Intro to Electronics PDF 15/10/2024

15/10/2024 1 What is electricity? - is the flow of charge around a circuit carrying energy from a power source to components such as lamps and motors. 2 1 ...

15/10/2024 1 What is electricity? - is the flow of charge around a circuit carrying energy from a power source to components such as lamps and motors. 2 1  15/10/2024 Electricity can flow only if there is a complete circuit from the battery through wires to components and back to the battery again. 3 Which way does electricity flow? 4 2  15/10/2024 Connecting Components There are two ways of connecting components: In series so that each component has the same current. The battery voltage is divided between the two lamps. Each lamp will have half the battery voltage if the lamps are identical. In parallel so that each component has the same voltage. Both lamps have the full battery voltage across them. The battery current is divided between the two lamps. 5 Lamps in Series If several lamps are connected in series they will all be switched on and off together by a switch connected anywhere in the circuit. The supply voltage is divided equally between the lamps (assuming they are all identical). If one lamp blows all the lamps will go out because the circuit is broken. 6 3  15/10/2024 Lamps in Parallel If several lamps are connected in parallel each one has the full supply voltage across it. The lamps may be switched on and off independently by connecting a switch in series with each lamp as shown in the circuit diagram. This arrangement is used to control the lamps in buildings. 7 Electronics -study of flow and control of electrons (electricity) and the study of their behavior and effects in vacuums, gases, and semiconductors, and with devices using such electrons. 8 4  15/10/2024 Voltage, V Voltage is a measure of the energy carried by the charge. Current, I Strictly: voltage is the 'energy per unit Current is the rate of flow of charge. charge'. Current is not used up, what flows The proper name for voltage into a component must flow out. is potential difference, but this term is Current is measured in amps rarely used in electronics. Voltage is supplied by the battery (or (amperes), A. power supply). Current is measured with Voltage is measured in volts, V. an ammeter, connected in series. Voltage is measured with a voltmeter, The symbol I is used for current in connected in parallel. equations The symbol V is used for voltage in equations. 9 Schematic Symbols 10 5  15/10/2024 Wire and connection symbols Wire Connects components and passes current easily from one part of a circuit to another. Wires joined A 'blob' should be drawn where wires are connected (joined), but it is sometimes omitted. Wires connected at 'crossroads' should be staggered slightly to form two T-junctions, as shown on the right. Wires not joined In complex diagrams it is often necessary to draw wires crossing even though they are not connected. The simple crossing on the left is correct but may be misread as a join where the 'blob' has been forgotten. 11 Power supply symbols Cell Supplies electrical energy. The larger line is positive (+). A single cell is often called a battery, but strictly speaking a battery is two or more cells joined together. Battery Supplies electrical energy. A battery is more than one cell. The larger line is positive (+). DC supply Supplies electrical energy. DC = Direct Current, always flowing in one direction. AC supply Supplies electrical energy. AC = Alternating Current, continually changing direction. 12 6  15/10/2024 Fuse A safety device which will 'blow' (melt) if the current flowing through it exceeds a specified value. Transformer Two coils of wire linked by an iron core. Transformers are used to step up (increase) and step down (decrease) AC voltages. Energy is transferred between the coils by the magnetic field in the core, there is no electrical connection between the coils. Earth (Ground) A connection to earth. For some electronic circuits this symbol is used for the 0V (zero volts) of the power supply, but for mains electricity and some radio circuits it really means the earth. It is also known as ground. 13 Output device symbols Lamp (lighting) A transducer which converts electrical energy to light. Lamp (indicator) A transducer which converts electrical energy to light. Motor A transducer which converts electrical energy to kinetic energy (motion). Buzzer A transducer which converts electrical energy to sound. Inductor/ Coil A coil of wire which creates a magnetic field when current passes through it. 14 7  15/10/2024 Switch symbols Push-to-make switch A push switch allows current to flow only when the button is pressed. This is the switch used to operate a doorbell. Push-to-break switch This type of push switch is normally closed (on), it is open (off) only when the button is pressed. 