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1 Old Colony Council Merit Badge University March 2012 Joe Mulcahey Len Barrett Sean Mulcahey Based on the Electronics Merit Badge classes taught at the.

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Presentation on theme: "1 Old Colony Council Merit Badge University March 2012 Joe Mulcahey Len Barrett Sean Mulcahey Based on the Electronics Merit Badge classes taught at the."— Presentation transcript:

1 1 Old Colony Council Merit Badge University March 2012 Joe Mulcahey Len Barrett Sean Mulcahey Based on the Electronics Merit Badge classes taught at the 2005 & 2010 National Jamborees Rev. S, 01MAR12 Electronics Merit Badge

2 2 Class 1Safety (Requirement 1) March 3Electricity & Electronics Introduction Circuit Diagrams & Schematics (2) Solving Circuit Problems using Ohms Law (5a) Class 2 Job Opportunities in Electronics (6) March 10Test Equipment Demos (5b) Class 3Proper Soldering Techniques (3) March 24Kit Assembly (4) Electronics Merit Badge Class Outline

3 Safety with Electricity and Electronics 3

4 Electricity Safety High Voltage ( 120V AC or greater) – Safety mainly about not touching the wrong thing Current kills – Only 16 volts can kill when enough electrons flow through the heart or head Ventricular fibrillation – Electrons passing through the heart causes muscles to seize, leading to death If the shock doesnt kill you, you can still be badly burned from touching the wrong thing 4

5 How to Avoid Shock Turn power off before working on equipment Dont touch circuits that could have high voltage on them Do not allow electrons to flow through the heart. I dont think the snake knew about this detail 5

6 Electronics Safety Electronics generally uses lower voltages (less than 48 volts) You are usually working with DC voltage instead of AC voltage You are usually more concerned with sparks from connecting the wrong wires together, or burning yourself with a soldering iron, or some similar event Even when working with lower voltages, you may still receive an electrical shock from equipment you are using 6

7 Personal Safety Be aware of what you are doing, and where you are placing equipment and yourself Pay attention to hot soldering irons Keep a good distance between you and those next to you Know when you are working with high current and/or high voltage circuits THINK before you do something Wear safety glasses when soldering 7

8 One Hand Rule 8 Prevents current from flowing in one arm, through your heart, and out the other arm Keep one hand in your pocket!

9 9 Introduction to Electronics Electrical and Electronics Engineering are both career fields that are involved with Electronics Technology Electrical engineers specializing in power work with motors and generators, and design transmission lines and power plants EEs specializing in electronics deal with communications, such as radio, television and telephony, radar and digital & analog circuit technologies All engineers draw from the fundamentals of science and mathematics They design and work with electrical, electronic, electro-optical, and electromechanical devices, circuits, and systems

10 10 Introduction (Continued) Electrical Engineers collaborate with other professionals in developing sophisticated software tools that support design, verification, and testing Electrical engineering is a discipline that integrates many other disciplines, such as physics, chemistry, mathematics, computer software and hardware, solid-state electronics, communications, electromagnetics and optics, signals and signal processing, systems science, reliability, engineering economics, and manufacturing In order to Learn about Electronics, we must first start by gaining an understanding of what electricity is, both AC (Alternating Current) and DC (Direct Current)

11 Types of Electricity Static Electricity Static electricity is usually created when materials are pulled apart or rubbed together, causing positive (+) charges to collect on one material and negative () charges on the other surface. Sparks may result! Examples of static electricity: 1.Lightning 2.Combing hair 3.Walking across carpet and getting shocked 4.Pulling out scotch tape 11

12 Types of Electricity Alternating Current (AC) The common form of electricity from power plant to home/office. Its direction is reversed 60 times per second in the U.S.; 50 times in Europe. Examples of AC usage: 1.Kitchens: Stoves, ovens, mixer, etc. 2.Computers (the plug) 3.Lights in house 4.Home air conditioners 12

13 Types of Electricity Direct Current (DC) Type of electricity used in most electronics we have today. Current only flows in one direction (not both directions, like AC). Examples of DC usage: 1.MP3 players 2.Radios 3.Electricity in cars 4.Anywhere you use a battery for power 13

14 Basics of Electronics Current: Defined as flow of electrons Current: Units of current is the AMP Current: Electrical symbol for current is I 14

15 Current Flow – Water Analogy 1.Water flows in the hose, entering at the top and exiting the bottom 2.The water is the current; the flow of electrons 3.The more water flowing in the pipe, the more electrons are flowing in the wire 4.Different pipe diameters illustrates different resistance to water flow, which correlates to different resistor values 15

