Not Permitted in Class

Not Permitted in Class MSCI 222C Spring 2019 Introduction to Electronics Charles Rubenstein, Ph. D. Professor of Engineering & Information Science Session 5: Mon/Tues 02/25/19 & 02/19/19 Mondays 1:00-3:50pm; Tuesdays 2:00-4:50pm ARC E-13 1 Be sure to have all cellphones OFF 2 222-01 Class Seating Chart - Spring 2019 Cabinet Cabinet FRONT Whiteboard Instructor Station 18 17 16 Kirill Dillon Morgan 21 20 19 Terry Annie Barkin 222-02 Class Seating Chart Tuesdays Cabinet Demo DESK FRONT Whiteboard Instructor Station 3 2 1 Yingshi Jada Nicholas 6 5 4 Jiaqi Bei Elizabeth MONDAY 1pm 24 23 22 Adam Allyson William 27 26 25 Rue Michelle Connie TUESDAY 2pm 9 8 7 Atlas Mila 12 11 10 Jenna Anurag Matt 30 29 28 Sylvia Shelby Jasmine 15 14 13 1/29/18 1/24/18 3 4 MSCI 222 Spring 2019 - Class Schedule & Due Dates MONDAY TUESDAY NOTES 28 January 22 January Session 1. Introduction, Review of Syllabus, Basic Concepts 4 February 29 January Session 2. Basic Electronic Devices (Homework #1 Due, Lab 1) 11 February 5 February Session 3. Semiconductor Materials & Diodes (H2, Q1, L2) 18 February 12 February Session 4. Decimal, Binary & Hex Number Systems (H3, Q2, L3) 25 February 19 February Session 5. Analog and Digital Concepts (H4, Q3, L4) 4 March (*) 26 February Session 6. The Operational Amplifier (H5, Q4, L5) 18 March 5 March (*) Session 7. Digital Integrated Circuit Logic Gates (H6, Q5, L6) 11 March 12 March Spring Break 11-15 March 2019 19 March No Tuesday Class 25 March (**) 26 March (**) Session 8. Flip-Flops & "Clocks"; (H6, Q5, L7) 1 April (***) 2 April (***) Session 9. Digital Counters (H7, Q6, L8) 8 April 9 April Session 10. Digital Shift Registers (H8, Q7, L9) 15 April 16 April Session 11. Using Analog & Digital IC Circuits Together (H9, Q8, L10) 22 April 23 April Session 12. Interfacing Computers (H10, Q9) 29 April 30 April Session 13. RFID (Q10) Last Day for Lab Submissions NOTE: 6 May Quizzes 7 one Mayweek after homework In-class Final session Examination due & reviewed (Tuesday = Conflict Day) NO Classes: 11-15 March - Midterm Break or on Tuesday 19 March MIDTERM: (*) Distributed; (**) Exam/Draft Paper Due; (***) Reviewed in class In-class Final Exams 6/7 May 2019 5 MSCI 222C Class Readings Schedule In addition to the Class Notes (222Notes.pdf)!!! Session Due Notes 2 EW1: Pp 1-27; Armstrong: Chapters 1 3 (Pp 1-16) 3 EW1: Pp 28-65; Armstrong: Chapters 4 6 (Pp 17-63) 4 EW1: Pp 66-76; Armstrong: Chapters 7 9 (Pp 64-126) 5 EW1: Pp 77 -End; Armstrong: Chapters 10 11 (Pp 127-173) 6 EW2: Pp 1-50 and Pg 90; Armstrong: Chapters 12 13 (Pp 174-230) 7 EW2: Pp 51-79, Review Pg 12; Armstrong: Ch. 14 End (Pp 231-270) 8 EW2: Pp 80 - End, Review Pg 12 (CD4013, CD4017) 9 EW2: Review Pg 12 (CD4013, CD4017) 10 EW2: Review Pg 37 (555 Timer) 11 Review EW1 and EW2 as necessary, Sensors Lab Manual if interested 12 and on Review EW1 and EW2 as necessary EW1 = Basic Electronics: Transistors and Integrated Circuits, Workbook I by Forrest M. Mims, III (ew1.pdf) KEY EW2 = Digital Electronic Projects, Workbook II by Forrest M. Mims, III (ew2.pdf) Armstrong = Man of High Fidelity (armstrong2.pdf) Sensors = Radio Shack Electronic Sensors Lab by Forrest M. Mims, III (sensors.pdf) 6 1

