Electronics Merit Badge – Electronics is the science that controls the behavior of electrons so that some useful function is performed. (Electrons will be explained more fully later in this book.) Today, electronics is a fast-changing and exciting field.
The rapid growth of electronics started in the early 20th century when vacuum tubes were introduced and used to manipulate electronic signals.
This was something that could not be done with the telegraph and telephone circuits or the high-voltage transmitters of those days. Vacuum tubes allowed weak radio and audio signals to be amplified, or to be made louder or stronger, and be sent on radio waves.
Electronics changed even more dramatically in 1948 when the transistor, a small, low-powered, solid-state electronic device, was invented. Transistors are smaller than vacuum tubes, require less power to function, and are more reliable.
The development of the integrated circuit, or IC, advanced this technology further. ICs can contain tens of thousands of tiny transistors built onto a small piece of conducting material.
This allows for constructing and producing complex electronic circuits, which are more efficient than tubes in processing electronic signals. ICs are used in many products today, including computers, audio equipment, cell phones, appliances, and automobiles.
Now let’s see what are the requirements we have to meet in getting the electronics merit badge.
Electronics Merit Badge Requirements
- Describe the safety precautions you must exercise when using, building, altering, or repairing electronic devices.
- Do the following:
- Draw a simple schematic diagram. It must show resistors, capacitors, and transistors or integrated circuits, Use the correct symbols. Label all parts.
- Tell the purpose of each part.
- Do the following:
- Show the right way to solder and desolder.
- Show how to avoid heat damage to electronic components.
- Tell about the function of a printed circuit board. Tell what precautions should be observed when soldering printed circuit boards.
- Do the following:
- Discuss each of the following with your merit badge counselor
- How to use electronics for a control purpose
- The basic principles of digital techniques
- How to use electronics for three different audio applications
- Show how to change three decimal numbers into binary numbers and three binary numbers into decimal numbers.
- Choose ONE of the following three projects. For your project, find or create a schematic diagram. To the best of your ability, explain to your counselor how the circuit you built operates.
- A control device
- A digital circuit
- An audio circuit
- Discuss each of the following with your merit badge counselor
- Do the following:
- Show how to solve a simple problem involving current, voltage, and resistance using Ohm’s law.
- Tell about the need for and the use of test equipment in electronics. Name three types of test equipment. Tell how they operate.
- Demonstrate to your counselor how to read the colored bands of a resistor to determine its resistance value.
- Find out about three career opportunities in electronics that interest you. Discuss and explain to your counselor what training and education are needed for each position.
How to Earn the Electronics Merit Badge
The first step in earning your Electronics merit badge is to discuss the requirements with your merit badge counselor.
1. Learn About the Precautions
To fulfill requirement 1, learn about the precautions you should take when using, building, altering, or repairing electronic devices.
Many electronic components (parts) could be damaged if mishandled. Here are some basic safety precautions; there are more safety suggestions later on pamphlet.
As you read this pamphlet and work on the requirements, pay attention to safety and see whether you can add to this list. You can check more about electrical safety precautions.
2. Learn About the Schematic Diagrams
For requirement 2, study the chapter called “Schematic Diagrams. Choose a schematic diagram from the pamphlet or in this article, then copy it carefully with a pencil.
Your drawing must show resistors, capacitors, and transistors or integrated circuits. Use the correct symbols for these components, label all parts, and be prepared to tell the purpose of each component.
Show your drawing to your counselor and tell what you have learned.
3. Learn How to Solder
For requirement 3, learn how to solder and then practice soldering and desoldering wires. When you think you are ready, show your soldering skills to your counselor.
Be prepared to discuss soldering precautions, printed circuit boards, and possible heat damage to components when using a soldering iron.
4. Build Electronics Circuit
Requirement 4 is demanding but fun because you will actually build a working electronics circuit. Choose your project carefully.
Make sure that all the required parts are available at an electronics parts store, from a catalog, or over the Internet (only with your parent’s permission).
Also, consider what tools you will need. You can choose a project other than those in this article but check with your counselor first to make sure that the project is suitable.
After you are done with the project, show it to your counselor, explain how it works, and show your ability to read the schematic diagram.
For requirement 4 you will also learn the basic principles of digital techniques, how you can use electronics for control purposes, and about audio applications.
Learn the binary system to know how to change decimal numbers into binary numbers and binary into decimal.
5. Solve the Problem Using Ohm’s law
For requirement 5, you will need to solve a simple problem using Ohm’s law. You also should be able to discuss test equipment, the different types, and what they’re used for.
