From Proprofs

Welcome to The Complete Introduction to Electronics Guide! One of the most difficult parts about being in any technical field - including IT, broadband/phone services, or even appliance repair - is that you are expected to know a certain bit about electronics and electricity beyond what you were probably trained for in your specific field. This can be very troubling at times when you are trying to fix a problem that is basically electrical in nature. From basic concepts in electricity to the principles of work and power, this guide is designed to help you learn some of the basics of electronics while keeping things simple and in layman's terms so that terminology is easy to understand and concise. With this guide, your electricity-related woes should be gone for good. 

Acknowledgments A special thanks to bobby1234 for being the chief author of this guide, for conceptualizing it, contributing to it and for making it available on the wiki. Without Bobby's effort this guide would not be possible.

Contents 1 The Very Beginning 2 DC Electronics 3 Current 3.1 Current flow 3.2 The electric circuit 3.3 Measuring current 4 Voltage 4.1 Producing EMF 5 Batteries 6 Connecting batteries to make types of circuits 7 Voltage rise and drops 8 Resistance 8.1 Resistors 8.2 Connecting resistors 9 Ohm's law 10 Power 11 Magnetism 11.1 Electricity and magnetism 11.2 Induction 11.3 Electromagnetic and magnetic applications 12 Electrical measurements 12.1 Understanding how a multimeter works 13 DC circuits 13.1 Simple circuits 13.2 Voltage dividers 13.3 Bridge circuits 13.4 Laws and Theorems of Electronics 14 Inductance and Capacitance 14.1 Inductance 14.2 Capacitance 14.3 Capacitors 14.4 RC time constants 14.5 Capacitors in circuits 15 AC Electronics 15.1 The importance of alternating current 15.2 Generating AC 15.3 AC values 15.4 Waveforms 15.5 Resistance in AC circuits 16 Capacitive circuits 16.1 Capacitors and Capacitance 16.2 Capacitors in AC circuits 16.3 RC circuits 16.4 Applications of Capacitive circuits 17 Inductive circuits 17.1 Inductors and Inductance 17.2 Inductors in AC circuits 17.3 Applications of Inductive circuits 18 Tuned circuits 18.1 Resonance 18.2 Series Resonance 18.3 Parallel Resonance 19 Transformers 19.1 Transformer action 19.2 Transformer theory 19.3 Transformer Applications 20 Motors 20.1 DC motors 20.2 AC motors 20.3 Motor speeds 21 AC Home Applications 22 Concepts of Electronics 23 Semiconductors 24 Semiconductor fundamentals 24.1 The importance of semiconductors 25 Diodes 25.1 Zener diodes 25.2 Tunnel diodes 25.3 Varactor diodes 25.4 High frequency diodes 25.5 Light Emitting diodes 26 Transistors 26.1 Bipolar transistors 26.2 Field effect transistors 27 Thyristors 27.1 Silicon controlled rectifiers 27.2 Bidirectional Triode Thyristors 27.3 Unijunction Transistors 28 Integrated circuits 28.1 Importance 28.2 Application 29 Optoelectric Devices 29.1 Basic principles of light 29.2 Light sensitive devices 29.3 Light emitting Devices 29.4 Liquid crystal displays 30 Digital Techniques 30.1 The numbering system 30.2 Binary codes 30.3 Data representation 31 Digital Logic Circuits 31.1 logic gates 32 Digital Integrated Circuits 32.1 Logic characteristics 32.2 Transistor-Transistor Logic 32.3 Emitter-coupled Logic 32.4 Metal Oxide Semiconductor Integrated Circuits 32.5 Integrated Injection Logic 33 Digital Troubleshooting 33.1 Typical problems in digital circuits 33.2 Digital IC problems 33.3 Measurement Tools 34 Acronyms of Electronics 35 Charts/Diagrams 36 Safety

[edit section] The Very Beginning

You can not begin to understand the hows and whys of electronics until you understand the basic principles in which is was founded (everyone learned this in their high school science class) so this is just a refresher.

• Matter-Is anything that has weight and takes up space and exist in three states:

1. Solids. 2. Liquids. 3. Gases

• Elements-Are the basic building materials from which all matter is constructed.

• Compounds-Are composed of two or more Elements.

1. Compounds can be reduce to their smallest particle called a Molecule and still retain the characteristics of a compound.

• Atoms-Are the smallest particles to which an element can be reduced and consist of three things:

1. Electrons. 2. Protons. 3. Neutrons.

• Nucleus-This is the center of an atom and is composed of Protons and Neutrons.

• A balanced Atom-Is on the has an equal number of Protons and Electrons and is said to be in it's Normal Balanced or Neutral State.

• Only the Protons and Electrons contain an electrical property, the Neutron is neutral and does not contain an electrical charge.

1. Protons contain a Positive charge. 2. Electrons contain a Negative charge.

• Electrostatic Force-This is what holds the Electrons in orbit around the Nucleus and keeps it from flying off into space.

• The laws of electrical charges state: Likecharges repel and Unlike charges attract. In simple terms this means that two Negatives or Positive charges repel each other, but a Negative and Positive charge attract to each other.

• Ion-Is an atom that is no longer in it's neutral state. There are Positive and Negative Ions.

• Ionization-The process of changing an atom into an Ion.

• If an Ion losses an Electron and now has a greater number of Protons the net charge is now Positive. If it gains an Electron and now has a greater number of Electrons than Protons the net charge will be Negative.

• Actions of electrostatic charges There are three ways electrostatic charges develop.

1. Charging by friction. 2. Charging by contact 3. Charging by induction.

[edit section] DC Electronics

• Learning about Direct Current Electronics and Circuits.

• As we will not go into a great deal of depth and explanation in some of these tutorials for the simple fact that it is not designed to teach you how to design some circuits. These tutorials are designed to give you the basic knowledge, principles, concepts and understanding of how and why some circuits are used.

[edit section] Current

• Current always flows from Negative to Positive this is a very important law to remember.

• In electronics the voltage will always be expressed as the letter E and current will always be expressed as the letter I and resistance will always be expressed as the letter R.

• An important law to always remember is that current will ALWAYS seek the quickest and easiest way to ground this means that if you are working on an electrical circuit and you do not have it properly grounded and you touch or come into contact with components that have power YOU NOW HAVE BECOME GROUND and current will flow through your body to ground.

[edit section] Current flow

• Current-The flow of electrical charges from one point to another.

• All Atoms contain Orbital Shells which Electrons orbit around the center of the Atom. The four shells are the most important and they are:

1. The First Shell which contains 2 electrons. The Second shell can hold up to 8 electrons. The Third Shell can hold up to 18 electrons. The Forth Shell can hold up to 32 electrons. The orbiting shells start from the closest to the outer most in that order.

• Valence Shell is always the outer most shell and the electrons that orbit in this fourth shell are called Valence Electrons.

• Electrons that are in the fourth shell are furtherest away from the nucleus and they can be freed more easily to accomplish work.

• Conductors-Material that has large numbers of free electrons are called conductors, because they conduct an electrical charge very easily.

• Insulators-Material that has very few numbers of free electrons are called Insulators, because they do not have a large number of electrons to move about.

• Semiconductors-Elements that have an average number of 4 electrons in their valence shell are called semiconductors, because they are neither good conductors or insulators.

• Picture of a Direct Current waveform

• It is important to remember not to confuse this with an alternating wave form because the DC wave form does not flow below the line and only flows in one direction.

[edit section] The electric circuit

• An electrical circuit must consist of three important items:

1. A Power source. 2. A load. 3. A conductor.

• A load-Is anything in a circuit that performs a function, for example a light bulb is considered the load because it performs a specific function.

• Voltage-EMF is the force that moves electrons and voltage is the unit of measure for this principle.

• A switch-In any electrical circuit there must be a device that stop and starts the flow of electrons and this device is called a switch. When a switch if in the open position no electricity flows through the circuit and when the switch is closed electricity can flow freely through the circuit.

• Schematic diagram-Is a drawing in which symbols are used to represent circuit components. Electricians and Engineers use these to reduce and simplify blue prints for the components they are going to install in a building, house, etc. Each electronic component has it's own specific symbol to represent it.

[edit section] Measuring current

• A Coulomb-Is the unit of measure for electrical charge and is equal to 6.25 x 10 to the eighteenth power electrons or 6,250,000,000,000,000,000.

• Ampere or amp-This is the unit of measure for current. An ampere is equal to 1 Coulomb per second. This means if 1 coulomb flows pas a given point in one second then the current past that point is equal to 1 Ampere or amp.

Expression of amount of Amperes for a given time

Equation	Value
Coulombs divided by seconds =	Amperes

• Milliampere (mA)-A smaller measurement of amps. Milliamps is one thousandth (.001) of an amp.

• Microamp (uA)-Is one millionth (.000001) of an amp.

• Ammeter-An ammeter is a electrical device that measures current flow, more specific it measures amps.

• Series Circuit-Is a circuit that has only one current path.

• Rules to remember when using a meter: 1. Every meter has a minimum and a maximum measurement range, when using a meter you must make certain that the current will not exceed the maximum reading on the meter. 2. When preparing to take a measurement it is important to disconnect or shut off the power source of the circuit you are going to test. 3. Break the circuit at the point where you are going to be testing the circuit and must be in series with the circuit. 4. A meter has two terminals one labeled Positive and one Negative, it is important that current flow from the negative lead to the positive lead to observe Polarity (meaning that the negative lead is connected to the conductor that leads to the negative lead and the positive is connected to the conductor that leads to the positive lead). 5. Now that your meter is connected properly you can now restore power to the circuit in which you are testing and observe the reading.

[edit section] Voltage

• Voltmeter-Is a device used to specifically measure voltage in a circuit.

• Electromotive force or EMF-The force that moves electrons.

• Voltage-Is the unit of measure of Electromotive force.

• Potential Difference-Is another name for electrical force.

• Short-A short in essentially a circuit that has a defect that allows current to find another way to flow and is potentially dangerous to work on, so extreme caution should be taken and power completely turned off at the breaker box or power source.

To explain this a bit more we say that the potential to move electrons exists between any two unlike charges and remember that unlike charges tend to attract. If two unlike charges are given the opportunity electrons will flow from one to the other.