MSCI 222C Hands-on Lab Modules #01: Measuring Resistance and Voltage #02: Voltage Sources, LEDS, Diodes & Characteristic Curves #03: Capacitors, Time Constants & Transistor Gain #04: Voltage Regulation & Transistor Switching #05: Analog IC Voltage Comparator #06: Basic Digital Logic #07: Set-Reset Latches & Type D Flip-Flops #08: Decade Counter and One Shot Switch Debouncer #09: Three Stage Type D Flip-Flop Shift Register #10: NE555 IC Timer Circuits Optional Labs (Additional Labs may be added or substituted): #A: Sound Detector Circuit (Audio-triggered One-shot) #B: Seven Segment Display Decoder-Driver Circuit 7 Instructor Contact Information Dr. Charles Rubenstein <crubenst@pratt.edu> Professor of Engineering & Information Science Pratt Brooklyn Campus Office: ARC G-49 Spring 2019 Office hours (by appointment *) Mondays: 12:00pm - 1:00 pm = ARC G-49 (or E-13) Tuesdays: 12:00pm - 2:00pm = ARC G-49 (or E-13) (*Please email me at least a day in advance if you plan on coming to office hours ) Send me an email crubenst@pratt.edu Subject line: 222C or Electronics 8 * Class Session Archives http://www.charlesrubenstein.com/222/ Spring 2019 - OPEN LAB TIME - ARC E-13 19sp05.pdf (Class PowerPoint slides)* 19sp05_h.pdf (6-slide/page handout format)* *Power points normally available by Thursday evening Mondays 9:00am 1:00pm BY PRE-ARRANGEMENT ONLY CONTACT: Mrs. Margaret Dy-So, Assistant to the Chairperson Math & Science Department ARC G-41 On pre-arranged day, access to E-09 and the White Console Cabinet is obtained from Ms. Dy-So or the student assistant in room G-39 9 10 ** World Maker Faire NY ** For the seventh year, Dr. Rubenstein will be coordinating the IEEE Booth (Sponsored by Region 1, IEEE-USA, EAB and The IET) at the World Maker Faire New York NY Hall of Science - Queens, NY Saturday-Sunday 21-22 September 2019 11 12 2

13 In Today s Class Session 5: DUE: Homework Set #04 Readings: Electronics Workbook 2 (ew2.pdf): Pp. 1-50, 90 Armstrong: Chapters 12-13 (Pp. 174-230) Lecture: Analog and Digital Concepts 2Do: Review Homework Set #04; Quiz #03 (Homework #03) 2Do: Hands-on Module #04: Voltage Regulation & Transistor Switching For class Session 6: DUE: Homework Set #05 Readings: Electronics Workbook 2 (ew2.pdf): Pp. 51-79, 12 Armstrong: Chapters 14-END (Pp. 231-270) Lecture: The Operational Amplifier 2Do: Review Homework Set #05; Quiz #04 on Homework Set #04 2Do: Hands-on Module #05: Analog IC Voltage Comparator 14 MSCI 222C Electronics Review Kirchhoff s Laws - KCL & KVL Ohms Law Power Law emath Calculations Combining Resistors Time Constants Voltage Divider Equation 15 16 Kirchhoff s Laws: KCL KVL KCL: The current going into any point has to be the same as the current going out of the point also called The Law of Conservation of Current KVL: The sum of all the voltages, as you go around a circuit from some fixed point and return there from the opposite direction, and taking polarity into account, is always ZERO also called The Law of Conservation of Voltage OHMS LAW & the POWER LAW There are three common forms for each Equation: Ohms Law: V=IR V = I R R = V / I I = V / R Power Law: P = I V P = I V P = I 2 R P = V 2 / R 17 18 3

