1. Electricity & Electronics Merit Badge
Class 1
Developed for the Electronics Merit Badge by Tim Hurd, Technical Manager for the Electronics Merit Badge, IEEE emertibadges project. Borrowed with permission and slightly modified by Bruce MacAlister, Technical Manager for the Electricity Merit Badge, IEEE emertibadges project.
The changes are some explanatory notes on volts and amps and the inclusion of a scout-build switch to meet Requirement 11 d. “Build a single-pole, double-throw switch. Show that it works”
See parts needed on next slide notes.
Name ______________________________
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Electricity Merit Badge Class National Scout Jamboree

2. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
CLASS 1 – What is Covered
Careers.
Basic electronics/electricity tools.
Safety and electronics/electricity.
Voltage and Current and Power
You will build and/or try:
Switches, lights, buzzers, leds.
Draw a circuit to turn on light.
Build circuit with circuit box.
You can get these slides from the Internet at
There are no slides on careers, but it should be easy to have a short discussion about kinds of engineers and kinds of work out there.
Parts for switch:
Wood block drilled with 3 holes
3 brass wood screws
3 wires with round connectors on one end and banana plugs on the other
1 paperclip
1 screwdriver
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Electricity Merit Badge Class National Scout Jamboree 2

3. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Equipment Used
Volt/Ohm/Amp Meter
Usually referred to as meter.
With this we can measure current, voltage and resistance.
Oscilloscope
Usually referred to as scope.
With this we can ‘see’ voltages.
This is very useful when voltage is changing, as a meter is no good to us when this is happening.
It is helpful to have examples of these 2 instruments in the class.
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Electricity Merit Badge Class National Scout Jamboree

4. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Computer
Computers are used heavily for
research, for drawing schematics,
for writing programs, for assisting
in fixing broken circuits, etc…
Frequency Generator
Frequency Counter
Circuit Boards
Frequency generator used to feed a radio a signal to test it
Frequency counter used to see what signal a radio transmitter – like your cell phone – is sending
Circuit boards are in everything, cell phones, watches, computers
Computer is heavily used for every day electronics design. Engineers write software to support hardware work, and this is done with computers as well.
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Electricity Merit Badge Class National Scout Jamboree

5. Two of the most important kinds of equipment
Your Brain
A brain assistant.
Emphasis is on importance of education in order to pursue an engineering degree. Yes, of course it is difficult, but so what? Challenging career leads to enriched life.
This is a difficult subject and requires hard work, but is well worth the effort.
Engineering can provide a lifetime of continuous discovery and learning.
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Electricity Merit Badge Class National Scout Jamboree

6. Safety with Electricity and Electronics
Does this look safe to you? Rightmost picture looks to be from Korea. What does that say about electricity safety in the US and other places?
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Electricity Merit Badge Class National Scout Jamboree

7. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Electricity Safety
High Voltage ( 120V AC or greater) – Safety mainly about not touching the wrong thing.
Current kills – Only 16 volts can kill when current flows through heart or head.
Ventricular fibrillation - Current passing through heart causes muscles to seize, causing death.
If the shock doesn’t kill you, you can still be badly burned from touching the wrong thing.
Safety for electricity is covered in the electricity merit badge, so I just mention it here.
Don’t fear electricity, learn when and how to handle it.
Next time you see an electric company worker on one of those tall hoists by a pole, notice what they are wearing:
Rubber shoulder pads to insulate from electricity
Thick insulating gloves
Orange insulation blankets draped over the electric lines
Shock can be avoided by being educated about potentially dangerous situations. Stay away from them!!!
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Electricity Merit Badge Class National Scout Jamboree

8. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
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 current to flow through heart (or maybe mouth, in this case).
The snake crawled under the fence. Once through the fence, it felt the shock from the electric fence, and turned to bite the fence.
This passed current through either its brain or heart, and that was it.
Its body made a connection from the fence to ground, and was being shocked.
The snake felt the shock and responded by striking at the source of its pain… the fence.
My guess is that once it bit the fence, it provided a better electrical path from the fence, though its heart, to ground.
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Electricity Merit Badge Class National Scout Jamboree

9. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Electronics Safety
Electronics generally uses lower voltages (less than 48 volts). You are usually working with DC battery voltage instead of AC line voltage.
You are usually more concerned with sparks from connecting 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, especially when they are plugged into a high voltage outlet.
I do not want to minimize the importance of safety in electronics. But, I did want to indicate that electronics is generally different than electricity due to the reduced voltages present, though AC voltage is present in equipment they may be using.
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Electricity Merit Badge Class National Scout Jamboree

10. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
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 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.
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Electricity Merit Badge Class National Scout Jamboree

11. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
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:
Lightning.
Combing hair.
Walking across carpet and getting shocked.
Pulling out scotch tape.
How to generate static electricity? Every strand of hair is repelling the next strand of hair, as they all have the same electrical charge.
Run comb through hair. The comb will attract paper.
Walk across a carpet and touch a doorknob.
Lightning occurs when a large enough charge accumulates between the bottom of a cloud and the earth, such that an ionization path is created between the two, and electrons flow…
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Electricity Merit Badge Class National Scout Jamboree

12. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
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.
AC power is present in the home.
Pay attention to safety around AC power.
One idea to illustrate AC power is to get a scout to walk in one direction and then turn around and walk in the other direction. Each time he passes the instructor, he reaches out with his hand and pushes on the instructors hand. Though current flows in 2 directions, it is reasonably easy to see how it can be used to do electrical work.
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Electricity Merit Badge Class National Scout Jamboree

13. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Types of Electricity
Direct Current (DC)
Type of electricity used in most, if not all 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.
We are talking batteries. Through a chemical reaction, batteries provide a flow of electrons --- current flow.
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Electricity Merit Badge Class National Scout Jamboree

14. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Electrical Terms
Current
It does the work of spinning motors, lighting bulbs
It is measured in AMPS, abbreviated A
The symbol used in math is I (eye)
Voltage
The pressure that pushes the current
It is measured in VOLTS, abbreviated V
The symbol in math is E
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Electricity Merit Badge Class National Scout Jamboree

15. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Basics of Electronics
Current: Defined as “flow of electrons”.
We will use positive flow, not electron flow when we talk about current.
Current: Units of current is AMPS.
Current: Electrical symbol for current is I (eye).
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Electricity Merit Badge Class National Scout Jamboree

16. 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 current is flowing in the wire.
Different pipe diameters illustrates different resistance to water flow, which correlates to different resistor values.
Get 1 scout to walk across the room. Now, get 2 scouts to walk across the room.
The scout is an electron, and by walking, is equal to current flow. Two scouts walking are two electrons, and are doubling current flow. I know this is hokey, but can be used when it makes sense during the class.
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Electricity Merit Badge Class National Scout Jamboree

17. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Voltage
Volts is the electrical force that causes
electrons (current) to flow.
Voltage can also be thought of as the electrical pressure that pushes electrons in a wire.
Units for voltage is VOLTS.
The symbol for voltage is E.
The schematic symbol for voltage is
generally shown as a battery
GND
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Electricity Merit Badge Class National Scout Jamboree

18. 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 current flow is small.
You can increase water (current) flow by making the pipe larger as well.
Gravity provides the force for water (current) to flow.
This illustrates a larger voltage, so current flow is larger.
You can increase water (current) flow by making the pipe larger as well.
This is a very important concept to get across. Voltage, current and resistance are the basis for this class.
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Electricity Merit Badge Class National Scout Jamboree

19. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Resistance
Resistance is the electrical property of a substance to resist the flow of electrons.
The units of resistance is OHMS (Ω).
The symbol for resistance is R.
The schematic symbol is
The larger the resistance, the more resistance to current flow.
The larger the resistance, the less current, given the same voltage in the circuit.
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Electricity Merit Badge Class National Scout Jamboree