• Potential-Refers to the fact that there is always a potential to do work. This is why it is very important to respect electricity because even if you think a line is off there is always the potential that there could be a short and current is still flowing through the line and could deliver a deadly shock.

• Joule-The metric unit measure of energy and one Joule is equal to 0.738 foot-pounds.

• Foot-Pounds-Is the amount of work required to lift one pound a distance of one foot.

The different voltages

Unit	Value
Millivolt equals	1/1000 volt
Microvolt equals	1/1,000,000 volt
Kilovolt equals	1000 volts
Megavolt equals	1,000,000 volts

Determining Voltage

Equation	Result
Power(P) divided by Current(I) =	Voltage(E)
Current(I) x Resistance® =	Volts(E)

[edit section] Producing EMF

• EMF is produced when an electron is forced from it's orbit around the atom which produces energy in the form of electricity.

• There are six main ways to produce EMF and they are the following:

1. Magnetism and happens when a conductor moves through a magnetic field forcing electrons to react and move. 2. Chemical a good example of this is batteries, because batteries contain Sulfuric acid and water called an Electrolyte. The Sulfuric acid breaks down into Hydrogen and Sulfate and the Hydrogen atom gives up electrons producing energy. 3. Friction I think everyone knows how friction works if you have ever walked across carpet and then touched the metal door knob which produces A Static Charge Buildup. If you rub a conductor on something, electrons will transfer to the conductor and thus creating an electrical charge in the conductor. Producing electricity from friction is also know as The Triboelectric effect. 4. Light can be converted into electrical energy. A good example of this is Solar Cells and when light is converted into electricity it is also known as The Photoelectric effect. More details on how this happens will be explained further in this tutorial. 5. Pressure which can be produced when certain materials are subjected to pressure. This process is also known as The Piezoelectric effect. 6. Heat can also be converted into electricity with a device called a Thermocouple. The process for converting heat into electricity is also know as The thermoelectric effect.

[edit section] Batteries

In this section we will discuss the different types of batteries and give some details about each.

• Battery is a combination of two or more Electrochemical Cells. Everyone commonly calls batteries by their store name, but in Electronics they are known as Cells. There are two basic types of cells: One type can be Recharged and is called a Secondary Cell and the other type is called a Primary Cell and can not be recharged.

• Dry Cell-An example of a dry cell is the everyday flashlight batteries you buy at the store and the reason they are called dry cells is because they contain a moist chemical paste in them and do not contain a direct liquid. These cells still contain the same chemicals as do liquid filled batteries, but because of the paste they can be used in various positions without fear of the contents spilling out.

• Voltage of dry cells is not determined by the size of the battery. It mainly depends on the materials used in the electrolyte and electrodes. The voltage is determined by the electrochemical reaction with it. The only relation to the size of a dry cell is that the larger the cell the more electrolyte and bigger electrode can deliver a greater amount of electrons per period of time. To explain this in easier terms it basically means that all batteries deliver the same amount of voltage 1.5 volts but depending on their size determines how long they will last for any given period of time.

• Lead Acid Batteries Contain a liquid consisting of sulfuric acid and water and can only be used in the up right position because the contents would leak out. A lead acid battery example is your car battery and the main advantage this type of cell has over most dry cells is that it can be recharged.

• Nickel-Cadmium battery or (NICAD) for short-These batteries are made a bit different from the others we have discussed with a different bonding process and chemicals, but still serve the same purpose. NICAD batteries have a few differences than other batteries. 1. They are completely sealed and rechargeable 2. Unlike other batteries than slowly reduce in voltage over their life span, NICAD cells deliver a constant voltage throughout the remainder of their life span. 3. With other rechargeable batteries when a recharge takes place if affects the electrolyte concentration inside it, but with the NICAD this process does not happen and the electrolyte remains relatively the same. The only main disadvantage of NICAD batteries over the other types is the price which is considerably higher.

[edit section] Connecting batteries to make types of circuits

• This section will be discussing how to connect batteries in a circuit to make different types of circuits. This is a easy way to explain how circuits are designed and will play an important part throughout learning about electronic circuits and how they function and the different properties they have.

• In a circuit batteries can be connected in ways to increase either the Voltage or the Current.

• Series Aiding connection-In a series aiding configuration the power source ,in this case we will use batteries, the batteries are connected so that they are inline one behind the other which increases the overall voltage produced by them. If for example you take three 1.5 volt batteries and you connect them into a circuit and add up the total voltage you would take 1.5 x 3 = 4.5 volts for the total amount of voltage in that circuit. Each individual battery produces 1.5 volts so by placing them one behind the other you increase that 1.5 volts by 3. In other words with a series aiding connection, the total voltage across the battery is equal to the sum of the individual values of each cell.

Series circuit

• Parallel connection-In the previous paragraph you learned that a series aiding circuit can increase the voltage, but it does not increase the amount of current produced in the circuit. With a parallel connection the batteries are connected in a side by side manner which will increase the amount of current in a circuit. In a parallel circuit voltage is not increased but the current is. If you use 3 1.5 volt batteries and connect them in a parallel circuit the total voltage is still only 1.5 volts, but the current is now three times the amount.

Parallel circuit

• Series-Parallel connection-This type of connection has the best of both worlds. It increases the voltage and the current produced in the circuit. This time the batteries are aligned one up, one down, one up, one down and so forth. If you have ever noticed when you open most hand held video games the battery terminals has the positive or negative terminals facing opposite of each other in succession. If you take 9 batteries and you connect 6 of them where all the positive leads are connected and all the negative leads are connected you have a series circuit, now by connecting the other 3 batteries by connecting the positive to the negative for all three of them to the other 6 batteries you now have added a parallel circuit into the equation. That is why it is called a series-parallel circuit and you have now increased your current x 2 and your voltage x 3.

Series-Parallel circuit

[edit section] Voltage rise and drops

• During your experience with electronics and dealing with circuits and components you will encounter differences in voltages and currents. In this section we will discuss voltage rise and drops.

• Voltage Rise-Is basically any EMF that is introduced into a circuit by a voltage or power source. Voltages tend to remain constant unless a load is introduced into the circuit as long as there is a voltage or power source to provide electrons to flow.

• Voltage Drops-Is the removal of energy from a circuit. One difference between voltage rises and drops is that the voltage drop occurs only when current flows through the load.

• Voltage drops can be determined across the load if the energy consumed by the load is known (in joules) and the number of electrons through the load (in coulombs).

Equation	Result
Joules divided by coulombs=	volts
10 joules / 2 coulombs =	5 volts

• A law of voltage drops are equal to the sum of voltage rises-If you have a voltage rise of say 10 volts in a circuit and a load that consumes 10 volts of energy, then the voltage drop is 10 volts. So in simple terms, if you have loads that are either equal or not equal to the amount of voltages they consume the principle will always be the the following: The sum of the voltage drop will always be equal to the amount of the voltage rise or the amount of voltage produced by the power source.

[edit section] Resistance

• Resistance-Is defined as opposition to the flow of current.

• Ohm-The unit of measure for resistance.

• Basic Concept of Resistance = One Ohm is the amount of resistance that will allow one amp of current to flow in a circuit to which one volt is applied.

• Specific resistance or Resistivity-Every kind of material has it's own properties and it is these properties combined with shape, size, length and temperature that determines the materials resistivity or specific resistance.

• Conductance-This is the opposite of resistance because if a material is a good conductor it allows electrons to flow easily with little resistance.

• mho-Is the unit of conductance and is represented by the letter G. Since conductance is the opposite of resistance mho is actually ohm only backwards.

• Factors that determine resistance:

• Length-The resistance of a conductor is directly proportional to it's length. This means that the longer the conductor, the more resistance it will have or the shorter the conductor the less resistance it will have.

• Cross-sectional area-The resistance of a substance is inversely proportional to it's cross sectional area. This means that the thicker the substance the less resistance it will have or the thinner the substance the more resistance it will have.

• Temperature-In most materials an increase is temperature also causes and increase in resistance and these materials are said to have a Positive temperature coefficient. There are a few materials that do not respond in this ways and they are said to have a Negative temperature coefficient because their resistance decreases as temperature rises. Materials that do not have a change in resistance with temperature are said to have a Constant temperature coefficient.

• Thermistor-Is a device that uses the effects of temperature to a great advantage. It is a special type of resistor that changes resistance when it's temperature changes.

As you might know there are many different types of wire that is used in circuits as conductors with copper being the most widely used.

[edit section] Resistors

• Picture showing numerous resistors

• Resistor-Is a component that has a certain specified opposition to current flow or resistance.

• Types of resistors:

Wire wound-This type of resistor is usually made from nickel-chromium alloy with a resistance wire wrapped around the middle of the conductor with ceramic ends. This type of resistor is generally used in circuits with high amounts of current flowing through it and high amounts of power must be dissipated.

Carbon-composition-Since carbon is neither a good conductor nor insulator these are also called semiconductor. They have a protective non conducting coating with leads extending from both ends to attach into a circuit and are inexpensive and at one time the most widely used in electronics.

Deposit-film-These have replaced the carbon-composite resistors as the most widely used resistors to date. They are have a deposited film outer coating (which looks and feels like plastic)that is an insulator with leads extending from both ends to attach in a circuit. They are also inexpensive and These types of resistors is what you will see in today's electronic circuits.

• Resistors have three important ratings:

1. Resistance in ohms 2. Tolerance as a percent 3. Wattage in watts

• Tolerance-Is expressed as a + or - on the resistor package and represents a percentage. Tolerance in this forms means that that specific resistor can withstand it's power rating +/- that percentage without failing.

Most resistors used to day have color code bands on them that can be are used to determine the amount of resistance offered by that specific resistor. These bands will be different colors that represent different values in a sequential order beginning with the band that is the closest to the outer most edge of the resistor.