About Electronics Math Calculations Ohms Law equation: V=IR and I = V / R 1. If R is 1 Ohm = 1 Ω and V is 1 volt: then I = 1 Ampere 2. If R is 1MΩ = 1,000,000 Ω and V is 1 volt: then I = 1 microampere = (1 ua = 1 µa) 3. If R is 1k Ohm = 1kΩ = 1000Ω and V is 1 volt: then I = 1 milliampere ( = 1 ma) This is the most common calculation for our labs 19 Series Resistors 1. Resistors in SERIES add R ab = R 1 + R 2 + + R n 2. For n Like Resistors in SERIES: R ab = n R 20 Parallel Resistors Simple Series/Parallel Resistor Circuits a 1. The Inverse of Resistances in PARALLEL add 1/R ab = 1/R 1 + 1/R 2 + + 1/R n 2. For n Equal Resistances in Parallel; R ab = R / n 3. For TWO Resistors in Parallel; R ab = R 1 R 2 / (R 1 + R 2 ) R ab b The Equivalent Resistance of the circuit above: R ab = [ R 1 R 2 / (R 1 + R 2 ) ] + R 3 21 22 The Voltage Divider Equation Time Constant NOTES The time required to charge or discharge a capacitor requires calculating: Vout = Vin [ R 2 / (R 1 + R 2 ) ] When a voltage is applied to two (or more) resistors in series, the voltage across a particular resistor is the applied voltage times the selected resistor divided by the sum of the resistors 23 τ = R C With: τ in seconds, R in ohms, and C in Farads 24 4

Measuring Voltage, Calculating Current The technology student must be able to understand the function of various instruments and equipment. In this problem we will compute the voltage drop V 1 (in volts) across the resistance R 1 (measured in ohms) and compare it with the voltmeter reading when the switch is closed. 25 Calculating Voltage Based on Kirchoff s Voltage Law (KVL) and the Voltage Divider Rule, the following information will prove helpful: 1. Kirchoff s Voltage Law V t = V 1 + V 2 2. Voltage Divider Rule V 1 = V t [R 1 /(R 1 +R 2 )] V 1 = 100v [50,000/[50,000+70,000]] V 1 = 100v [50,000/[120,000]] V 1 = 100v [5/12] V 1 = 41.67 volts 26 Calculating Current Based on Kirchoff s Current Law (KCL) and Ohm s Law we see that the current (I, in Amperes) everywhere in a series circuit is the same and thus: 3. Ohm s Law I = V t /R t = 100/120,000 I = 0.00083 Amperes or I = 0.83 milliamperes (0.83 ma) or I = 830 microamperes (830 µa) 27 Diodes in Series Circuits When a resistor (R 1 ) and a diode are connected in series to a voltage source (V) we use KCL to realize the current is the same through all series elements. Using the standard forward voltage drop (V d ) value of 0.6volts and Ohm s Law we find the current through the resistor. For V = 15 and R 1 = 1KΩ : I R = I d = (V - V d )/R 1 = (15-0.6) volts / 1KΩ I R = 14.4 volts / 1K = 14.4 ma 28 MSCI 222C Electronics Week 5 Analog & Digital Concepts Transistors as Switches and Amplifiers How do bipolar junction transistors (BJT) and field effect transistors (FET) work as analog amplifiers and digital switches? 29 30 5

MSCI 222 Electronics Module 5 Semiconductor Construction (PHYSICS Alert!) 31 32 ABOUT WEARABLE TECHNOLOGY In the 1950 s and 60 s with the advent of sensitive transistor and then integrated circuits, perhaps the first wearable technology was developed: The Static Discharge Wrist Band MSCI 222 Electronics Session 5 Transistors as Switches and Amplifiers What do we mean by a signal INVERTER? Zero volts IN = Transistor ON Five volts IN = Transistor OFF A conductive thread woven into a band worn around the technicians wrist to avoid building up static electric charges that could destroy the delicate and sensitive early electronic circuits Demo: Conductive Thread How do bipolar (BJT) and field effect (FET) transistors work as analog amplifiers and digital switches? The next slides illustrate the general principles of electro-lithography used in constructing microscopic transistor and integrated circuit devices 33 34 628 Ohm Diffused Resistor A 2 mil x 6 mil* area of a 200Ω/square semiconductor material either N-type or P-type - forms the628ω resistor seen here in Side view: * 1 mil = 0.001 Semiconductor Resistors and Diodes Connecting from N to N creates a semiconductor resistor. If instead we connect between the P-type substrate and the N-Type layer, a simple PN junction is formed, which (ideally) allows current to flow in ONLY one direction - from Anode to Cathode - We thus create a Diode. Top view 35 36 6