20. 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
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Electricity Merit Badge Class National Scout Jamboree

21. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Ohms Law
E = I x R : Volts = Current x Resistance
Units
Volts is in volts
Current is in amps
Resistance is in ohms
This is really, really important. If you understand ohms law, you have a really good understanding of basic electricity.
Talk about how easy this equation is to remember and to use.
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Electricity Merit Badge Class National Scout Jamboree

22. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
Electronic Symbols
Single Pole, Double Throw Switch (SPDT)
Battery
Capacitor or
Resistor
Light Emitting Diode (LED)
Buzzer
Ground
These symbols will be used when drawing and wiring up the circuit we are going to do next.
Fuse
Lamp
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Electricity Merit Badge Class National Scout Jamboree

23. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
CIRCUIT DIAGRAM (SCHEMATIC)
FLASHLIGHT
SWITCH
LAMP +
GROUND
GROUND
This simple schematic is the circuit of each flashlight. Place emphasis on ground, so that it is fully understood that ground = 0 volts.
TWO GROUND SYMBOLS IS THE SAME AS CONNECTING WITH A WIRE
GROUND = 0 VOLTS
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Electricity Merit Badge Class National Scout Jamboree

24. Put On The Safety Glasses
You will be working with sharp, pointy objects
We don’t want you poking something into your eye.
There is one set of glasses for each scout
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Electricity Merit Badge Class National Scout Jamboree

25. Build SPDT Switch with a Paperclip
Use brass screws, paperclip, wires to build switch
Which color for which connection is not important
SPDT means Single Pole Double Throw
Simple switch where paperclip is moved from one pole to the other to send power to the connected device.
Differently colored wires used to easily tell which is the common (W on the circuit box) and which are NC and NO
Requirement 11 d
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Electricity Merit Badge Class National Scout Jamboree

26. Use Paperclip Switch in Next Diagrams
Use next two slides as the connection guidance
Requirement 11 d
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Electricity Merit Badge Class National Scout Jamboree

27. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
CIRCUIT CONNECTION BOX
Wire circuit to use switch to turn on lamp. +
SPST
FUSE W
BATTERY - NO NC
GND = 0V
Diagram just to get them started.
Have them figure out how to connect.
Advisors help the scouts make sense of plus (+) and minus (-), the idea of a completed circuit for current flow.
WHEN INSERTING AND REMOVING THE WIRES, MAKE SURE THEY GRAB THE WIRES BY THE PLASTIC HOUSING, NOT BY THE WIRE ITSELF.
Some of the connections on this example are already made, to show how to use the wiring kit.
Draw the circuit before wiring it up. Talk about how the circuit works.
SWITCH POSITION DOWN, IS NORMALLY OPEN.
SWITCH POSITION UP, IS NORMALLY CLOSED.
LAMP
BUZZER
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Electricity Merit Badge Class National Scout Jamboree

28. Electricity Merit Badge Class 1 - 2010 National Scout Jamboree
CIRCUIT CONNECTION BOX
Wire circuit to use switch to turn on lamp AND buzzer. +
SPST
FUSE W
BATTERY - NO NC
GND = 0V
Diagram just to get them started.
Have them figure out how to connect.
Advisors help the scouts make sense of plus (+) and minus (-), the idea of a completed circuit for current flow.
SWITCH POSITION DOWN, IS NORMALLY OPEN.
SWITCH POSITION UP, IS NORMALLY CLOSED.
Draw the circuit before wiring it up.
LAMP
BUZZER
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Electricity Merit Badge Class National Scout Jamboree

29. Now Use Factory-Made SPDT Switch
Do the two prior diagrams with the built-in switch.
Point out how the factory-made switch is not as rickety as the paperclip switch.
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Electricity Merit Badge Class National Scout Jamboree