Color Code Bands

Color	Band 1 first #	Band 2 second #	Band 3 Multiplier	Band 4 Tolerance
Black	0	0	1
Brown	1	1	10
Red	2	2	100
Orange	3	3	1,000
Yellow	4	4	10,000
Green	5	5	100,000
Blue	6	6	1,000,000
Violet	7	7	10,000,000
Gray	8	8	100,000,000
White	9	9	1,000,000,000
Gold			0.1	+/- 5%
Silver			0.01	+/- 10% to +/- 20%

• To simplify how to use this chart we will take for example you have a resistor that has two red bands. When you look at the chart you see the first box states 2 and the second box states 2, so we start by putting them together which gives you 22. Now we look at the third box which gives you the multiplier so 22 x 100 = 2200 this means that the resistor has a value rating of 2200 ohms. Now you can look at the fourth box to see what the tolerance value for that resistor is by looking to see what color the fourth band is on the resistor. For example: the fourth band is gold, so looking at the chart you see that gold is rated at Plus or Minus 5% so this tells you that the over all 2200 ohms is plus or minus 5% of it's resistance value. Resistors rarely are exactly the value indicated on the resistor so that is why they have a fault tolerance.

• Wattage rating for resistors-Is the maximum amount of power or heat that the resistor can dissipate without being damaged.

Carbon composite resistors generally have a wattage rating of 1, 1/2, 1/4 watts are the most common.

• Variable resistors-Are resistors whose values can be increased or decreased in one way or another. A good example of this is the volume control on your average TV set, because you can increase or decrease the sound level by adjusting knob or using a remote.

• Fixed resistors-These are resistors that have a set value and cannot be changed, which you will find in most electrical circuits on the circuit board.

• Potentiometer or POT-Is basically a variable resistor that has usually three terminals that changes the value of the resistance and is also a variable type resistor just with a different construction.

• Sliding contact resistor-This resistor uses a sliding contact bar to adjust the resistance value and is used in high power applications where the resistance value must be initially set or occasionally reset.

• Another good example of a variable resistor is your basic dimmer switch in your home where you push it in one to turn the lights on and then you can turn the knob clockwise or counter clockwise to adjust the level of lighting in your room and then you push it again to turn off the light.

[edit section] Connecting resistors

• As discussed earlier in connecting batteries in different types of circuits, we will discuss connecting resistors in much the same way.

• Resistors in a series circuit-Are connected in a series circuit end to end, that does not mean they are one right after another, but all current flows through each of the resistors on a single path.

• Finding the total value of resistors in a series circuit-To find the total value of resistors in a series circuit is rather easy. Since current must flow through all resistors you simply add the value of each resistor together to obtain the total resistance in a series circuit.

Finding Total Resistance in Series

Equation	Value
R1 + R2 + R3 =	Rt or resistance total

• Rt is the short representation of Total resistance.

• Example: Say you have three resistors R1 (the first resistor)has a value of 10 ohms and R2 (the second resistor) has a value of 20 ohms and R3 (the third resistor) has a value of 30 ohms. To find the Rt (total resistance) you add the value of each resistor together. 10 ohms + 20 ohms + 30 ohms = Rt of 60 ohms.

• Resistors in a parallel circuit-Again as before in a parallel circuit components are connected across each other instead of inline like in a series circuit.

• Total resistance in a parallel circuit-To find the Rt in a parallel circuit you must take into consideration that current now has another path to flow instead of one path as in a series circuit.

Finding total resistance in a parallel circuit

Equation	Value
R1 x R2 divided by R1 + R2 =	Rt

To explain this you must take R1 x R2 to get your first value, then you do the same thing except this time you take R1 + R2 to get your second value. Now that you have both values you must take the value from your first calculation say R1 has a value of 15 ohms and R2 has a value of 10. 15 ohms x 10 ohms =150 ohms. Your second calculation are the same except you add so 15 ohms + 10 ohms = 25 ohms. Now to get your Rt you take 150 ohms divided by 25 ohms = 6 ohms.

• If you have more than two resistors in a parallel circuit the calculation formula changes slightly and is represented below.

Calculating more than two resistors in a parallel circuit with different values

Equation	Value
1 divided by 1 divided by R1 + 1 divided by R2 + 1 divided by R3=	Rt

• Example: If you have three resistors in a parallel circuit you must take Each resistor's value and divided that into 1 and then you do the same for all the other resistors and then add the values together and then divide that total into 1 again. R1 = 100 ohms divide that value into 1 = .01 ohms + R2 = 100 ohms and divide that into 1 = .01 ohms + R3 = 400 ohms divide that into 1 = .0025 ohms. Now add .01 + .01 + .0025 = .022 ohms. Now 1 divided by .022 ohms = Rt 45 ohms.

• If resistors in a parallel circuit all have the same value- The formula would be the following:

Equal value resistors in a parallel circuit

Equation	value
Values of one resistor divided by the Number of resistors in parallel =	Rt

• Example: You have four resistors in a parallel circuit with each resistor having the same value of 20 ohms. Since they all have the same value you would simply take the value of one resistor 20 ohms and divide that by 4 because you have four resistors. 20 divided by 4 = Rt of 5 ohms.

• Ohmmeter-Is a device used to specifically measure resistance.

• In order to test a resistor properly, you should remove it from the circuit in order to get an accurate reading.

[edit section] Ohm's law

• Ohm's law defines the way in which current, voltage, and resistance are related.

• Current is directly proportional to voltage and inversely proportional to resistance. In simple terms: If there is an increase or decrease in voltage or current then there will be an increase or decrease in current and voltage and vice versa, but if there is a increase or decrease in resistance The there will be an increase or decrease is the amount of voltage and current through a circuit.

Finding Current

Formula	result
Voltage divided by resistance=	Current or amps
E divided by R=	I
Volts / kilohms=	milliamps
Volts / megohms=	microamps

• Using the chart below you can determine Power,Resistance,Voltage, and Current. The chart is divided into 4 halves, simply use the different formulas to calculate the desired equation labeled by the proper letter. P for power, E for voltage, I for current, and R for resistance.

• It is important to remember that when testing any circuit without knowing the specific amount of current or voltage that you set your meter at the highest setting when testing for higher voltages or currents.

Online Electrical Calculators

[edit section] Power

• Power-The rate at which work is done.

• Dissipation-The use or loss of power in a circuit.

• Watt-Is the unit of measure for power.

• Horsepower-Is the unit of measure for mechanical power.

Determining Power

Equation	Result
Current x Voltage =	Power (watts)
Amps x Volts =	Watts
Current (squared) x resistance =	power (watts)
I (squared) x R =	power (watts)
Voltage (squared) divided by Resistance =	power (watts)
E (squared) / R =	power (watts)

• This chart gives you the various ways to determine power if any two given values are known.

• Power dissipation in resistors and most electrical components comes in the form of heat. Meaning that when electrical current flows through a circuit and causing work to be done produces heat.

• Dissipation is caused by friction. As with any particle traveling at any rate of speed on or through an object causes friction to act upon the particle.

[edit section] Magnetism

• Magnetic field-Is the invisible region that surrounds a magnet that has influence.

• Magnets have a north pole at one end and a south pole at the opposite end. Magnets will align north to south if allowed to move freely.

• Fundamental law of magnets state:Like poles repel and unlike poles attract. If you have ever tried to put two magnets together with the same poles touching you would have noticed a resistance.

• Flux lines-Invisible lines of magnetic force that surround the magnet.

• Basic rules and characteristics of flux lines

Flux lines have direction or polarity-Meaning these invisible lines flow from the north pole to the south pole around the magnet.

The lines of force always form complete loops-These lines extend outward and then curve back towards the body of the magnet.

Flux lines cannot cross each other-This is the reason that like poles repel each other because lines that have the same polarity can neither cross nor touch.

Flux lines tend to form the smallest possible loops-This explains why magnets with the opposite polarity attract because they attempt to attract or pull together.

• Ferromagnetic substances-These are materials that are strongly influenced by magnetic force.

• Paramagnetic substances-These are materials that are only slightly influenced by a strong magnetic force.

• Diamagnetic substances-These are materials that slightly repel magnetic forces.

[edit section] Electricity and magnetism

• Electrons have both a magnetic and electrostatic field-This does not mean that a charged object will always have a magnetic field it simply means that the magnetic field of about half the electrons will be opposite of the other half.

• The key to creating a magnetic field electrically is motion-Motion is the catalyst that links electricity and magnetism because anytime a charged particle moves, a magnetic field is produced.

• The direction of the of the magnetic field depends on which way the the current is flowing-As you know earlier that a magnetic field has flux lines that flow from the north pole to the south pole, but it does not have direction when current flows in one direction or the other it causes the electrons to produce a magnetic field in the opposite direction that the current flows, this Now gives it direction.

• The strength of the magnetic field depends on several things

1. The strength of the current-if it is higher or lower the current flow the higher or lower the strength of the magnetic field.

2. The shape and length of the conductor-If you shape the conductor into a coil, the magnetic intensity will increase greatly over that of a straight piece of conductor. The more wire you shape into a closer nit coil the more intensity the magnetic field will have, because The flux lines will be closer together, creating a stronger magnetic field.

• Electromagnet-In simple terms is nothing more than a length of wire wrapped in Coils and A magnetic field is only established when current is applied. The more coils that it has the stronger the magnetic field.

• The strength of a magnetic field is DIRECTLY proportional to both the number of turns in the coil and the strength of the current. This is an important law to remember.

• Three things to remember.

1. The field around the coil only exists when current is applied. 2. The strength of the magnetic field around the coil can be varied by changing the amount of current flowing through the coil. 3. You can increase the intensity of the magnetic field even more by adding a Ferromagnetic material called a core to the center of the coil.

• Magnetic quantities-In much the same way electricity has quantities such as current, voltage, and resistance magnetism also has quantities.

• The following are the most important quantities of magnetism:

Flux, Flux density, Magnetomotive force, Field intensity, Reluctance, and Permeability

• Flux-The complete magnetic field of a coil or a magnet and is measured in lines.

• Example: If a coil or magnet produces 1000 lines of force will have a flux of 1000 lines or 1k lines or 1 Kiloline.

• Flux density-Implies to the number of flux lines per unit of an area. It's unit of measure is in Square inch.

• Example: If a coil with a cross sectional area of 2 square inches and has a flux of 1000 lines, then the the flux density is 1000 divided by 2 = 500 lines per square inch.

• Magnetomotive force or MMF-Is the force that produces the flux in an electromagnet or coil. This force is directly proportional to the number of turns in the coil and the amount of current. It is measured in ampere-turn or amp-turn. In other words this is the amount of force developed by 1 turn of wire when current flow is 1 ampere or amp.

