REVIEWER IN ELECTRONICS Conductors, Insulators, and Semiconductors CONDUCTORS - are the materials or substances which allow the flow of electricity through them. They conduct electricity because they allow electrons to flow easily inside them from atom to atom or from particle to particle. An object made of a conducting material will allow charge to be transferred across the entire surface of the object. - Examples of solid conductors are silver which is the best conductor of electricity but costly and is not commonly used by industries. Copper, gold, aluminum, brass, and steel are good conductors of electricity and often used in electric circuits and systems in the form of wires. - Conductors are quite useful in a lot of ways and find use in many actual life applications. - Iron is a common substance used in automobile manufacturing to conduct heat. The plate of iron is made up of steel to manage heat quickly. INSULATOR - are the substances or materials whose characters are different from the conductors, as they do not permit heat or electricity to pass through them. - Insulators are materials that prevent electricity from flowing easily. It blocks the flow of electrons from another atom. - Insulators are mainly solid like glass, mica, rubber, quartz, wood, wool, and plastic. One of the important advantages of the insulators is that they function as the protectors against heat and electricity and form sound too. - Rubber is regularly used as fire-resistant. Clothes, tires, and slippers are also good insulators. SEMICONDUCTOR - Materials that have the characteristics to behave like conductors, as well as insulators under different conditions are known as semiconductors - Semiconductors are used in the making of the various electronic devices like transistors, integrated circuits, and diodes. - Semiconductors became a crucial element in the manufacturing of electronics. Electronic Diagrams Circuit or Schematic Diagrams - The symbols represent the physical components of the schematic diagrams while lines represent electrical conductors or wires. General Circuit Diagram Rules 1. Wires or lines in circuit diagrams — usually horizontal or vertical. Diagonal line may be used which is placed at 45 degrees. 2. Component symbols — usually placed horizontally or vertically. 3. Circuit diagrams — drawn as simply and neatly as possible. 4. Lines connecting components — can be assumed of as shielded /insulated wires with only the ends of the wires being bare conductors for electrical connection. 5. When lines cross each other in a circuit diagram — they can be assumed of as two shielded /insulated wires crossing, if there is no visible node where the wires intersect or cross each other. 6. Three lines interconnecting at a point with a node at the intersection — means that three wires are electrically connected. 7. Two wires that cross each other with a node at the interconnecting of the crossing point means that the wires are electrically connected Connection - Circuit diagram is a illustrate a perfect world where wires and other conductors do not interfere with each other. The connection can be a wire, a copper trace, a plug-socket connection, a metal chassis, or anything that electricity will run through. - Lines represent connections. Schematics separate unconnected path and junctions where line crossing designated a shared connection. EXAMPLE: Connected Not connected Components - Each electronic component is represented by a symbol. Lines used to connect the symbols represent conductors or wires. Each symbol represents a physical component. EXAMPLE: Component Resistor Capacitor Transistor Diode Chip Switch Prefix R C Q D IC S Tracing Schematics/Tracing Circuit Diagrams - Relating a circuit schematic diagram to its physical electronic layout. This is essential skill when fault finding or troubleshooting . Schematic Diagram - It is the primary drawing of the electronics and communications in a circuit . It is like a map of where to build and troubleshoot in a circuit. It is a diagram that shows the functions and connection of a circuit by means of graphical symbols. Block Diagram - It is used to design new system or enhance existing ones. It is consist of single or combination block. Wire Diagrams - A graphical/visual representation of the physical connections and physical layout of an electrical circuit. Standard Wiring Diagram Symbols - If a line touching another line has a black dot, it means the lines are connect ed. When unconnected lines are shown crossing, you'll see a line hop. What is Electrical Grounding? - It can be classified as a connection, between an electrical circuit and earth or to some conducting body that serves in place of