15 SPST, on-off switch SPST = Single Pole, Single Throw. Current flows only when the switch is in the closed (on) position. SPDT, 2-way switch SPDT = Single Pole, Double Throw. A 2-way changeover switch directs the flow of current to one of two routes according to its position. Some SPDT switches have a central off position and are described as 'on-off-on'. DPST switch DPST = Double Pole, Single Throw. A dual on-off switch which is often used to switch mains electricity because it can isolate both the live and neutral connections. DPDT switch DPDT = Double Pole, Double Throw. This switch can be wired up as a reversing switch for a motor. Some DPDT switches have a central off position. 16 8  15/10/2024 Relay An electrically operated switch, for example a 9V battery circuit connected to the coil can switch an AC mains circuit. The rectangle represents the coil. NO = Normally Open, COM = Common, NC = Normally Closed. 17 Resistor A resistor restricts the flow of charge. Uses include limiting the current passing through an LED, and slowly charging a capacitor in a timing circuit. Rheostat variable resistor A rheostat has 2 contacts and is usually used to control current. Uses include controlling lamp brightness or motor speed and changing the rate of flow of charge into a capacitor in a timing circuit. Potentiometer variable resistor A potentiometer has 3 contacts and is usually used to control voltage. It can be used like this as a transducer converting position (angle of the control spindle) to an electrical signal. 18 9  15/10/2024 Capacitor, unpolarised A capacitor stores electric charge. It can be used with a resistor in a timing circuit, for smoothing a supply (it provides a reservoir of charge) and can be used as a filter (blocking DC signals but passing AC signals). Capacitor, polarised A capacitor stores electric charge. Polarised capacitors must be connected the correct way round. They usually have larger values Variable capacitor A variable capacitor is used in a radio tuner. 19 Diode A device which allows current to flow in only one direction. Light Emitting Diode A transducer which converts electrical energy to light. Usually abbreviated to LED. Zener diode A zener diode can be used to maintain a fixed voltage. Photodiode A light-sensitive diode. 20 10  15/10/2024 Transistor NPN A transistor amplifies current and can be used with other components to make an amplifier or switching circuit. Transistor PNP A transistor amplifies current and can be used with other components to make an amplifier or switching circuit. Phototransistor A light-sensitive transistor. 21 METERS AND OSCILLOSCOPE 22 11  15/10/2024 Voltmeter Measures voltage. The proper name for voltage is 'potential difference' but voltage is more widely used. Ammeter Measures current. Galvanometer A very sensitive meter used to measure tiny currents, usually 1mA or less. Ohmmeter Measures resistance. Most multimeters have an ohmmeter setting. Oscilloscope An oscilloscope is used to display the 'shape' of electrical signals - showing how they vary with time. It can be used to measure voltage and time periods. 23 SENSORS (INPUT DEVICES) 24 12  15/10/2024 LDR A transducer which converts brightness (light) to resistance (an electrical property). LDR = Light Dependent Resistor Thermistor A transducer which converts temperature (heat) to resistance (an electrical property). 25 LAB SAFETY 26 13  15/10/2024 HOW MUCH ELECTRICITY DOES IT TAKE TO HURT YOU? 100 milliamps (0.1 amps) of current is more than enough to kill you. 27 HOW DO YOU AVOID INJURY? Generally, electricity takes the easiest path to ground One way to protect yourself is to take steps to insulate yourself from ground Rubber soled shoes Avoid damp areas Always power down Work with one hand 28 14  15/10/2024 USING LAB EQUIPMENT Soldering: Wear safety glasses Always place soldering iron in holder Always solder over a workbench Always treat iron as hot Unplug with 5 to 10 minutes left in class NO SOLDER BALLS 29 GENERAL LAB SAFETY RULES Never plug in an electronics project without first asking the teacher Never work on electronics equipment with wet hands/ in wet areas Never work on energized electronics equipment with both hands If you were not trained how/ asked to use it in this class, don’t touch it 30 15  15/10/2024 BASIC HAND TOOLS 1. Driving Tools 2. Soldering Tools 3. Splicing Tools 4. Boring Tools 5. Cutting Tools 6. Auxiliary Tools 7. Electrical Equipment 31 DRIVING TOOLS Hand tools specifically designed to insert and tighten, or to loosen and remove screws. 