• Example: If a coil having 50 turns and a current of 2 amps then MMF = 50 x 2 = 100 ampere-turns.

• Field intensity or magnetizing force-MMF is limited because it does not take into consideration the length of the coil. Field intensity takes both MMF and the length of the coil into account. This basically means that if you have a large coil where the spaces of the wire are more separated than it would be in a smaller coil, then the smaller coil's magnetic field would be more concentrated because the wire is closer together. To determine field intensity of a coil you divide MMF of the coil in ampere-turns by the length of the coil in inches.

• Example: If you have a 2 inch coil and has an MMF of 100 ampere-turns then you would take 100 divided by 2 = 50 ampere-turns per inch.

• Permeability-Is the ease with which a material can accept lines of force.

• Reluctance-Is the opposite of permeability. You can think of it as the opposition to flux and is reluctant to accept flux line of force.

The basic units

Term	Description	Unit
Flux	Total lines of force	Lines or Kilolines
Flux density	Lines per square inch	Kilolines / by square inch
MMF	Total force that produces flux	Ampere-turns
Field intensity	Force per unit length of flux path	Apere-turn / by inch

[edit section] Induction

• In this section you will learn some aspects about induction. What it is, what it can do, how it works, and how it is applied in the electronics world we live in today.

• Electrostatic induction-As discussed earlier, remember that every charged particle has an invisible field around it, so this type of induction can be defined as A charged body can affect another body without the two bodies ever coming into direct contact with each other.

• Magnetic induction-Has essentially the same principles applied to it as electrostatic induction because it can affect bodies from a distance and can even magnetize an object that did not previously have magnetic properties.

• Residual magnetism-This is what it is called when a magnet leaves an object with no previous magnetic property and becomes magnetized. Retentivity is the ability of an object to retain a magnetic field even after the magnetizing force has been removed.

• Electromagnetic induction-Is the action that causes electrons to flow in a conductor when the conductor moves across a magnetic field. When this happens electrons are pushed to both ends of the conductor. One side will have more electrons than the other and is said to have a potential difference which can possibly produce energy, but this effect can only exist while the conductor is moving through the magnetic field. motion is essential to electromagnetic induction, but there must be an outside force that moves the conductor across the magnetic field and this is known as Electromotive force or EMF and when this happens a induced emf or induced voltage is created.

• Factors that define EMF:

The strength of the magnetic field-Which basically means the stronger the magnetic field the greater number of flux lines per the unit area which produces a stronger induced voltage or emf.

The speed of the conductor with respect to the field-The faster the conductor moves through the field the flux lines will increase.

The angle at which the conductor cuts the field-There is so many details about this aspect, so we are going to just give you the basic principles. Each angle that a conductor is moved across the field will affect the flux lines differently to obtain a desired effect.

The length of the conductor in the field-Remember that when a long piece of wire is wound into loops or coils can better fit inside a magnetic field and this will affect the lines of flux because each loop will cut the field and the more that is cut will induce a greater voltage.

• An important law to remember states: The voltage induced in the conductor is directly proportional to the rate at which the conductor cuts the magnetic lines of force. In simple terms the faster the conductor cuts the lines of force the greater the voltage will be.

• It is important to understand that the vast majority of electrical power produced today is created by electromagnetic induction. An example of this type of device would be a Generator because it converts mechanical energy into electrical energy.

[edit section] Electromagnetic and magnetic applications

Most devices used in one way or another have components that are vital in the overall function. We will discuss some of those applications in this section.

• Relay-Relays act as electromagnetic switches by open and closing when current is applied through the circuit which work off of electromagnetism. Relays usually contain a core that is wrapped by a coil and a contact at one end which engages with a contact within the circuit.

• Relays are most desirable and widely used to have one circuit control another circuit

• Reed switch-It has two contacts sealed in a glass container. It is normally open, but when a magnet is placed near the switch the contacts close due to the magnetic field around the magnet and is acted upon by the lines of force. The main application for this type of device is that it can be controlled by the placement of the magnet for a desired effect.

• Just a few things that uses magnetic or electromagnetic principles:

1. Recording records. 2. Speakers, 3. Magnetic tape systems 4. Dc motors. 5. Generators. 6. Computers. This is just to name a few due to sheer volume of devices to name.

• Bodies in motion tend to stay in motion and bodies at rest tend to stay at rest. This is a fundamental law of physics that applies to electronics and is important to remember.

• The following two properties are important when relating to this law.

• Friction-The resistance to relative motion between two objects in contact.

• Inertia-The property of an object by which it remains at rest unless acted upon by some external force. Inertia is the result of the mass of an object, because the greater the mass, the greater the force necessary to overcome the inertia.

[edit section] Electrical measurements

• This section discusses the various meters and tools used to measure a value.

[edit section] Understanding how a multimeter works

• Ammeter-A device that is used to specifically measure Amps or Current.

• Voltmeter-A device used to measure specifically Voltage.

• Ohmmeter-A device used to measure specifically Resistance.

• Multimeter-A device that has the ability to measure Voltage, Current, and Resistance.

• It is important to remember that when using any meter, that when testing a circuit with an unknown electrical value, you need to start out with the highest meter setting and work your way down through the settings to prevent damage to your meter or an electrical shock to yourself.

• Some electrical components such as resistors, transistors, capacitors, etc should be removed from the circuit completely before an accurate test can be made. There are some special devices that can test a component in circuit without having to remove them. For example: There is an in circuit capacitor tester that will tell you if the component is good or not without having to remove it from the circuit.

• It is also important to remember that if you are testing a component in circuit, that capacitors, resistors, transistors further down the circuit can throw off your reading.

• A meter supplies a voltage from the batteries that it uses to operate the meters and pushes it through the electrical component being tested and thus measures it's properties on how it is supposed to function properly in a circuit.

• The Diode setting-This is a very valuable setting on a multimeter because you can test components to see if they are working properly. Commonly tested items such as diodes, transistors, switches, etc can be determined if they are good or bad using the diode setting on a multimeter, because current and voltage is only suppose to flow one way through a diode. By using this setting you can determine if a component is leaking or not allowing current to flow properly through it.

• Leaky or leakage of a component-When an electrical current flows through a component, the component is supposed to operate normally using the entire current or voltage. If a component is found to be leaky that means that the component is loosing electricity someplace, usually through defective failure of the component.

[edit section] DC circuits

[edit section] Simple circuits

• Series circuit-Is a circuit that current flows through the circuit consecutively. Simply put, it flows through a single path, unlike a parallel circuit where current has another route to flow through. These type circuits are the simplest circuits.

• An easy way to determine any value is by knowing at least 2 values.

• Example: Say you have a series circuit with three resistors. As you found out earlier you can find the total resistance (Rt) by adding the value of all the resistors together. Now that you have the Rt you can use the formula current Voltage (E) divided by Rt = current (I).

• Rules to Remember

In a series circuit the total resistance (Rt) is equal to the sum of the individual resistance.

Current is the same through all resistors, the voltage drop across any one resistor is determined by multiplying total current time the value of that resistor.

The applied voltage (Et) is equal to the sum of the voltage drops.

Power dissipated by any resistor is equal to the current x the voltage drop across that resistor.

Finding Values in a series circuit

Formula	Value
E divided by Rt =	I
I x R1 =	Er1 or total voltage drop across Resistor 1
Er1 + Er2 + Er3 =	Et total voltage drop across all three resistors
I x Er1 =	Pr1 power dissipated across resistor 1

• Parallel Circuits-Current and voltage flows through multiple branches of the circuit. The voltage applied to each branch is the same. The voltage measured across any resistor in a parallel branch equals the voltage applied to the branch.

• To find the current across any resistor in the parallel branch you divide the voltage by the resistance value of that resistor.

Example

Formula	value
Voltage divided by Resistor 1 =	Ir1 or current across resistor 1
15 v divided by 10k ohms =	0.0015 or 1.5 ma (milliamps)

• You continue this until you have determined the value of the current across all resistors.

• To find the total current is the sum of the branch currents

• It (Total current) = Ir1 + Ir2 + Ir3

• Series-Parallel Circuit-A circuit that contains both series and parallel circuits. A simple way to look at this is you have a series circuit as the main circuit, but you add a parallel circuit to perform a specific function.

• To find the Equivalent resistance or (Ra) for the parallel circuit if it had two resistors you would take R1 x R2 (value) divided by R1 + R2 (value).

Example

Formula	Value
R1 (2000 ohms) x R2 (2000 ohms) divided by R1 (2000) + R2 (2000) =	Ra 1k

[edit section] Voltage dividers

• Voltage dividers-These types of series-parallel circuits are frequently used at the output of a power supply to provide a number of output voltages that are distributed to different circuits.

• Designing voltage divider circuits would be easy if the load current was not a factor. In order to design a workable voltage divider, you must consider the current that flows through the load.

• In a voltage divider circuit you will usually have what is called a Bleeder current and a bleeder resistor. The bleeder current does not flow through any load, it's value is not critical, but it is important to have these in place because the voltage divider circuit must have a precision value.

• Series dropping resistor-Is a special type of resistor that is frequently used in voltage divider circuits. It's purpose is to ensure that the load is operated at it's proper voltage and current rating.

• The following are three main steps in creating a voltage divider circuit.

Arbitrarily select a bleeder current that is about 10 % of the total current in the circuit.

Using the bleeder current and the lowest voltage required by a load, compute the value of the bleeder resistor.

Using the total current through each resistor, and the voltage dropped by the resistor, determine the resistance values required.

[edit section] Bridge circuits

• Bridge circuits have a wide variety of uses which we will discuss in this section. This is another series-parallel type circuit.

• In it's simplest form a bridge circuit will have four resistors and will have two input terminals and two output terminals.

• Balance bridge-A balanced bridge circuit is one in which the voltage measured between the two output terminals is 0 V. In other words the voltage at point A with respect to ground must be 1/2 the applied voltage as point B so they equal each other out unless a potential is introduced to change the values.

• Unbalanced bridge-This bridge is considered unbalanced because a difference of potential exists between points A and B. This can be done by changing the value of one of the four resistors in the circuit.