16 Current Current: Defined as flow of electrons Current: Units of current is the AMP Current: Electrical symbol for current is I Common units for current are: –amps –milliamps (mA): 1 mA = amp –microamps ( A) : 1 A = amp, or mA –nanoamps (nA) : 1 nA = amp, mA, or A 16

17 Voltage – Water Analogy 1.Gravity provides the force for water (current) to flow 2.This illustrates a small voltage, so electron flow is small 1.Gravity provides the force for water (current) to flow 2.This illustrates a larger voltage, so electron flow is larger Small height = low voltage Big height = high voltage height 17

18 Voltage Volts is the electrical force that causes electrons (current) to flow Units of volts is the VOLT The symbol of volts is E or V. We will use V Common units for voltage are: –volts –Millivolt (mv) : volt –Microvolt ( v) : volt, or mV –Nanovolt (nv) : volt, mV, or V 18

19 Resistance – Water Analogy Different pipe diameters represents different resistor values The smaller the diameter of the pipe, the larger the resistance 1Ω1Ω 10Ω 100Ω 1000Ω 10000Ω 19

20 Resistance Resistance is an electrical property of a material that resists the flow of electrons The schematic symbol for a resistor is: Common units for resistance are: –ohms –kiloohm: 1KΩ = 1000 ohms, 10KΩ = 10,000 ohms –megaohm: 1MΩ = 1,000,000 ohms The units symbol for ohms is: Ω (ohms) 20

21 Power – Water Analogy In electronics, power is equal to current X voltage The units for power is the WATT The symbol for power is W or P In our water analogy, power is equal to water flow X pressure You can see from the picture that more water flow will mean more force, and more pressure will mean more force

22 Ohms Law One of the most important laws in electronics/electricity V = I x R : Voltage = Current x Resistance Voltage is measure in volts, current is measured in amps, and resistance is measured in ohms 1 amp, going through 1 ohm of resistance, results in a voltage drop of 1 volt 1 V = 1 A x 1 Ω 22

23 More Ohms Law Volts = 10 Resistance = 1000Ω Compute current: I = V / R I = 10 / 1000 =.01A.01A = 10mA Question: what would the current be if the voltage was 1 V? How about 1000 V? Different forms of Ohms Law: V = I x R : Voltage = Current X Resistance I = V / R : Current = Voltage / Resistance R = V / I : Resistance = Voltage / Current 10V 1000 Ω 23 +

24 24 Ohms Law Pie Chart If you know any two values, you can get the other two with these formulas

25 25 Bonus Ohms Law Question: Resistor Cube What is the resistance between points A and B? R R Resistances in series add: R Total =2R Resistances in parallel divide: R Total =R/2

26 26 Where Did the Names of the Electrical Parameters Come From? Volts: Count Alessandro Volta ( ), Italian Scientist Ohms: Georg Simon Ohm ( ), German Physicist Amps: André-Marie Ampère ( ), French Physicist Watts: James Watt ( ), British Engineer Farads: Michael Faraday ( ), British Physicist Henrys: Joseph Henry ( ), American Physicist Other Units: Coulomb, Gauss, Joule, Tesla and of course Smoot

27 27 Smoot? Whats A Smoot? Smoot: A humorous unit of distance invented in 1958 by a fraternity at the Massachusetts Institute of Technology. The fraternity pledges of Lambda Chi Alpha measured the length of Harvard Bridge using pledge Oliver R. Smoot ('62). According to Smoot himself, the bridge turned out to be smoots long "plus epsilon," but this has been recorded as smoots "plus an ear." The bridge is still marked in smoots. Proposals to change the definition of the unit by remeasuring it with Smoot's son Steve (MIT '89) or daughter Sherry ('99) were rebuffed. One smoot equals 67 inches ( centimeters). Oliver Smoot became an attorney but continued his interest in standards and measurement. He is a past Chairman of the Board of Directors of the American National Standards Institute (ANSI) and past President of the International Organization for Standardization (ISO).