earth. Purpose of Grounding or Earthing in Electronics - The primary purpose of grounding is to prevent shock hazard that exists in a high-voltage distribution system in an component. • Preventing shock hazard - Shock hazard exists when equipment enclosure/ chassis, by virtue of a fault or otherwise, is not connected to ground. • Power fault clear-out - When the insulation or covering is damage due to aging or environmental contaminants. Protection against lightning hazard. Grounding is essential for draining severe lightning currents to ground, which can be life-threatening and can also damage electronic components in an equipment. • Electrostatic drainage - Proper grounding in equipment can bypass the path of this discharge current, taking it away from sensitive components. • EMI control - Grounding/earthing is necessary in EMI control. Shields need to be connected to ground/earth as EMI currents induced in the shield need a path to dissipate to ground. What is the Difference between Earthing and Grounding? • Earthing - is the process of protecting against unnecessary spikes of electricity that can cause damage to life and property. • Grounding - is similar to Earthing, by which protection against accidental currents is achieved. The main live wire is connected to a power supply to power an appliance, however, the other portion of the wire is led under the earth. This is done in case of an accidental cut in the circuit, to avoid overloading and other dangerous side effects. Electronic Symbols Symbols are pictograms that serves to carry meaning, the ancient Egyptians used hieroglyphs to preserve highlights of their civilization. Electronic Symbols - In order to easily plot circuits, engineers use diagrams. These diagrams makes it easier to do plans and adhere to the design during the construction of the actual circuit. GROUND POWER SOURCE RESISTOR CAPACITOR DIODE The symbols of the diodes here are based on the ANSI symbols. The IEC symbols are similar in appearance albeit the triangle having no black fill and sometimes with a line going through. A. ATOMS 1. All matter is made of atoms 2.Atomic Parts Protons-positive (+); some mass; in nucleus Neutrons-no charge (0); some mass; in nucleus Electrons-negative (-); no real mass but do take up most of the space around an atom 3. Describing Atoms a. Atomic Number = number of protons -In a neutral atom (0 charge), the # of protons = the # of electrons b. Atomic Mass=number of neutrons + Protons 4. Changing Parts a. The number of protons for an atom never changes. BUT-the number of neutrons can change b. Isotopes are atoms of the same element with a different number of neutrons. c. Ions - An atom that gains or loses an electron is called an ion - If the atom loses electrons, it becomes positively charged - If an atom gains electrons it becomes negatively charged WHY? - Remember p+ = e- so if we change those numbers, the charge moves in the direction of the larger number of particles. - More on this later when we talk about bonding B. Atomic Theory 1. Early Theory a. Aristotle - all matter flows continuously and is composed of 4 elements -fire, air, earth and water b. Democritus - Disagreed with Aristotle and said that matter was made of small units called “atomos” that were indivisible Aristotle was more popular than Democritus so this theory was ignored for over 2000 years!c 2. Modern Theory a. Dalton (England, 1800’s) atoms. 1. All elements are composed of atoms and they are indestructible-like a solid sphere. They cannot be created or destroyed - LAW OF CONSERVATION OF MATTER 2. Atoms of the same element are exactly alike. 3. Atoms of different elements are different. 4. Compounds are formed by the joining of atoms of two or more elements. b. Thomson (1897-England)-Discovered negatively charged electrons c. Rutherford (1897-England)-In 1908, discovered the nucleus. c. Bohr (1913)-Denmark –said electrons were in orbits or energy levels around the nucleus. Energy Levels - The energy that an electron has is based on its location around the nucleus. d. Electron Cloud Model - Electrons travel in regions called “electron clouds” - You cannot predict exactly where an electron will be found - Electrons move in - Nucleus(not to scale) - Electron “cloud” Electrical Quantities and Ohm’s Law Voltage, Current and Resistance - Voltage, also known as electromotive force (emf) is the amount of potential energy between two point charges on a circuit. It is what makes electric charge move. Current - is the measure of the quantity of charges moving through a conductor per unit time. Resistance - is a quantity that measures the opposition offered by a device or a material to the flow of electric current.