• Self balancing bridge-If two potentiometers is added in place of two of the resistors in the circuit, the circuit will change in resistance according to how it is set and will balance itself when reaching a certain value. These circuits can be used for controlling motion at a distance.

• Temperature sensing bridge-Is a Thermistor is added in the place of one of the resistors then current will increase as the temperature increases. This is due because thermistors allow more current to flow as the temperature increases. These circuits can be commonly used for such things as thermostats we now use in our home.

[edit section] Laws and Theorems of Electronics

• Kirchhoff's Voltage Law-States: Around a closed loop, the sum of the voltage drop is equal to the sum of the voltage rise.

• Kirchhoff's Current Law-In a parallel circuit, the total current is equal to the sum to the sum of the branch circuit.

• The Superposition Theorem-In a linear, bilateral network containing more than one voltage source, the current at any point is equal to the algebraic sum of the currents produced by each voltage source acting separately.

• Thevenin's Theorem-Any network of resistors and voltage sources, if viewed from any two terminals in the network, can be replaced with an equivalent voltage source(Eth) and an equivalent series resistance (Rth).

• Norton's Theorem-Thevenin's Theorem uses an equivalent VOLTAGE source in series with an equivalent resistance, but Norton's Theorem uses an equivalent CURRENT(In) in parallel with and equivalent resistnace (Rth).

[edit section] Inductance and Capacitance

[edit section] Inductance

• There are two important things to remember: First, when current flows through a conductor a magnetic field builds up around the conductor. Second, When a conductor is subjected to a moving magnetic field, a voltage is induced into the conductor.

• Two conditions exist in any DC circuit:

Steady-state-This happens within a fraction of time when power applied. Because of other characteristics within the circuit, the current does not reach the steady-state value instantaneously.

Transient state-This happens for a fraction of time after power is applied and is the state before the current reaches its steady state value.

• Sequence of events for inductance:

1. The switch is closed. 2. Current begins to flow through the conductor. 3. A magnetic field begins to build up around the conductor. 4. The moving magnetic field expanding from within the conductor induces a voltage into the wire.

• Inductance-Is the ability of a device or circuit to oppose the change in current flow.

• Induction-Is the action of inducing a voltage when there is a change in current flow.

It is important to never confuse the meaning of inductance and induction.

• Henry (H)-Is the unit of measure for inductance.

• A Henry is the amount of inductance that causes EMF of 1 Volt to be induced into a conductor when current through the conductor changes at the rate of 1 Amp per second.

• The symbol for inductance is L.

• Inductor-A device that is designed to have a specific value of inductance.

• Remember back in the magnetic discussion that the amount of turns and the length of the conductor wound into a number of loop increase the voltage. So, As the magnetic field strength and the number of turns increase, the induced EMF or voltage increases.

• Another way to increase inductance is to add an iron core with the wire wound around it in close proximity to each other.

• Inductors in a series circuit-If inductors are placed in a series circuit they will have a total combined affect on the voltage. In other words, if you place 2 inductors in a series circuit that have 100 windings each, the combined effect would be equal to that of placing 1 inductor with 200 windings in the circuit.The total inductance is equal to the sum of the individual inductances.

• Example: L1 + L2 = Lt (total inductance)

• Inductors in a parallel circuit-This works a bit differently because if you place 2 inductors in a parallel circuit, the inductance will decrease because there are two current paths in a parallel circuit.

• You can determine this by the following formula: Value of one inductor DIVIDED by Number of inductors in parallel = Lt (total inductance).

• Inductors in a series-parallel circuit-This has the same effect as inductance in a parallel circuit, but is calculated differently because of the series circuit.

• You can calculate this by the following step: First, calculate the inductance in the parallel circuit to get the Lt. Second calculate the inductance in the series circuit and the add that Lt value with the Lt value you received in the parallel circuit to obtain the overall inductance of the circuit.

[edit section] Capacitance

• Capacitance-Is the property of a circuit or device to store electrical energy by means of an electrostatic field.

• Capacitor-A device especially designed to store electrons and release them at a later time.

• Dielectric-A material that is non conducting. This material is used to separate the two conducting plates inside a capacitor.

• It is important to remember that capacitors constantly charge and discharge their energy. HIGH VOLTAGE CAPACITORS CAN HOLD A ELECTRICAL CHARGE FOR A FINITE PERIOD OF TIME, EVEN IF THE DEVICE IS UNPLUGGED, THE CAPACITORS STILL POSE AN ELECTRICAL SHOCK HAZARD.

• Capacitors are constructed with two small metal plates inside them separating them with a dielectric material. One side is positive and one side is negative. Current does not flow completely through the capacitor an electrical charge flow out of the positive side of the plate to the negative side and current can not flow through the capacitor due to the dielectric material separating the plates.

[edit section] Capacitors

• Picture showing different types of Capacitors

• Farad-Is the unit of measure for capacitance and is abbreviated with an F.

• A farad is the amount of capacitance that will store one coulomb of charge when one volt is applied.

• Factors determining capacitance-1. The area of the capacitor's plates, 2. The spacing between the plates. 3. The nature of the dielectric.

• The bigger the plates the more electrostatic field can exist, increasing the capacitance of the device. Capacitance is directly proportional to the area of the plates, as the plate size increases so does the capacitance. * The plate spacing also can increase the capacitance of the device, because the closer the plates are to each other the easier it is for the charges to transfer to the other plate Capacitance is inversely proportional to the spacing between the plates, as the space between the plates increase, the capacitance decreases. * If you change the nature or composition of the dielectric you also change the capacitance, because the ease with which an insulator supports electrostatic lines of force is indicated by it's composition and nature of conducting which is also know as it's Dielectric constant. Capacitance is directly proportional to the dielectric constant, as the dielectric constant increases, the capacitance of the capacitor increases.

• There are many types of capacitors but they can be placed in one or two categories:

• Variable capacitors-These types of capacitors can have their capacitance changed by some factor like a knob, switch, dial, etc.

• Fixed capacitors-These types of capacitors have a fixed value and their capacitance can not be changed due to it's already fixed value. Fixed capacitors are Polarized this means they have a negative and positive leads.

• Polarized capacitors can hold a charge for a finite period of time until they discharge their energy, hence they pose a shock hazard. 2. Since they have a positive and negative lead they must be placed in the circuit properly or the polarity must be observed or they could explode so always check for the polarity marking on the capacitor which will be a + or - sign. 3. Always check the capacitor's voltage rating, because it indicates the maximum voltage a capacitor 's dielectric can withstand without breaking down or arching over.

[edit section] RC time constants

• When a capacitor is connected across a DC voltage source, it charges to the applied voltage. If the capacitor is then connected across a load it will discharge it's stored energy across the load.

• There are two factors that determine the charge and discharge time for a capacitor. 1. The value or capacitance of the capacitor 2. The value of the resistance through which the capacitor must charge or discharge.

The time it take a capacitor to charge or discharge is directly proportional to both resistance and capacitance.

• RC Time Constant-Shows the relationship between resistance, capacitance, and time.

• It can be expressed as the formula T = R X C. T is time in seconds, R is resistance in ohms, and C is capacitance in farads.

• It is important to remember that T is not the required time to fully charge or discharge the capacitor. Rather, it is the time required to charge the capacitor to 63.2% of the applied voltage.

• Capacitors must go through 5 time constants or cycles before it is considered fully charged.

• During the first time constant the capacitor charges to 63.2% of the applied voltage. 2. During the second time constant the capacitor charges to 63.2% of the remaining voltage. 3. During the third time constant the capacitor once again charges to 63.2% of the remaining voltage. During the fourth time constant yet again the capacitor charges to 63.2% of the remaining voltage. During the fifth time constant charges to 63.2% and should now be at 99% of the voltage source and is said to be fully charged.

[edit section] Capacitors in circuits

• Like any other electrical components capacitors have their own way of behaving in circuits. You will learn how they behave in a DC circuit in the following section. The rules you just learned about still apply.

• Capacitors in parallel

• When capacitors are in a parallel circuit you must remember that The total sum is equal to the sum of the individual capacitance values.

Ct-Total capacitance

Ct=C1 + C2 + C3

• Capacitors in parallel will all charge to the same voltage. The voltage is the same across every section of a parallel network.

• Capacitors in series

• Capacitors in series act differently than in parallel. Series capacitors act like a single capacitor that has a dielectric thickness equal to the sum of the individual dielectric thickness in simple terms it means that capacitors in series act as though the dielectric material is the thickness of the number of capacitors in a circuit.

• Calculating capacitors in a series circuit is the same as calculating the total resistance in a parallel circuit.

• Example:

Ct= C1 x C2 DIVIDED by C1 + C2

• So you would take the total value of the first calculation and divide it by the total value of the second calculation to get Ct or total capacitance for two capacitors.

• If there are more than two you would do the following calculation:

Ct = 1 DIVIDED by 1 Divided by C1 + 1 divided by C2 + 1 divided by C3

• So you would divide each capacitor value into 1 and then add the total values together and divide the sum into 1 to receive Ct or total capacitance.

[edit section] AC Electronics

• Learning about Alternating Current Electronics and Circuits.

[edit section] The importance of alternating current

• AC or alternating current is the most widely used form of transmitting electricity to our homes and is used in various ways. Unlike DC current that can only flow in one forward direction, AC current can flow in a forward and backward direction.

• It is important to understand that Alternating current has a wave form and varies in signal from other currents.

• Sinusoidal or sine wave-The waveform used for AC current. It resembles a rolling hill or roller coaster. It has a starting point which is compared to a straight line and curves upward until it reaches a peak and then rolls back down and dips below the straight line starting point in the same fashion and starts back upward (this continues constantly until acted upon by a force).

• picture of a sine wave

]

• Rectification-The converting of AC current into DC current using a solid state device called a diode.

• AC signal-Data can be transmitted over alternating current and is called an AC signal. DC current is used in all electronics devices as it can not use AC current due to the variation in the electrical waveform and signal because DC current is more stable.

[edit section] Generating AC

• AC generator or alternator-Is a device that is capable of AC electricity by using the electro mechanical Process.

• An AC generator produces alternating current voltage because it makes use of a fundamental but important process known as Electromagnetic induction.