28 Electronic Symbols Single Pole, Double Throw Switch (SPDT) Battery Resistor Light Emitting Diode (LED) Buzzer Fuse Lamp or Capacitor Ground W NC NO 28

29 + SWITCHLAMP GROUND FLASHLIGHT TWO GROUND SYMBOLS IS THE SAME AS CONNECTING WITH A WIRE GROUND = 0 VOLTS 29 CIRCUIT DIAGRAM (SCHEMATIC) BATTERY

30 30 Design three different DC circuits Switch Buzzer Light Power Supply Switch Buzzer Light Power Supply Switch Buzzer Light Power Supply Wired to turn Buzzer On/Off Wired to turn Light On/Off Wired to turn Light On in one direction and Buzzer On in other direction DC Circuit Wiring

31 31 Buzzer Light Switch Power + 12 Fuse Direct Current: Draw 3 different wiring test circuits

32 32 Circuit to Switch Buzzer On / Off - Draw the rest of the wires Buzzer Light Switch Power + 12 Fuse Buzzer On Direct Current

33 33 Circuit to Switch Buzzer On / Off Buzzer Light Switch Power + 12 Fuse Buzzer On Direct Current Answer

34 34 Draw Circuit to Switch Light On / Off Buzzer Light Switch Power + 12 Fuse Light On Direct Current

35 35 Draw Circuit to Switch Light On / Off Buzzer Light Switch Power + 12 Fuse Light On Direct Current Answer

36 36 Draw Circuit to Turn Buzzer on in one Direction and Light in other Direction Buzzer Light Switch Power + 12 Fuse Light On Buzzer On Direct Current

37 37 Draw Circuit to Turn Buzzer on in one Direction and Light in other Direction Buzzer Light Switch Power + 12 Fuse Light On Buzzer On Direct Current Answer

38 38 Potentiometer Variable Resistor Power Supply Outputs Volts Batteries In volts Capacitors In Farads Resistor In Ohms Inductor or Coil In henries Transformer Input voltage 120V AC In DC volts Out + Speaker Current Sound Microphone Sound Current + Step Down Step Up Isolated Electronic Components

39 39 Diode PN junction. Current flows in direction of arrow only LED Light Emitting Diode Transistor Electronic Switch. Emitter, Base & Collector terminals. Small current (B-E) controls a larger one (C-E). Made of N (negative) and P (positive) sections NPN (Never Points iN) Meters Current Meter Voltage Meter Resistance Meter Switch Normally Open (n.o.) Normally Closed (n.c.) n.o. n.c. Slide Switch Can connect the center Pole to one of two Throws (SPDT) PNP (Points iN Proudly) Bonus Question: Which type is the Transistor on the Electronics Merit Badge? Anode (P) Cathode (N) Electronic Components

40 40 A Resistors value is indicated by its color bands and is measured in ohms First Ring is First number / Closest to edge of resistor Second Ring is second number Third Ring is number of zeros Fourth Ring is tolerance 1% or 5% or 10% etc. First Ring Black = 0 Brown = 1 Red = 2 Orange = 3 Yellow = 4 Green = 5 Blue = 6 Violet = 7 Gray = 8 White = 9 Third Ring Multiplier Silver = X.01 Gold = X.1 Black = X 1 Brown = X 10 Red = 2 = X 100 Orange = 3 = X 1,000 Yellow = 4 = X 10,000 Green = 5 = X 100,000 Blue = 6 = X 1,000,000 Violet = 7 = X 10,000,000 Resistor Color Code Values Second Ring Black = 0 Brown = 1 Red = 2 Orange = 3 Yellow = 4 Green = 5 Blue = 6 Violet = 7 Gray = 8 White = 9 Fourth Ring Brown = +/- 1% Red = +/- 2% Gold = +/- 5% Silver = +/- 10% None = +/- 20% Resistor Color Rings A Fifth Ring, if present, could indicate reliability or temperature sensitivity

41 41 Black Brown Red Orange Yellow Green Blue Violet Gray White (Gold Silver None) Big Brown Rabbits Often Yield Great Big Vocal Groans When Gingerly Slapped Big Bears Run Over Your Gladiola Bed Vexing Garden Worms Black Bears Run Over Yellow Grass, But Vultures Glide over Water Better Be Right Or Your Great Big Venture Goes West Bye Bye Rosie Off You Go to Birmingham Via Great Western Black Bart's Rambler Over Yonder Gave Bad Vibes Going West Bright Boys Rave Over Young Girls But Veto Getting Wed Big Boys Race Our Young Girls Behind Victory Garden Walls Big Boys Race Our Young Girls But Violet Generally Wins Black Birds Ruin Our Yellow Grain, Butchering Very Good Wheat Billy Brown Ran Over a Yodeling Goat Because Violet's Granny Was Grumpy Bad Betty Runs Over Your Garden But Violet Gray Won't Billy Brown Revives On Your Gin, But Values Good Whisky Better Be Ready, Or Your Great Big Venture Goes West Black Beetles Running On Your Garden Bring Very Good Weather Bowling Balls Roll Over Your Grandpa But Victim Gets Well Batman Bests Robin On Yonder Gotham Bridge; Very Good, Will Get Superman Next! Badly Burnt Resistors On Your Ground Bus Void General Warrantee Big Bart Rides Over Your Grave Blasting Violent Guns Wildly Bad Borg Raid Our Young Galaxy Before Vaporizing Good Walter G-Rated Resistor Color Code Mnemonics