Diodes and NPN Transistors If we add a second N-type junction, as shown below, we have two back-to-back diodes which doesn t seem to be helpful to us... This double junction forms what we call a Transistor. Simply put, if we force enough electrons into the P-material Base to make it look like an N-material, the Collector-Emitter acts a bit like a resistor. With lesser base current, the collector current varies as we will see in the Lab: small I B changes yield LARGE I C changes which provides us with GAIN or h FE Side View: Top Contact NPN Transistor Transistors are REALLY small Shown here is one made from a 20 mil square die (20milx20mil) which is only 4-5 mils thick! 37 ( indicates emitter, collector diffusion areas) If we could make the 200Ω/sq Base material become 0.5Ω-cm then the Collector-Emitter would seem to be a simple resistance NOTE: 1 mil = 0.001 38 Top View: NPN Transistor This (ancient) Transistor uses a 20 mil square die; 4-5 mils thick The contact areas shown are typically aluminum (etc.) Emitter Base Collector A 4-Mask Set fabricates NPN Transistors Base Diffusion Emitter Diffusion* 1 mil Ohmic Contacts *Collector = substrate Contact Metallization Top View Side View 39 40 3-Transistor Monolithic IC Amplifier 30 mil square die with Monolithic IC Amplifier Schematic Three transistors Three diffused resistors 30 mil square die (Gray = Metallization; Black = Ohmic Contacts) 41 42 7

VLSI Computer Chips on a Wafer Apx. 28 x 28 @ 6.5mm chips 500-600 per 8 wafer What the individual cardboard-thick memory circuit chips look like Very Large Scale Integrated Circuits Similar VLSI Integrated Circuit Chip 6mm square die; 30,000 transistors; 144 pin package 144 (!) Connections Needs at least a dozen masks! Mask Registration Notch 43 44 TMS2516: 2Kbyte EPROM TMS2516 UV Light Erasable Programmable Read-only- Memory (EPROM): 16,384 bits as 2,048 Bytes 2.5mm x 4mm die in a 24-pin DIP ceramic package about 20,000 transistors Very Large Scale Integrated Circuits IBM 1 Megabyte RAM Integrated Circuit Chip 5mm x 10mm die; 1 million + transistors 45 46 Motorola MC68000 Microprocessor (1983) A 16-bit Microprocessor Chip: 246mil x 281mil die; 70,000 transistors 74LS02: Quad 2-Input NOR Gate The 74LS02: Quad 2-Input NOR Gate has a 2mm square die in a 14-pin DIP ceramic package. The four NOR Gates contain about 16 components 47 48 8

MSCI 222 Electronics Module 5 Transistor Circuit Design Basics 49 50 About Transistors NPN Transistor Symbol and packaging Transistors can be divided into a Base-Emitter INPUT circuit where the B-E forms a silicon diode (0.6V forward voltage drop) and a Collector-Emitter OUTPUT circuit, where the C-E current: I C, is controlled by I B and h FE : Voltage Dividers in a Transistor Circuit In the lab, we will create a circuit to find the current gain in the collector of the 2N5551 NPN transistor. NOTE: R 1 is a 10Kohm potentiometer that controls the voltage across R 2 and (by KVL) : V R2 = V R1b -V be (~ 0.6volts ) V R1b can be calculated from the voltage divider rule: V R1b = V cc [R 1b / (R 1a +R 1b )] and the current flowing into the base of the silicon transistor (by KCL): I B * h FE = I C 51 I b = I R2 = V R2 / R 2 52 Voltage Dividers in Transistor Circuits Transistor Base Voltage Divider Network R 1 R 2 Collector Current Gain in Transistors The current gain h FE of a transistor can be measured by dividing the current flowing in the device s collector lead (I C ) by the current flowing in the device s base lead (I B ) The formula for current gain is defined as: h FE = I C / I B The general voltage divider equation becomes: V base = V cc [ R 2 / (R 1 + R 2 ) ] where R 1 is the resistor to the positive voltage source (+) and R 2 is the resistor to ground (parallel to the transistor s base). NOTE: the Base-Emitter junction is a forward biased diode! 53 If we have h FE and I B ; I B x h FE = I C 54 9

Transistors as Amplifiers When the current gain h FE of a transistor is not too high, in a well designed circuit, small variations in base input current produces an amplification of the base-emitter signal in the transistor s collector! The formula for current gain is: h FE = I C / I B If the h FE gain of the 2N5551 is apx. 150 170 Then: 150 (I B ) = I C HOWEVER, I C is limited by the maximum current the external circuit can supply Transistors as Switches When the current gain h FE of a transistor is high a very small amount of base current (I B ) can make the current flowing in the device s collector lead (I C ) reach its maximum level. This level is called saturation. At saturation instead of amplifying the base current, the transistor acts like a switch. Hands-on Module #03 s circuit acts like a switch to turn the LED ON and OFF by small changes in the rotation of the 10Kohm pot knob. 55 56 About Transistor Calculations We saw earlier that we deal with the Base-Emitter and Collector-Emitter circuits separately as if they were unrelated - while at the same time note that I B * h FE = I C We also saw that the NPN schematic symbol can be divided into both a Base-Emitter INPUT circuit and a Collector-Emitter OUTPUT circuit. B-E forms a silicon diode and the C-E current, I C, as noted above, is controlled by I B and h FE 57 58 Homework #03 Quiz Resistors in Series & Parallel MSCI 222C Electronics Homework #04 Transistor Circuits Review 59 60 10