• Electromagnetic induction-Is the process of inducing a voltage within a conductor by moving it through a magnetic field.

• The amount of voltage induced in a conductor is affected by four things:

• The strength of the magnetic field.

• The speed of conductor movement.

• The length of the conductor in the field.

• The angle at which the conductor cuts the field.

• Rule: Voltage induced in a conductor is directly proportional to the rate at which the conductor cuts the magnetic field. In other words, the faster the conductor cuts through the magnetic field the more voltage will be induced into the conductor.

• Parts of an AC generator:

• Armature-A wire loop which is mounted so that it rotates within a magnetic field.

• Field magnets-Two magnets one with a north pole and one with a south pole that sit on either side of the armature that create the magnetic fields.

• Slip rings-Two cylindrical metal rings that are attached to the opposite sides of the armature. These are in reality are sliding contacts, because the armature moves.

• Brushes-These are contacts made from soft but highly conductive material . These brushes slide against the slip rings as the armature turns and voltage is applied from the armature, through the brushes, to the load.

[edit section] AC values

• In working with alternating current and it's waveform you have to imagine a straight line in which the waveform starts off in an upward, rolling hill motion and then descends back to that invisible straight line and then dips down below it just like the first rolling hill motion began.

• Peak-Is characterized when the points on a wave form has reached it's maximum hight. That is the waveforms peak.

• In alternating current and it's waveform you have two peaks:

The positive peak-Which is the maximum positive value that occurs during one cycle.

The negative peak-The maximum negative value that occurs during the negative cycle of the cycle which will be dipped below the line.

• Sometimes, the maximum values can be expressed as peak amplitude or maximum amplitude and can be used with any type of waveform.

• Peak to peak values-Sometimes, it is necessary to know the total height or value of a sine wave. The overall value of the sine wave is called it's peak to peak value of one cycle.
• To determine the peak to peak value of a cycle you simply use the following formula:

• 2 X Peak value = Peak to peak value

• Oscilloscope-This is the most common instrument used to measure peak to peak values, peaks, shows the shape and dimensions of a waveform, periods, and much more.

• Period-This is the time required to produce one complete cycle. It is expressed by the letter T.

• Frequency-The number of cycles that occur in a specified period of time. It is expressed by the letter F.

• Hertz of Hz-This is the unit of measure for frequency.

• When the period of a sine wave is equal to 1 second, the frequency will be equal to 1 hertz.

• You can calculate this with the following equation:

• 1 DIVIDED by T = Fin hertz or to find the period you can use 1 DIVIDED by F = Tin seconds.

Units Of Measure Commonly Used In Electronics

Metric Prefix	Symbol	!Power of ten value
kilo	k	1000 or 10(3)rd power
mega	M	1,000,000 or 10(6)th power
giga	G	1,000,000,000 or 10(9)th power
milli	m	.001 or 10(-3)rd power
micro	u	.000,001 or 10(-6)th power
pico	p	.000,000,000,001 or 10(-12)th power

• It is important to remember when working with these values you must always put the appropriate symbol to express the overall value. For example, if you are working with large number like giga hertz, instead of writing the value of a number you can simply put it as 1 GHz or 2 GHz.

• When working with frequencies you can express them by their acronym:

RF-Radio frequency.

VLF-Very low frequency.

EHF-Extremely high frequency.

VHF-Very High frequency.

UHF-Ultra high frequency.

MF-Medium frequency.

• All communications and frequencies are regulated by the FCC or Federal Communications Commission.

[edit section] Waveforms

• Waveforms vary in size and shape for different types of voltages, in this section we will be discussing the most common wave form of AC and how relates to it's waveform.

• Sinusoidal waveform or simply sine wave-Is the most common and widely used AC waveform. It can be produces by generators and by various types of electronic circuits.

• The sine wave has three main points on it's waveform that are important to remember that complete a sine wave:

• At 90 degrees the sine is said to be at it's maximum or peak value this is the positive alternation.

• When the waveform reaches 180 degrees the voltage drops to zero.

• At 360 degrees this is the negative alternation.

• Cycle-This occurs when the armature completes one revolution to produce the output voltage.

• Alternation-The equal, but opposite halves that complete a cycle. The first half is the positive at 90 degrees and the second half is the negative at 360 degrees. Both the 90 and 360 degree marks is the cycle or form at their peaks.

• There are other waveforms that are not commonly used, which we will go over briefly and are called non sinusoidal waveforms:

Square wave-Characterized by it looking like squares. When this wave form peaks it holds it's peak for a period of time before continuing on to complete the second half of it's cycle.

Square waveform

Triangle wave-It is characterized because it's positive and negative alternations form triangles.

Triangle waveform

Sawtooth wave-It is characterized by a sawtooth pattern compared to that of teeth on a circular saw blade.

Sawtooth waveform

[edit section] Resistance in AC circuits

• When dealing with AC electricity in circuits, it is always important to remember that the voltage and current in a purely resistive AC circuit are in phase.

This basically means that when the current is zero the voltage will be zero and when it reaches it's maximum when the voltage reaches it's maximum.

• To calculate values in a AC resistive circuit you would apply Ohm's law for determining resistance, voltage, and current like you have done earlier in this tutorial.

• Example: To find voltage you would use E = I X R. For current you would use I = E / R so E divided by R will give you current. For resistance you would use R = E / I.

[edit section] Capacitive circuits

• In this section you will learn about capacitors in AC circuits.

[edit section] Capacitors and Capacitance

• Converting between the different capacitor values

Converting Capacitor Values

Rating	Value
Farad to Microfarads	Multiply by 1,000,000 10(6)th power or move decimal point 6 places to the right
Farads to Picofarads	X by 1,000,000,000 10(12) or move decimal point 12 places to the left
Microfarads to Farads	Divide by 1,000,000 10(6) or X by .000001 10(-6) or move decimal 6 places to left
Micro to Pico	X by 1,000,000 10(6) or move decimal point 6 places to the right
Pico to Farad	Divide by 1,000,000,000,000 10(12) or X by .000000000001 10(-12) or move decimal 12 places to the left
Pico to Micro	Divide by 1,000,000 10(6) or X by .000001 10(-6) or move decimal 6 places to the left.

• Factors that affect capacitance-1. Total Plate area. 2. Distance between the plates. 3. Type of dielectric material used to separate the plates.

• Capacitor ratings-All capacitors are rated according to two basic characteristics: Capacitance and Working voltage.

• Working voltage-This is the maximum voltage that can be safely applied to the capacitor on a continuous basis without causing damage to the capacitor.

• Defects in Capacitors-Defects can occur in the manufacturing process or improper electrical conditions in the circuits. There are four ways a capacitor can fail: 1. Become shorted 2. Become open 3. Become leaky 4. It can change in value.

Shorted capacitor-Means that the plates are touching or are so close together that arcing occurs and shorts the capacitor out.

Open capacitor-Means that one or both leads become disconnected from the plates. It will have a very high resistance and causes an open in the circuit not allowing current to flow.

Leaky capacitor-Means a resistive path is formed between the two plates. A good capacitor blocks DC currents. A low resistance between the plates could mean the dielectric failed and is now causing the capacitor to leak.

Change in value-Means that a fixed capacitor has a set value. Due to incorrect applied voltage, excessive temperature conditions, or in the case of electrolytic capacitors the shelf live expires. All these conditions may cause damage to the capacitor thus, changing it's value.

[edit section] Capacitors in AC circuits

• Capacitors in AC circuits react slightly different than in DC circuits. This is mainly due to a slight shift in the electrons inside the dielectric material inside an AC circuit. This slight shift is also known as a phase shift. In a normal complete cycle a sine wave of AC voltage has a phase of 360 degrees. In a purely capacitive circuit the phase shift is 90 degrees, which constitutes 1/4 of the full 360 degree cycle.

• Kirchhoff's law applies greatly when dealing with a capacitive AC circuit.

• A key note to remember is that in a capacitive circuit I (current) leads (E) voltage, where as, in a Inductive circuit E (voltage) leads I (current).

• It is the basic nature of a capacitor to oppose changes in voltage.

• Capacitive reactanceIs the opposition to the flow of AC current by a capacitor. The symbol for capacitive reactance is Xc.

• Capacitive reactance is inversely proportional to capacitance and frequency. in other words, increasing capacitance or frequency will cause capacitive reactance to decrease.

• To calculate capacitive reactance you can use the following equation:

• Xc=1 divided by 2 X (3.14 or pi) X Frequency X Capacitance

• This can be simplified by saying .159 divided by Frequency X capacitance = Xc

• Capacitive reactance is expressed in Ohms since it acts as a resistance.

[edit section] RC circuits

• RC-Is a resistor in combination with a capacitor in a circuit.

• In a AC circuit, it is not possible to add the voltage drops across the resistive and capacitive components to obtain the applied voltage. The voltage drops across the resistance and capacitive reactance are not in phase with one another. In order to obtain the correct applied voltage, you must correct for the phase difference between the two voltages. This is the main purpose of an RC circuit.

• Vector-Any quantity having both magnitude and direction is called a vector. A vector is used as a diagram to determine a set value.

• Impedance-Is the total opposition to current flow in an AC circuit.

• In a circuit that contains a capacitor and resistor, the total opposition is the sum of the capacitive reactance and the resistance.

• Impedance is characterized by the letter Z and is expressed in ohms.

• You can determine impedance by using ohms law: Z=E/I or E=I X Z or I=E/Z.

[edit section] Applications of Capacitive circuits

• In this section we will briefly discuss some practical applications of capacitive circuits and what they can be used for. We will not go into details in this section.

• Capacitors can be used alone in a circuit, but many times it is practical to combine resistors and capacitors in circuits to create circuits with special functions.

• Capacitive voltage dividers-This is a series capacitive circuit whose output voltage is a fraction of it's input voltage. So if you had a need to create a circuit where you had a certain voltage to work with as the input voltage, but only needed a portion of that voltage to run a load, you could use this type of circuit.

• RC filters-This circuit combines resistors and capacitors working together to form filters, which in this type of circuit would be able to filter out certain unwanted frequencies. There are two types of RC filters below.

Low pass filter-The filters will allow frequencies higher than the cut off frequency to pass, but they are greatly attenuated than those frequencies below the cut off point.

