheet. EXPLANATION : The inserted resistance of R3 in the ground circuit of bulb LED L3 LO causes a voltage drop on the ground side. Resistance in either the positive or ground side of a circuit will cause a reduction in available voltage to the device. The technician’s job is to locate the source of the unwanted resistance and make the necessary repairs. Without the inserted resistor, this circuit was a parallel circuit with three branches. After the resistor was inserted, it became a combination series/parallel circuit with the branch of bulb LED L3 LO becoming a series circuit. However, if the techni- cian placed the BLACK lead of the voltmeter to a “common” ground connection, the voltmeter would read full source voltage and the resistance in the ground circuit would not have been discovered. CONCLUSIONS : This exercise reinforces the fact that unwanted resistances can be either in the positive side or the neg- ative side of a circuit or even both sides at the same time. Unwanted resistances reduce the available voltage delivered to the device and often results in improper performance of the device. Examples are : 1. Dim bulbs. 2. Slow motor operation. 3. No operation of device at all. It is important to remember that when checking “source voltage”, the voltmeter leads should be attached to the battery or source of the supply voltage. When checking “available voltage”, the voltmeter leads should be attached to the pos- itive and ground terminals of the device being checked. This is a VERY IMPORTANT diagnostic fact to remember when checking circuit performance. After completion of SA-15, turn in your answer sheet to the instructor and ask for Test 10 before proceeding to the next module. 49 95-CL-1919-06 Module 3 — SA-15 consulab.com info@consulab.com SA-15 — Series/Parallel Circuit w/Resistance in One Ground Path Branch - Student Answer Sheet Name : Group : Date : 7. A. volts L1. Expressed as : B. volts L2. Expressed as : C. volts LED L3 LO. Expressed as : 10. 12. A volts L1. Expressed as : B. volts L2. Expressed as : C. volts LED L3 LO. Expressed as : 13. R3 voltage drop. Expressed as : Instructor grade : Comments : 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada © ConsuLab Educatech Inc, 2024. All rights reserved. Trainer Layout and Familiarization Front Panel Component Identification Electrical Component Identification Electrical Accessories Trainer Use and Operation Warnings and Cautions Student Learning Modules MODULE 3 Ohm’s Law Definition and Relationships SA-4 — Series Circuits SA-4 — Series Circuit - Student Answer Sheet SA-5 — Series Circuits with One Resistance SA-5 — Series Circuit with One Resistance - Student Answer Sheet SA-6 — Series Circuits with Two Resistances SA-6 — Series Circuits with Two Resistances - Student Answer Sheet SA-7 — Series Circuits with Two or More Resistances SA-7 — Series Circuits with Two or More Resistances - Student Answer Sheet SA-8 — Available Voltage Test SA-8 — Available Voltage Test - Student Answer Sheet SA-9 — Positive Voltage Drop Testing SA-9 — Positive Voltage Drop Testing - Student Answer Sheet SA-10 — Ground Side Voltage Drop Testing SA-10 — Ground Side Voltage Drop Testing - Student Answer Sheet SA-11 — Parallel Circuits with Two or More Resistances SA-11 — Parallel Circuits with Two or More Resistances - Student Answer Sheet SA-12 — Parallel Circuits Behavior SA-12 — Parallel Circuit Behavior - Student Answer Sheet SA-13 — Circuit Behavior in Series and Parallel Circuits SA-13 — Circuit Behavior in Series & Parallel Circuits - Student Answer Sheet SA-14 — Combination Series / Parallel Circuits SA-14 — Combination Series / Parallel Circuits - Student Answer Sheet SA-15 — Series/Parallel Circuit w/Resistance in One Ground Path Branch SA-15 — Series/Parallel Circuit w/Resistance in One Ground Path Branch - Student Answer Sheet