Homework 4.A Armstrong Questions Armstrong Reading Questions: 4.A1a) From your Armstrong readings recall the passage: "Sarnoff was furious. He issued an edict that anyone who allowed Armstrong to (???) again would promptly be fired." What did Armstrong do? Pp. 123-124: He went out on the roof and to the top of the antenna tower to pose for a picture 4.A2) The signature by the Notary on Armstrong's crucial document appeared to be forged. What was the explanation? Pg. 130: The notary had two official signatures Homework 4.B1 4.B1 What would the collector current I C have to be if the base current I B is 0.02 ma? We are given h FE = 200 Recalling that I C = h FE x I B Thus I C = (200) (0.02 ma) I C = 4.0 ma =============================================== BTW: If I B = 0.02 ma, and R 2 = 100Kohms, V R2 = I B x R 2 = 0.02 ma 100K = 0.02E-3 100E+3 and V R2 = 2.0 volts 61 62 Homework 4.B2 4.B2 What would the collector current I C have to be if the voltage from the potentiometer slider to ground is approximately 5.0 volts? Using KVL: V R1-G -V R2 -V BE = 0 V R1-G From which: V R2 = V R1-G -V BE Since V R1-G = 5.0 v and V BE = 0.6 v, V R2 = V R1-G - V BE = 5.0 0.6 = 4.4 Volts Using KCL: I R2 = I B = I E I R2 = V R2 / R 2 = 4.4 Volts / 100Kohms = 4.4 E-5 A or 0.044 ma I C = h FE x I B = (200) (0.044 ma) I C = 8.8 ma 63 Homework 4.B3 4.B3 If the base current is 0.2mA and h FE = 200 explain why the collector current I C will be much less than 40 ma. The collector current must be less than 16 ma because: a. The h FE equation calculates I C (saturated) I C = h FE I B I C = (200) (0.2 ma) I C = 40 ma ; b. BUT with a 1Kohm resistor in the collector circuit, Ohms Law states that the voltage drop across a resistor if the current flowing through it is 40 ma is: V CC = I R ; V = 40 ma 1K ohm = 40 Volts! c. However, we only have a 16 Volt input voltage: V CC = 16 v therefore the MAXIMUM current that can flow in the 1K Ω collector resistor R 3 is limited to 16V/1K = 16 ma! = less than 40mA! 64 65 In The Next Class Session 6: DUE: Homework Set #05 Readings: Electronics Workbook 2 (ew2.pdf): Pp. 51-79, 12 Armstrong: Chapters 14-END (Pp. 231-270) Lecture: The Operational Amplifier (Op Amps) 2Do: Review Homework Set #05; Quiz #04 (Homework #04) 2Do: Hands-on Module #05: Analog IC Voltage Comparator *** Midterm Distributed March 4 & 5! *** For class Session 7: DUE: Homework Set #06 Readings: Electronics Workbook 2 (ew2.pdf): Pp. 80-END, 12 Lecture: Digital Integrated Circuit Logic Gates 2Do: Review Homework Set #06; Quiz #05 on Homework Set #05, 2Do: Hands-on Module #06: Basic Digital Logic 66 11