For the final requirement, study three career opportunities in electronics that interest you. Discuss with your counselor the education and training needed for each.
Tools for Electronics Work
The basic tools you will need for most of your electronics work are shown here. You can probably find some around your home and get others at an electronics parts store.
Electronic parts are called components, which comes from the word meaning to put together. An electronic circuit is composed of several interconnected components.
The leads on a component are insulated electrical conductors, such as wires, that connect to an electrical device.
For most projects, you can use any small-diameter solid or stranded hookup wire.
Some projects might also require very small wire. A magnifier or magnifying work lamp is recommended for examining the circuit board to check solder connections.
Most electronics parts stores have a selection of perforated circuit boards made especially for wiring electronics projects. Many come with small clips for mounting parts. These boards are ideal for building simple circuits.
You also will need an electric soldering iron, which you can buy at a hobby, electronics parts, or hardware store. The soldering iron in a beginner’s tool kit should be a 15- to 40-watt iron with a fine chisel tip.
Use 60/40 rosin-core solder (60 percent tin, 40 percent lead) that is marked for “electronic use.” Never use acid core solder. Most of the solder you will need will have a diameter of 0.03 inches.
You also should have a solder wick for desoldering a connection if you make a mistake or want to remove a component. Use a workbench for your project if you have one. If not, you can use a kitchen table, desk, or sturdy card table.
You will need to have good light and ventilation and access to power outlets. You also will need a few small boxes, trays, or jars to hold parts.
Buying Parts
Most electronics parts stores will have the components you will need for your project. If you do a project from scratch, you will have to buy the parts separately.
While you also can buy a complete project as a kit, many electronics kits found in retail stores are not soldering kits, and building a project from scratch is challenging and rewarding. Scratch projects can be inexpensive if you can scrounge for most of the parts.
However, a kit has a number of advantages. All the necessary assembly instructions and parts are supplied, including wire and solder.
Special parts, such as printed circuit boards, come with the kit. In addition, fewer tools are required because all necessary holes are pre-punched. Since the kit has been carefully tested, you know that the finished product will work.
A complete kit generally costs less than buying the parts separately. Investigate doing a project both ways before you invest your money.
Basic Electronics Theory
Before you learn about electronic components, let’s look at the theory behind electronics. Controlling electrons is the science of electronics. So, our study of electronics theory begins with the electron.
Also Read: Electricity Merit Badge Guide
1. Atoms and Electrons
To understand electrons, we must learn about the makeup of matter. All matter is composed of atoms, and an atom is composed of three elementary particles: electrons, protons, and neurons.
Negatively charged electrons revolve around the core (the nucleus) of the atom, which is composed of positively charged protons and neutral (not charged) neutrons.
Generally, a negatively charged electron is matched by a positively charged proton. For example, copper has 29 electrons revolving around a nucleus containing 29 protons.
A basic law of nature controls electrical charges. This law simply stated that unlike charges attract and like charges repel. This means a negative charge is drawn to a positive charge but pushes away from another negative charge.
This is called electrostatic force Normally, the positively charged protons hold the negatively charged electrons in place.
However, an electron sometimes breaks away from an atom because of an outside force, such as heat, light, magnetic fields, or chemical reactions.
Once freed, electrons can “float” among atoms. These free electrons what is important in electronics. Devices such as resistors, capacitors, and transistors are used to control the behavior of these free electrons.
2. Conductors and Insulators
Conductors act as a pathway for free electrons. Most metals are good conductors of electrons, so they can be used to “transport” electrons from one place to another.
Insulators act as walls or barriers, preventing electrons from flowing where we do not want them to flow. Insulators, for example, are used on most electrical wires to protecting us from electrical shock.
Copper, silver, and gold are popular conductors because they have a large number of free electrons.
As an example of how to make the electrons flow, picture a length of copper wire with one end connected to the positive terminal of a battery and the other end connected to the negative terminal.
The positive terminal attracts the negatively charged free electrons of the wire (remember: unlike charges attract) while at the same time the negative terminal repels the electrons.
The result is a flow of electrons through the wire from the negative to the positive terminal. This flow is called an electric current. An insulator works just the opposite.
In some materials, such as plastics and glass, atoms hold their electrons tightly. These materials have very few free electrons.
Therefore, if the length of an insulator is connected to a battery the same way the copper wire was attached, no measurable current would flow.
Also Read: Energy Merit Badge Guide
3. Current, Voltage, and Resistance
Here are some basic definitions of terms used in electronics. Current is the orderly movement of electrons through a conductor.