High pass filter-This does the same function as a low pass filter, but just the opposite. They allow frequencies lower than the cut off frequency to pass, they again are greatly attenuated.

Decoupling network-This is a low-pass RC circuit and it is used to filter out unwanted AC voltage in a DC circuit. Sometimes AC might appear as noise and transient spikes, so a decoupling circuit can eliminate this by filtering out the unwanted AC signals for a clear output.

Coupling network-This is used to couple AC signals from one point to another while blocking DC voltages. This is considered a high-pass Filter.

Phase shift networks-This is used to filter out unwanted phase shifts that may occur if a new component has been introduced into the circuit. With AC currents, they all have phases that they go through when completing their cycles, so this filter would be used to correct any unwanted phase shifts if a new component must be added to an existing circuit.

• These are just a few examples of how these types of circuit combinations can be used as high and low pass filters.

[edit section] Inductive circuits

Inductance values

Rating	value
1 Henery =	1000 or 10(3) millihenery
1 Henery =	1,000,000 or 10(6) microhenery
1 millihenery =	1/1000 or 10(-3) henery
1 microhenery =	1/1,000,000 or 10(-6) henery
1 microhenery =	1/1000 or 10(-3) millihenery
Henery =	H
Millihenery =	mH
Microhenery =	uH

• Types of inductors:

Fixed-Their values are set and can not be changed at will.

Variable-Their values can be changed as desired.

[edit section] Inductors and Inductance

• Pictures of different Inductors

• Inductance is characterized by the symbols Xl

• Some things to remember when working with inductive circuits:

• The polarity of the induced voltage opposes the applied voltage, and the amount of current flowing in the circuit is initially limited.

• Maximum current is determined by the amplitude of the applied voltage and the resistance of the inductor.

• Time constant is directly proportional to the inductance and inversely proportional to the resistance.

T= L / R T is time in seconds.

The larger the resistance, the smaller the current is.

In a purely inductive circuit, voltage leads current by 90 degrees.

In an LR circuit one time constant is L Divided by R or L / R.

[edit section] Inductors in AC circuits

• When inductors are used in AC circuits, they offer continuous opposition to any change in current flow.

• In a purely inductive circuit, current lags the applied voltage by 90 degrees.

• The current flowing in an inductive AC circuit is directly proportional to the applied voltage and inversely proportional to the inductive reactance.

• Ohms law for inductive circuits:

I = E / Xl

• Mutual inductance-The process by which one inductor causes a voltage to be induced into another. This can be characterized by two coils in close proximity to each other thus, one coils magnetic field will affect the others and vary the voltages.

• Finding the value of multiple inductors in a series circuit is the same as that of finding the value of multiple capacitors in a series circuit, you simply add all the individual inductors values together to get total inductance.

• In a inductive parallel circuit is the same as a capacitive parallel circuit.

• Some things to remember when working with inductive circuits in parallel dealing with it's resistance:

1. The type of conductor material used to make the coil.

2. The wire's diameter (cross sectional area).

3. Length of the wire used.

[edit section] Applications of Inductive circuits

[edit section] Tuned circuits

• Tuned circuits are primarily used to determine the frequency at which oscillators and amplifiers operate, to separate wanted signals from unwanted signals, and to eliminate interference and noise.

• Oscillator-A device in a circuit that produces an alternating output current of a certain frequency determined by the characteristics of the circuit components.

• A picture of some common oscillators

• Tuned circuits will usually have resistor, capacitor, and inductor in either a series, parallel, or series-parallel circuit. This circuit can be shortened by calling it an RLC circuit.

• Some common applications in everyday electronics include:

TV's, radios, amplifiers, microwaves, computers, monitors, etc.

[edit section] Resonance

• Resonance-Is the condition where both the total inductive reactance and capacitive reactance are equal. If the frequency of these two values are equal the result is called the Resonant frequency.

[edit section] Series Resonance

[edit section] Parallel Resonance

[edit section] Transformers

• Transformer-Is a device that transfers AC electrical energy from one circuit to another. It does this by means of electromagnetic mutual inductance. Transformers generally consist of two coils placed close together so that the magnetic field around one coil cuts the other coil. In this way energy is transfered from one coil to the other.

• Transformers do not amplify power. When it steps up voltage, it essentially steps down current. The power in the secondary coil is always less than the power in the primary because of the resistance present in the coils and the slight separation between the coils.

[edit section] Transformer action

[edit section] Transformer theory

[edit section] Transformer Applications

• Transformers are widely used in various electrical and electronics applications. Transformers come in various sizes and shapes from large to small. Just about every consumer electronic has a form of power transformer. In this section we will briefly go over a couple of the most common applications.

• Power Distribution-One of the most important uses for transformers is in power distribution. When you see a telephone pole with a large grayish cylinder mounted on it, that is a transformer. The electric company uses two main types of transformers and they are a step up transformer which increases the voltage to a very large amount in order to transmit it over long distances. The next one is the step down transformer which is used to down grade or decrease the voltage that comes into your home. Step up and step down transformers can also be used in many consumer electronics.

• Impedance matching devices-This is used in electronic applications. In some cases it may be important to match the impedance of one circuit to that of another one in order to reach or maintain maximum power to be transferred from one circuit to another.

• Autotransformers-These are special types of transformers that are specially made to produce a specific frequency. These types of transformers are generally used in the audio ranges from 10 hertz to 25,000 hertz. They have limited use in the high frequency ranges.

[edit section] Motors

[edit section] DC motors

[edit section] AC motors

• Ac motors are in common use in our daily lives and we will discuss the most common types in this section, but we will not go into great deal about them.

• Single Phase motor-The single phase motor consists of a rotor and two stator windings. The rotor is forced to turn by unequal magnetic fields around the stator windings.

• Two Phase motor-Has two inputs that are 180 degrees out of phase. This type of polyphase motor must have two inputs.

• Polyphase motors-This motor uses three or more inputs and are used if a requirement more than a fraction of a horsepower. This type of motor usually have three inputs that are 120 degrees by using 3 stator windings that are electrically separated by 120 degrees around a squirrel cage rotor.

• The number of turns in the windings are directly proportional to the resistance-In simple terms this basically means that the more wire you use the more resistance there will be because the electrons have to travel over a longer distance.

[edit section] Motor speeds

• RPM-Revolutions per minute.

• RPS-Revolutions per second.

• VF-Voltage and it's frequency.

• P-When dealing with induction motors the letter P means Poles.

• Increasing the number of poles in a motor causes the motor to turn at a slower speed, but by doing this it increases the motors torque.

Calculating Motor Speeds

Formula	Value
VF divided by P =	RPM
Counter EMF divided by field strength =	speed

• The counter emf in a motor is directly proportional to its speed and the strength of the magnetic field.

• Speed is inversely proportional to field strength.

• A motor will require more current to start rotation than it does to continue rotating.

• Motors are regulated so that once the load is opened the motor does not continue to build speed to the point of failure.

• Synchronous speed-This means that a motor's rotor rotates at the same speed as the stator winding. It turns very fast, but has a low torque value.

• Asynchronous speed-These motors have a lag behind the stator windings and are not inline with the rotor's rotation. The lag is known as slippage.

• Percent of regulation-This basically means that the regulation is expressed as a percentage. This is determined by the load, because the greater the load the more torque is required to start the rotation which slows the motor down.

Example

Formula	Value
No load speed-full load speed divided by full load speed x 100 =	% of reg.

[edit section] AC Home Applications

• We all use electricity on a daily basis to make our lives easier. What you must realize is that when a house if built from the ground up, it goes through various stages of development, such as the foundation, framing, roofing, plumbing, wiring, insulation, drywalling, etc until it is finished.

• There are rules to wiring a house and is governed by Codes set forth by each state that we live in. Codes apply to all aspects of building a house.

• The electric company transmits electricity over power lines. They transmit extremely high AC voltages and Low current values over these lines. The main reason they do this is because it is easier, safer, and less expensive than transmitting low voltages at high currents.

• Service drop-This is the electrical line that comes from the power pole directly to your house and is connected to your breaker box.

• Transformers-The electric company uses a step down transformer to lower the line voltage from extremely high voltages to the 120 volts required by your home.

• Your service drop lines will usually consist of three lines which two of them are 180 degrees out of phase 120 volt lines. They are out of phase by 180 degrees which can also be used to provide your home with a 240 volt power source for your dryer, electrical stove, etc. One line will be dedicated to strictly 120 volt power service.

• Power meter-This is used to measure how much electricity is used by your home and you are charged according to how much in Kilowatt hours.

• Grounding the power/breaker box is an important issue. Most older homes are grounded using your cold water pipes leading to an earth ground, but most newer homes are no longer using such grounding practices due to safety for plumbing personnel, so the proper way to provide an earth ground is to run a large gage wire to a 4 foot copper rod buried at a depth of no less than 4 foot.

Common wire gage size used for grounding

Wire gage	Current rating
# 6	60 Amps
# 8	40 Amps
# 10	30 Amps
# 12	20 Amps
# 14	15 Amps

• It is important to realize the lower the number, the larger the wire gage size.

• Fuses-This is an old style fuse that has a metal element inside it and if the current rating for that element exceeds the amount labeled will completely burn out the metal element inside and the whole fuse must be replaced.

• Breakers-These work off the same principles with one main difference is that they act as switches. If a current amount is exceeded the breaker simply trips and shuts the breaker off which stops current flow through that breaker.

• When designing or building a home make sure to use breakers and when determining the amount of load for that breaker you do not exceed it's rated value, otherwise you will constantly be resetting your break.

• By using Ohm's law you can figure out voltage, current, wattage if you know 2 elements of the equation used by home appliances or if you are building a home you can plan out the circuit loads by determining what the appliances in your home are going to be.

• Example to determine the total amount amps of appliance by adding the listed value of the item together.

Total amps of home appliances

Device	Amps
Electric stove	30.0 A
Dishwasher	6.0 A
Freezer	10.0 A
Refrigerator	3.0 A
Add all the Amps	Total = 49.0 A

[edit section] Concepts of Electronics

• Learn about semiconductors in this section.

[edit section] Semiconductors

• Learning about Semiconductors

• Semiconductors are also known as solid state devices because they are constructed from solid materials.