42 42 First Ring Red = 2 Black = 0 Second Ring Red = 2 Third Ring Red = X 100 = 2200 ohms Brown = X 10 = 020 ohms Example of Color Rings First Ring Brown = ____ Green = ____ Second Ring Green = ____ Red = ____ Third Ring Brown = ____ = ___ ohms Yellow = _____ = ____ ohms Test of Color Rings First Ring is first digit Second Ring is second digit Third Ring is number of zeros Ring Black = 0 Brown = 1 Red = 2 Orange = 3 Yellow = 4 Green = 5 Blue = 6 Violet = 7 Gray = 8 White = 9 Resistor Value Examples

43 43 First Ring Red = 2 Black = 0 Second Ring Red = 2 Third Ring Red = X 100 = 2200 ohms Brown = X 10 = 020 ohms Example of Color Rings First Ring Brown = 1 Green = 5 Second Ring Green = 5 Red = 2 Third Ring Brown = x10 = 150 ohms Yellow = x10,000 = 520k ohms Test of Color Rings First Ring is first digit Second Ring is second digit Third Ring is number of zeros Ring Black = 0 Brown = 1 Red = 2 Orange = 3 Yellow = 4 Green = 5 Blue = 6 Violet = 7 Gray = 8 White = 9 Resistor Value Examples Answer

44 44 Transistor NPN A Transistor is an Electronic Switch 12 Volt Battery 12 Volt Battery Computer can send a signal to turn on the transistor which then turns on the light NPN Transistor Light Mechanical Switch Circuit Transistor Switch Circuit Switch open Light off = 0 Switch close Light on = 1 Transistor come in different sizes depending on the amount of current and voltage required Switch Transistors

45 45 Draw, Label and Explain this Schematic

46 46 An integrated circuit (IC) consists of multiple transistors. The number of transistors can vary from just a few (circuits shown below), to over two billion that are in the latest Intel microprocessor. 6 Transistors in one IC This IC has 6 inverters An inverter contains 6 Transistors = 36 total Functions Inverters Gates Flip flops Counters Memory MPU Watch ICs Calculators ICs Microwave Timer ICs Radio ICs Dialer ICs Car Controller ICs Integrated Circuits

47

48 48 Microprocessor Integrated Circuit: 60,000 Transistors End of Class 1

49 49 Education & Certification Required for Engineering Careers Engineering Assistant 6 months to 2 years of Technical School during or after High School Entry-Level Design Engineer 4-year Bachelor of Science in Engineering Degree Senior-Level Design Engineer, Engineering Manager 4-year BS Degree, 2-year MS Degree 2-20 years experience Some Engineering Positions Require State Registration (P.E.) Professor, University or Industry R&D Laboratory Researcher Ph. D. or Sc. D. Degree in Physics or Engineering

50 50 US Numbers by Type From the American Society for Engineering Education, 2009 (http://www.asee.org)http://www.asee.org

51 51 US BS Engineering Graduates By School, 2009 (Source: ASEE)

52 52 US News & World Report 2011 US Undergraduate Engineering School Rankings (with Ph. D. Program) RankSchool ( * = public) 1Massachusetts Institute of Technology 2Stanford University (CA) 3University of California, Berkeley* 4California Institute of Technology 5Georgia Institute of Technology* 6University Of Illinois, Urbana-Champaign* University of Michigan, Ann Arbor* 8Carnegie Mellon University (PA) 9Cornell University (NY) Purdue University (IN)*

53 53 Starting Salaries Top Jobs for 2010 Bachelors Graduates (www.jobweb.com)www.jobweb.com

54 54 About Joe Mulcahey Before College –Built lots of Heathkits, installed an intercom and an alarm system in my tree house, performed various dangerous high-voltage experiments –Studied, passed FCC tests and became an amateur radio operator –Studied some more and passed more FCC tests, got a commercial radio operators license enabling me to work as a studio and transmitter engineer at a 50,000 Watt radio station in Hartford College –Co-op student at Raytheon in the Antenna and Microwave Department –Earned the BSEE and MSEE degrees from MIT in 1984 Raytheon (since 1981) –My specialty is designing and testing really big and expensive phased array radar antennas for missile defense –Raytheon is an industry leader in defense and government electronics, space, information technology, technical services, business aviation and special mission aircraft, with more than 71,000 employees world-wide, including over 30,000 engineers