MSCI 222 Electronics Hands-On Lab Module 4: Voltage Regulation & Transistor Switching ** CAUTION ** Most electronic component leads have been tinned with a tin-lead coating to make them easier to solder into a circuit. Although we will NOT do soldering in this class, AFTER working with components, please avoid lead poisoning by washing your hands. Thank You! 67 68 Basic Lab Notes 1) All measurements should be made with the Digital Multimeter in your Pratt Kit (Type KT-820B.or DT-830D). To conserve your multimeter s 9V battery, be sure to turn the meter off if not in use for over 5 minutes. 2) All work is to be done individually, and submitted before you leave the class. Double check when leaving that your meter is turned off and in your Pratt kit. There are no lab reports" in this course. 3) Enter all results on both the Instructions Sheet, and the Results Sheet. Keep the Instruction Sheets as a reference. Turn in the Results Sheets at the end of the period, finished or not, for grading. 69 Parts Needed for Lab Module 4 KEEP the following Lab 3 Parts (1) GREEN Light-Emitting Diode (LED) (1) 1KΩ Resistor (R3) (1) 10KΩ Potentiometer Pot (R1) (1) 2N5551 Transistor (Q1) NEW for Lab 4: (1) 10KΩ Resistor (R2) changed from 100KΩ in Lab 3 (1) 7805 IC Voltage Regulator (1) 1N4007 Rectifier Diode (1) 1µF Electrolytic Capacitor NOTE: Normally a 10µF Electrolytic Capacitor is used between the LM7805 input and ground. As our Adapter has a 1,000 µf Electrolytic Filter Capacitor, it is NOT needed. (Radio Shack Electronic Learning Lab Console, 9V AC Adapter, Digital Multimeter, Wire Stripper, Miscellaneous Connecting leads and wires required for all labs) 70 Lab 4-1: 7805 Voltage Regulator Wiring the MC7805 Voltage Regulator as a 5 Volt Source 5V Regulated Power Circuit Part 1 9V adapter Unregulated Power Bus RED wire to Connect A3 to Vcc: 5V Regulated Power V2 then to C2 (Pins A1 B1 C1 Breadboard) Add a GREEN LED to verify power is ON! Keep this circuit wired for the whole semester! 71 Insert 7805 with Metal at LEFT Then the 1uF (+: to A3, -: I3) Then Green LED in series with 1K resistor between +Vcc and Ground [Optional: 10uF (+: C2 and : I1)] Connect I4 to GND 4; B5 to I5, 9V adapter Black is GND 72 12

Adding Capacitors, LED display to 5v Regulator Unregulated +9v from Adapter 7805 Voltage Regulator IC Metal TAB at LEFT Optional C1 = 10 µf Don t use +9V UNreg. 1kΩ Regulated +5volts 1 µf GROUND Green LED Lab 4: Voltage Regulation, Relay Resistance Measuring Unregulated and Regulated Power Supply Voltages 4.1a) Turn the Console Power ON The unregulated, unloaded supply voltage is (expect 9 17 volts DC) V. 4.1b) The regulated supply voltage is (expect 4.5 to 5.5 volts) V. 4.2a) Turn the Console Power OFF. Use your Multimeter to measure the coil resistance of the relay on the Console between Spring #57 and Spring #58. The Relay Coil resistance is ohms This is Instructor check point 4A 73 74 Lab 4-3: Transistor Switching: Relay & Buzzer Circuit Wire this transistor switching circuit, using R1 and the transistor from last week s lab to test the relay operation. NOTE: Replace 100K! R2 is now 10KΩ Possible Switching Circuit Layout Transistor Switch Circuit D1 = 1N4007 R2 = 10k Add diode, connect Relay & Buzzer using springs Relay Transistor 2N5551 75 76 Possible Complete Circuit Layout 7805 Voltage Regulator Transistor Switch Buzzer 10K Pot Relay Lab 4-3: Pull In Voltages Measuring Relay Pull In Voltages 4.3a) Measuring the voltage between Spring #57 and Spring #58, adjust the 10Kohm pot to find the lowest relay coil voltage V relayon which causes the relay to close sounding the buzzer. V relayon = volts to close the relay & operate buzzer 4.3b) Now measure the 10Kohm pot voltage V poton from Spring #38 to Spring #39 which creates this voltage. V poton = volts to close relay and operate buzzer 77 78 13

Lab 4-3: Drop Out Voltages Measuring Relay Drop Out Voltages 4.4a) Find V relayoff (the voltage at which the relay opens and buzzer goes off) V relayoff = volts to open the relay (equals relay dropout voltage) 4.4b) Find V potoff (the voltage at the pot corresponding to this turn off voltage) V potoff = volts gives the above result (equals pot dropout voltage) This is instructor check point 4B 79 Lab 4: Completed Transistor Switching Circuit +5 Volt Voltage Regulator Circuit DO NOT REMOVE! \ Switching Transistor Test Circuit 80 Any Send me an email crubenst@pratt.edu or c.rubenstein@ieee.org 81 82 End 83 14