• Advantages of semiconductors-1. They consume less power and require less voltage. 2. Their construction makes them more rugged. 3. They can be small and operate well in small portable devices. 4. They do not require heaters or filaments. 5. The are less expensive. 6. Complex semiconductor devices such integrated chips can replace entire circuits.

• Disadvantages of semiconductors-1. They are sensitive in temperature changes. 2. They can not operate in high power or ultra high radio frequency applications. 3. They are could be damaged if their power rating is exceeded. 4. They can not tolerate their operating voltages being reversed. 5. Additional components must be added to regulate temperature changes.

[edit section] Semiconductor fundamentals

[edit section] The importance of semiconductors

The importance of semiconductors is without a doubt a major one. Semiconductors have allowed for all the electronic components we have today to be scaled down in size without loosing performance value. All of the major components used in computers, cell phones, laptops, watches, tvs, etc use semiconductors. Imagine if we stuck with vacuum tubes, how big and expensive things would be today. As technology advances, we all will see more improvements in quality, size, function, price, etc all thanks to semiconductors.

[edit section] Diodes

• Picture of diodes

• This is a picture of an average diode, they can come and look in many shapes and sizes.

• Diodes only allow current flow in one direction only. Diodes are commonly used as Rectifier circuits this is done by arranging the diodes in various ways so that current flows through them to change AC current do DC current by changing the properties of the AC wave forms.

[edit section] Zener diodes

• Zener diode

Zener diode-Is a specially designed diode that can operate equal to it's maximum voltage rating or exceed their breakdown voltages.

Zener diodes also have a maximum power dissipation rating and is generally expressed for a specific operating temperature.

Zener diodes maximum zener current is essentially the maximum reverse current that can flow through the it without exceeding the diodes maximum power dissipation rating.

Zener diodes are commonly used as regulators in regulated DC circuits power supplies. It is called a regulated circuit because the Zener diode maintains a constant DC voltage output.

[edit section] Tunnel diodes

A Tunnel diode (due to the way it is constructed) has more impurities added to it's PN junction to obtain a desired effect. Tunnel diodes have a higher internal barrier voltage and an extremely narrow depletion region.

Tunnel diodes have a extremely low reverse breakdown voltage (almost zero). This means that they conduct larger currents when it is reversed biased.

They are commonly used in Oscillator circuits, they can be used as switches in high speed logic circuits.

[edit section] Varactor diodes

• Varactor diode

Varactor diodes-Vary in comparison to other diodes due to the fact that they have a measurable capacitance. These special diodes are designed to replace conventional capacitors in some applications.

Varactor diodes have an internal capacitance and as far as an AC signal is concerned also has an internal resistance.

Varactor diodes are usually operated in a reverse bias voltage.

The capacitance of a varactor diode varies inversely with the reverse voltage, the Q of the device will increase as the voltage increases.

Some applications of varactor diodes are: 1. replacing conventional capacitors 2. Used in resonant circuits to change the frequency 3. Can be used as a variable capacitor and a tunning component in a circuit.

[edit section] High frequency diodes

PIN diodes-They are called pin diodes because the layers have been altered in production in the P layer I intrinsic layer and N layer, hence the name PIN. The are able to change from one operating state to another at an extremely fast rate. These special diodes are used in switching and pulse generation applications. A special type of PIN diode is called the step recovery diode or SRD.

Scottky diodes-Are again able to change operating states (off and on) much quicker than ordinary PN junction diodes. They are used extensively to process high frequency AC signals. They are also sometimes called hot carrier diodes (HCD). They are used in microwave electronic mixers, detector circuits, and high speed digital logic circuits.

Gunn-Effect diodes-Are used in Oscillation of microwave frequencies and pulses in LC tunned circuits. Because of the way they are constructed, electrons move through their material at a high velocity. As voltage increases towards a threshold voltage, current and the velocity of the electron also increases.

IMPATT diode-These are Impact Avalanche Transit Time diodes. They act much like zener diodes in that they can withstand avalanche current. IMPATT diodes are primarily used to produce microwave radio frequencies above the 3000 MHz range and are capable of producing higher power levels than Gunn diodes.

[edit section] Light Emitting diodes

• Light Emitting Diode

[edit section] Transistors

• Learning about Transistors.

• Picture of transistors

• Picture showing transistor showing the Base,Collector,and Emitter

[edit section] Bipolar transistors

[edit section] Field effect transistors

[edit section] Thyristors

• Learning about Thyristors.

[edit section] Silicon controlled rectifiers

[edit section] Bidirectional Triode Thyristors

[edit section] Unijunction Transistors

[edit section] Integrated circuits

[edit section] Importance

[edit section] Application

[edit section] Optoelectric Devices

[edit section] Basic principles of light

[edit section] Light sensitive devices

[edit section] Light emitting Devices

[edit section] Liquid crystal displays

[edit section] Digital Techniques

• Learning about Digital Circuits.

[edit section] The numbering system

[edit section] Binary codes

[edit section] Data representation

[edit section] Digital Logic Circuits

[edit section] logic gates

[edit section] Digital Integrated Circuits

• Picture showing an Integrated Chip (IC)

[edit section] Logic characteristics

[edit section] Transistor-Transistor Logic

[edit section] Emitter-coupled Logic

[edit section] Metal Oxide Semiconductor Integrated Circuits

[edit section] Integrated Injection Logic

[edit section] Digital Troubleshooting

[edit section] Typical problems in digital circuits

When working with digital circuits and digital designs there are ten categories that troubleshooting usually falls under.

OPERATOR PROBLEMS

This is by far the most common source of errors or problems. Some areas where users commonly experience problems are:

Improper Interconnections-The user has connected equipment to external devices in an incorrect manner. Improper Control Settings-The switches or other controls on the equipment have been mis-adjusted or set incorrectly. Output Results are Misinterpreted-The user has incorrectly read the output data, readouts, meters, etc. Incorrect Data is Used-In equipment requiring the operator to enter instructions or data, input mistakes occasionally cause a malfunction. Equipment Specifications Exceeded-The equipment is used in such a way that it's specifications and operating characteristics are exceeded in some way.

CONSTRUCTION ERRORS

This commonly occurs when building new circuits or prototype devices. As with any new technology or design improvement procedures there will always be problems of some sort. Common construction problems could be any of the following: Wiring errors, Incorrect component value, Incorrectly connected component, Using the wrong integrated circuit, etc.

DEFECTIVE COMPONENTS

Even when you are replacing a component and have ordered a new component from a manufacturer, it does not always mean that you will receive a perfect part. It is not extremely common, but it does happen from time to time. Some examples are the following.

Fuses, Indicator Lights Switches, Relays Power Supplies Connectors, Wires, Cables Transistors, Diodes Capacitors, Resistors, Transformers Integrated Circuits

MECHANICAL PROBLEMS

This is also another common cause of failure because a device has moving parts. Even with normal operation a component that has any sort of moving part is subject to wear and tear, stress, over heating, rough operation (switches are turned on/off with more force than is required to operate it), etc.

POWER SUPPLIES

When other electrical components fail, it could be part of larger picture. If power supplies do not function properly, it can cause other electrical components to fail. Examples would be power surges, improper voltages, over heating, etc. The most common cause of power supply failure is primarily due to over loading it's maximum specifications.

TIMING PROBLEMS

Most digital circuits operate at very high speeds and the sequence of events and their speed of occurrence are usually essential to proper operation. This is commonly associated with the frequency of operation and delay of digital circuits. The things that effect components in cases like this are due to component aging and mechanical vibrations.

ENVIRONMENTAL PROBLEMS

This happens due to the environmental conditions in which the equipment is stored or operated. A dirty environment is a perfect example that can cause a device or it's circuits to fail. Other considerations are heat, cold, moisture, etc.

NOISE

Noise is a name given to any random or unwanted electrical signal in the equipment of device. Some of the more common causes of noise are voltage spikes on the AC power line, current and voltage surges in the power line or power supply, magnetic or electromagnetic fields produced from other nearby devices, RF interference, etc.

SOFTWARE

This happens with devices such as computers or any other device that requires programming. If a device that requires software to operate or function is a specific manner can experience problems from corrupted or incorrect software.

[edit section] Digital IC problems

[edit section] Measurement Tools

Ammeter-This is a specific meter used to test amperage.

Voltmeter-A specific meter used to voltage.

Ohmmeter-A specific meter used to test resistance.

Multimeter-This meter has the ability to test voltage, amperage, and resistance.

Oscilloscope-This is a device that can be used to test the waveforms produced by electrical currents. It can be used to determine a wide range of other properties for these currents as well.

Outlet tester-This device is used to test electrical outlets. Some may be digital that give you numerical codes or they may have a simple color coded lighting system that tells you if the outlet is conducting properly.

Current testers-These devices can tell you if the conductor or circuit has power flowing through it. Some you can simply hold close to the conductor without physically touching it and others can come in a clamp shape where you simply clamp it around the conductor without physically touching it.

[edit section] Acronyms of Electronics

[edit section] Charts/Diagrams

Power, Current, Voltage Conversion chart

Formula	Results
Current(I) x Voltage(E)=	Power(P)
Power(P) divided by Current(I)=	Voltage(E)
Power(P) divided by Voltage(E)=	Current(I)

Electrical quantities and units

Quantity	Symbol	Unit
Capacitance	C	Farad
Resistance	R	Ohm
Voltage	E	Volt
Current	I	Ampere/amp
Charge	Q	Coulomb
Conductance	G	Siemens
Energy	W	Joule
Power	P	Watt
Frequency	f	Hertz
Impedance	Z	Ohm
Inductance	L	Henery
Period	T	Second
Reactance	X	Ohm
Time	t	Second

• DC/AC symbols

• Connector symbols

• Transformer symbols

• Resistor symbols

• Capacitor symbols

• Diode symbols

• Integrated circuit logic gate symbols

• Transistor symbols

• Inductor symbols

• Switch symbols

• Thyristor symbols

[edit section] Safety

• Always make sure to wear protective gear

• When doing an initial assessment of a circuit, make sure power is off

• When working with circuits where power is applied, be EXTREMELY CAREFUL

• Use proper setting for all meters and other testing equipment