55 55 About Len Barrett Learned Aviation Electronics in the Navy Worked in an Electronics repair shop CGR and Siemens: Serviced x-ray equipment, CT scanners and MRI scanners Got a business degree from Northeastern Currently at Aramark: Technology Manager in South Shore Hospitals Clinical Engineering Department

56 56 About Sean Mulcahey Eagle Scout with Gold Palm, 2009 –Merit Badges earned: Electronics, Engineering, Radio, Energy, Computers and 26 others Crew Guide, Venturing Crew 748 NEU Sophomore in Electrical Engineering Currently on co-op at Bose, in the Product Safety Laboratory –Test returned and not-yet-released products for safety –Take expensive and fragile audio equipment and set it on fire, apply massive overvoltages, shake and drop

57 57 Power Supply Power Equipment or Components for Test Volt-Ohm Meter (VOM) or Digital Volt Meter (DVM) Check AC & DC Voltages, Resistance, Opens/Shorts May also Measure Capacitance, Inductance, Gain, etc. Oscilloscope Graphs one Voltage vs. Time or vs. another Voltage Radio Equipment Testing Signal Generator Receiver Power Meter Spectrum Analyzer Graphs Voltage versus Frequency Network Analyzer Field Strength Meter Test Equipment Now go get some hands-on experience! End of Class 2

58 58 Safety Note: A Soldering Iron gets hotter than 300 F. Do not touch the soldering irons metal parts or you will receive a third degree burn A good solder joint depends on the following: 1) Solder iron must have a clean, well-tinned tip 2) Parts to be soldered must be clean 3) There must be a sound mechanical joint 4) Parts to be soldered must be well heated before applying solder 5) Wait approx. 5 seconds after soldering to allow strong mechanical joint to form Soldering

59 59 Place soldering iron so that it touches both the PC board and wire. The heat from the soldering iron will transfer to the PC board and wire at the same time. Iron Wire PC Board Iron Wire PC Board Iron Wire PC Board Wrong way Right way Solder melts at 310° F. The wire and PC (Printed Circuit) board must be the same temperature for the solder to melt on both items. Soldering – Heating Junction

60 60 When the board and wire are hot enough the solder will flow and create a cone shape. If the board is not hot enough the solder will be rounded on the board creating somewhat of a ball. The finishing solder should also be shiny. Clip extra wire at board level. Wire PC Board After 3 seconds place the solder on the tip of the iron, the wire and the PC board all together. The solder should flow to everything making a good connection. Wire Iron Solder PC Board Wire Iron Solder PC Board Right way Wrong way Soldering – Applying Solder

61 61 1.Use pliers to hold the component next to the lead to be unsoldered (If the lead is held with the pliers it will draw heat from the lead) 2.Apply soldering iron tip to PC board and wire 3.Either use solder wick or solder sucker to draw solder off the board, or simply pull wire from PC board when hot 4.The soldering iron will damage electronic components if left on device for greater than 15 seconds, so work quickly 5.Sometimes it helps to put more solder on the solder joint to improve the thermal conductivity 6.Clean the soldering iron tip and keep it shiny Un-Soldering

62 62 Wire Iron PC Board Iron Pliers With pliers, hold device close to lead that is to be unsoldered. As heat is applied from soldering iron, pull with pliers. With one side out, do the same on other side. PC Board Un-Soldering

63 63 PC Board LED Note Flat Edge +Red Black 1) Place components into PC board in the order recommended on instruction sheet 2) When components are placed into PC board, bend leads out slightly to keep parts from falling out, when the PC board is turned over for soldering. 3) Follow instructions as to proper orientation of components. Clip wire at board Wrong Correct Kit Assembly

64 64 Soldering Kit

65 65 From the Kit Manual

66 Anode of LED1 Q1 and Q2 are connected in a criss-cross fashion making a square wave oscillator running at about 1.5 Hz. The frequency is determined by C1 and R6. (Also C2 and R4.) 66 The Oscilloscope is displaying plots of voltage vs. time

67 C2 Negative, Q2 Base When Q1 conducts, Q2 gets turned off until the voltage at Q2 base rises above about 0.7V. C2 has to discharge through R4 for this to happen. This determines the time the multi-vibrator will stay in one state. 67

68 IC1 pin 2 & 6 IC1 is also an oscillator that drives the speaker at a frequency that we can hear. It oscillates at either the low tone of about 720 Hz or the high tone of about 980 Hz. C4 charges through R5 but discharges through R9. 68

69 IC1 pin 3 This shows pin 3 of IC1 that drives the speaker. This oscilloscope shot captured the 985 Hz tone. The output at pin 3 is a square wave (almost). 69 End of Class 3


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