- Current is measured in amperes, amps, or the rate at which electrons move past a given point. One ampere is the movement of about 6 billion electrons past that point in one second. Voltage is an electrical pressure that can cause current to flow.
- Voltage forces are current to flow through a wire in much the same way that water pressure forces water to flow through a pipe. This electrical pressure can be caused by magnetism, chemicals, friction, light, or heat. The unit of voltage is the volt.
- The opposition to current flow is resistance. The resistance o material is mainly determined by how many free electrons it has. If the material doesn’t have many free electrons, it will have little or no current flow. The unit of resistance is the ohn. One ohm is the amount of resistance that will allow 1 ampere of current to flow when the applied voltage is 1 volt.
4. Ohm’s Law
Ohm’s law describes the basic relationships between current, voltage, and resistance. The formula for Ohm’s law is:
Voltage (volts) = Current (amperes) x Resistance (ohms)
To determine the current, the formula would be:
Current (amperes) = Voltage (volts) ÷ Resistance (ohms)
If you know the current and resistance, you can find out the voltage. For example, how much voltage is needed to force 2 amperes of current to flow through 10 ohms of resistance?
Ohm’s law tells us that we need to multiply our 2 amperes (current) by the 10 ohms (resistance) to arrive at the answer: 20 volts.
If you know voltage and resistance, you can figure out the current (Voltage + Resistance). Therefore, how much current will flow in a circuit having 5 ohms of resistance when 15 volts are applied?
15 volts ÷ 5 ohms = 3 amperes
With these formulas, you can solve simple problems involving current, voltage, and resistance.
5. Power
Another electrical quantity is power. Power is the rate at which work is done. The unit of electrical power is the watt and can be compared to the unit of mechanical power, called horsepower. One horsepower is equal to 746 watts.
The formula for power is :
Power (watts) = Voltage (volts) x Current (amperes)
When this formula is applied, you can determine the amount of power used by a circuit if you know the voltage and current. For example, how much power is used by a 120-volt toaster that draws 5 amperes:
120 volts x 5 amperes = 600 watts
The power used by the toaster is 600 watts. This power is used or dissipated, in the form of heat to toast the bread.
6. Resistance and Resistors
You have learned that when you apply a voltage to the ends of a conductor, it creates a current. Its strength depends on the applied voltage and the resistance of the conductor. The resistance of a conducting material depends on three factors :
- The kind of material
- The length of the material
- The diameter or area of the material.
Temperature also is a factor in resistance. In most materials, resistance is increased when the temperature rises and decreased if the temperature is colder. In most simple circuits, however, the temperature is not critical and is often ignored.
The kind of material is probably the most important factor in resIstance. Copper, for example, is a good conductor, while the iron of a similar size has a higher resistance. Carbon has even a higher resistance than iron.
The longer the conductor, the higher the resistance will be. For instance, if the length of a copper wire is doubled, the resistance will be doubled. As an example, a 60-foot length of copper wire might have a resistance of I ohm.
A same-sized copper wire that is 120 feet long would have a resistance of 2 ohms. Size is important, too. A thick conductor will carry more current and offer less resistance than a thin one. Think again of water pipes.
A large water pipe will allow more water to flow than a small one. When a current flows through a resistor a component that limits or opposes the flow of a current, work is being done to move the electrons. This work produces heat and warms the resistor.
The heat produced by an electric current: is the basis for the operation of many electrical devices and appliances such as heaters, toasters, stoves, and soldering irons. In a lightbulb, an electrical current causes a wire filament to become so hot that it glows to produce light.
Only a fraction of a current is needed to produce the light, so a resistor is used to limit the current or to develop a voltage. A resistor is designed to have a specific value of resistance, and resistors are available in a wide range of values.
Standard power sizes are 1/4 watt, 1/2 watt, 1 watt, and 2 watts. These values indicate the maximum recommended power that the resistor can dissipate. The higher the power rating, the larger the resistor.
7. Capacitors and Capacitance
A capacitor is a device that can store electrons or an electrical charge, that can be released at a later time. Imagine two sheets of aluminum foil (conduct ng plates) that are separated by a sheet of waxed paper (an insulator).
If you connect a battery to the two aluminum sheets, electrons will flow from the sheet that is connected to the positive terminal of the battery. Simultaneously, the same number of electrons will flow from the negative terminal of the battery to the other aluminum sheet.
The number of electrons that are transferred makes the voltage between the aluminum sheets exactly that of the connected battery. If the battery is removed, the aluminum sheets will remain in their charged state.
