Electronics Merit Badge

1. Electronics Merit Badge Old Colony Council Merit Badge University March 2012 Joe Mulcahey Len Barrett Sean Mulcahey jkm@alum.mit.edu http://www.mulcahey.org http://www.crew748.org Rev. S, 01MAR12 Based on the Electronics Merit Badge classes taught at the 2005 & 2010 National Jamborees

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

3. Safety with Electricity and Electronics

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 doesn’t kill you, you can still be badly burned from touching the wrong thing

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

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

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

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

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. 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 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! Static Electricity • Examples of static electricity: • Lightning • Combing hair • Walking across carpet and getting shocked • Pulling out scotch tape

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: • Kitchens: Stoves, ovens, mixer, etc. • Computers (the plug) • Lights in house • Home air conditioners

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: • MP3 players • Radios • Electricity in cars • Anywhere you use a battery for power

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

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

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 = 0.001 amp • microamps (mA) : 1 mA = 0.000001 amp, or 0.001 mA • nanoamps (nA) : 1 nA = 0.000000001 amp, 0.000001 mA, or 0.001 mA

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

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) : 0.001 volt • Microvolt (mv) : 0.000001 volt, or 0.001 mV • Nanovolt (nv) : 0.000000001 volt, 0.000001 mV, or 0.001 mV

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

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)

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. Ohm’s 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

23. More Ohm’s Law Different forms of Ohm’s Law: V = I x R : Voltage = Current X Resistance I = V / R : Current = Voltage / Resistance R = V / I : Resistance = Voltage / Current 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? + 10V 1000 Ω

24. Ohm’s Law Pie Chart If you know any two values, you can get the other two with these formulas

25. Bonus Ohm’s Law Question: Resistor Cube R R Resistances in series add: RTotal=2R Resistances in parallel divide: RTotal=R/2 What is the resistance between points A and B?

26. Where Did the Names of the Electrical Parameters Come From? Volts: Count Alessandro Volta (1745-1827), Italian Scientist Ohms: Georg Simon Ohm (1787-1854), German Physicist Amps: André-Marie Ampère (1775-1836), French Physicist Watts: James Watt (1736-1819), British Engineer Farads: Michael Faraday (1791-1867), British Physicist Henrys: Joseph Henry (1797-1878), American Physicist Other Units: Coulomb, Gauss, Joule, Tesla and of course Smoot

27. Smoot? What’s 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 364.4 smoots long "plus epsilon," but this has been recorded as 364.4 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 (170.18 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 NC Single Pole, Double Throw Switch (SPDT) W NO Capacitor Battery or Resistor Light Emitting Diode (LED) Ground Buzzer Fuse Lamp

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

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

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

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

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

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

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

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

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

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

39. Electronic Components Diode PN junction. Current flows in direction of arrow only 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 Switch Normally Open (n.o.) Normally Closed (n.c.) Anode (P) Cathode (N) n.c. n.o. LED Light Emitting Diode Slide Switch Can connect the center Pole to one of two Throws (SPDT) NPN (“Never Points iN”) PNP (“Points iN Proudly”) Meters Current Meter Voltage Meter Resistance Meter Bonus Question: Which type is the Transistor on the Electronics Merit Badge?

40. Resistor Color Rings A Resistor’s 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. A Fifth Ring, if present, could indicate reliability or temperature sensitivity Resistor Color Code Values Fourth Ring Brown = +/- 1% Red = +/- 2% Gold = +/- 5% Silver = +/- 10% None = +/- 20% First Ring Black = 0 Brown = 1 Red = 2 Orange = 3 Yellow = 4 Green = 5 Blue = 6 Violet = 7 Gray = 8 White = 9 Second 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

41. G-Rated Resistor Color Code Mnemonics • Black Brown Red Orange Yellow Green Blue Violet Gray White (Gold Silver None) • 0 1 2 3 4 5 6 7 8 9 • 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

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

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

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

45. Draw, Label and Explain this Schematic

46. Integrated Circuits 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. 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 6 Transistors in one IC

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

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