32 16  15/10/2024 TYPES OF DRIVING TOOLS 33 SLOTTED SCREWDRIVER  is used to drive or fasten negative slotted screws. 34 17  15/10/2024 PHILLIPS SCREWDRIVER is used to drive or fasten positive slotted screws. It is a screwdriver that could take greater torque and could provide tighter fastenings. 35 JEWELER'S SCREWDRIVER SET is a set of small screw drivers composed of slotted and Phillips screwdrivers. 36 18  15/10/2024 TYPES OF SOLDERING TOOLS 37 SOLDERING IRON is a device for applying heat to melt solder in attaching two metal parts. A soldering iron is composed of a heated metal tip and an insulated handle. For electrical work, wires are usually soldered to printed circuit boards, other wires, or small terminals. A low-power iron (20-30 Watts) is suitable for this work. 38 19  15/10/2024 SOLDERING TOOL STAND is a place where the soldering iron is placed during usage. This will keep the soldering iron away from flammable materials. The stand often comes with a sponge used in cleaning the tip of the soldering iron. 39 DESOLDERING TOOL is used in removing soldered wires and components on printed circuit boards for troubleshooting and repair purposes. 40 20  15/10/2024 TYPES OF SPLICING TOOLS 41 LONG NOSE is used for holding, bending, and stretching the lead of electronic component or connecting wires. 42 21  15/10/2024 SIDE CUTTER is a wire-cutting pliers, though they are not used to grab or turn anything, but are used to cut wires. 43 WIRE STRIPPER is a pair of opposing blades much like scissors or wire cutters. The addition of a center notch makes it easier to cut the insulation without cutting the wire. 44 22  15/10/2024 TYPES OF BORING TOOLS 45 12V MINI-DRILL is used to bore or drill holes in the printed circuit board (PCB) with sizes from 1/32” – 1/16”. 46 23  15/10/2024 PORTABLE ELECTRIC DRILL is used for boring hole(s) in plastic or metal chassis with the use of drill bits having sizes from 1/6” to approximately 1/4”. 47 METAL FILES These are hand tools having a series of sharp, parallel ridges or teeth. Most files have a narrow, pointed tang at one end to which a handle can be fitted. Round File - is Half Round also called File is rat-tail file tapered in which is width and gradually thickness, Flat File is tapered and coming to parallel in used for many a point, width and tasks that and tapered in require a is narrower thickness; round tool, than a they are such as standard used for enlarging half round flat round and used surfaces holes or for filing and cutting a inside of edges. scalloped rings. edge. 48 24  15/10/2024 TYPES OF CUTTING TOOLS 49 UTILITY KNIFE is a common tool used in cutting various trades and crafts for a variety of purposes. 50 25  15/10/2024 HACKSAW is used for cutting metals. Some have pistol grips which keep the hacksaw firm and easy to grip. The small hand-held hacksaws consist of a metal arch with a handle that fits around a narrow, rigid blade. 51 TYPES OF AUXILIARY TOOLS 52 26  15/10/2024 MAGNIFYING GLASS is a convex lens which is used to produce a magnified image of an object. The lens is usually mounted on a frame with a handle. Roger Bacon is the original inventor of the magnifying glass. A magnifying glass works by creating a magnified virtual image of an object behind the lens. Some magnifying glasses are foldable with built-in light. 53 PAINT BRUSH is a type of brush made of bristles set in handle, used for cleaning dirty parts of a circuit or an object aside from using it for painting. 54 27  15/10/2024 TYPES OF ELECTRONIC EQUIPMENT 55 VOLT-OHM-MILLIAMMETER It is an equipment that combines three functions: as a voltmeter that measures both ac and dc voltages; an ohmmeter that measures resistance; and milliammeter that measures small amount of dc current. It is otherwise known as the Multi-tester 56 28  15/10/2024 OSCILLOSCOPE An oscilloscope (commonly abbreviated CRO, for cathode-ray oscilloscope, or scope) is a piece of electronic test equipment that allows signal voltages to be viewed, usually as a two dimensional graph of one or more electrical potential differences (vertical axis) plotted as a function of time or of some other voltage (horizontal axis). 57 SIGNAL GENERATOR A signal generator is a device which produces simple wave forms. 58 29  15/10/2024 HOW MUCH HAVE YOU LEARNED? 59 END 60 30