If there is no leakage through the waxed paper, the sheets will remain charged indefinitely Any two conducting plates separated by an insulator make up a capacitor. A capacitor can consist of many conducting plates with insulating separators.
Alternate plates would be connected to form interleaved stacks. The higher the voltage, the greater will be the amount of charge that is transferred from one plate to the other. The ratio of charge to voltage is defined as the capacitance of the capacitor.
Or you could also say that the “electrical size” of a capacitor is its capacitance, which is the amount of electric charge it can hold. The unit of capacitance is the farad.
However, is unit is too large for most practical capacitors, so capacitors are manufactured to measure millionths of a farad (microfarads) and trillionths of a farad (picofarads, which are micro-microfarads).
The insulators that separate conducting plates in a capacitor can be made of several materials, including ceramic materials, mica, certain types of paper, air, and oxide (a compound containing oxygen).
A popular capacitor has been the electrolytic capacitor. In this capacitor, the insulator is an extremely thin oxide layer. The leads of electrolytic capacitors are marked positive and negative. These indicate how the capacitor must be connected for proper operation.
8. Electron Tubes
The electron tube made the science of electronics possible. Although it largely has been replaced by transistors, it still has special uses.
A diode allows current to flow through it in one direction but not the other. It has two main electrodes, placed a short distance apart in a vacuum.
One electrode is called the plate the other is the cathode. A filament (or heater) heats the cathode. The cathode is made of a material that emits electrons when it is heated, so a cloud of electrons surrounds the heated cathode.
When the plate of the diode is connected to the positive side of a battery, electrons from the cathode will flow to the plate. As we have learned, the positive charge attracts the negatively charged electrons. Therefore, electrons can easily flow from the cathode to the plate.
9. Semiconductors
The word semiconductor is used to name a wide variety of electronic devices. Made of solid or liquid material, semi-conductors generally are able to conduct electricity more easily than an insulator, but not as easily as a metal.
The semiconductor diode performs the same basic function as the electron-tube diode. lt allows current to flow in one direction, but not the other. The diode consists of two different types of silicon crystals.
An impurity (some type of substance) can be added to one area of the silicon to control the silicon’s conductivity. The silicon is said to have been “doped” when it has been treated with atoms from an impurity.
These atoms combine with the silicon atoms in such a way that electrons float around freely inside the silicon. This type of silicon is called N-type (or negative-type). The N-type silicon is the cathode of the diode.
10. Integrated Circuits
An integrated circuit (1C) is a complete circuit in a single package. Transistors, resistors, diodes, and capacitors can be formed in a single chip of silicon, a semiconductor.
One chip can contain thousands or even millions of electronic components. Integrated circuits have revolutionized many fields, including communications, information handling, and computing.
They have reduced the size of devices while providing faster speeds and increased reliability. The individual components of ICs are extremely small and are assembled to a pattern that has been planned in advance.
A chip might look flat, but it has several layers for circuits. Switches control the electrical current through the chip. The switches manipulate the binary code (discussed below) with “on” and “off” switches.
The binary code is at the core of how a computer operates. Chips come in many different sizes, with millions of transistors being able to fit on chips the size of a postage stamp. Two basic types of IC are called linear and digital.
Linear circuits include amplifiers, oscillators, regulators, and other circuits used in TV sets, audio amplifiers, radios, and hearing aids. Digital circuits include memories and arithmetic circuits and counters in watches, calculators, computers, and video games.
11. Microprocessors
The microprocessor is a type of ultra-large IC. By 1971, the technique of making 1Cs had progressed to the point where enough computing power could be put on a single IC to form a tiny, primitive computer, or calculator.
The first microprocessor was born. Today, microprocessors can incorporate as many as 10 million transistors, plus components such as resistors, capacitors, diodes, and wires.
The microprocessor accepts input data, modifies that data in some way, and produces an appropriate output. The earliest application of the microprocessor was the calculator.
A calculator accepts numbers that the user enters on a keyboard, performs a mathematical operation on those numbers that the user desires, and then sends the result to a display.
Today’s microprocessors function as the central processing unit (CPU) of computers. They also are used in mary electronics systems such as cameras, printers, planes, and automobiles.
The microprocessor in an automobile, for instance, examines inputs from several sensors, makes decisions based on those inputs, and adjusts such things as the mixture of air and fuel and the timing of ignition firing.
The microprocessor’s most important aspect is that it can be programmed to perform an almost limitless number of applications.
