DK - Tech Lab

Automatic night-light 151 How it works No current makes its way to the LED Electric current will always flow through the path of strip, so it is off. least resistance. The photoresistor opens a path for current during the day, but shuts it at night, causing the current to divert to the other parts of the circuit. 1. During the day, the Day photoresistor’s resistance is low. This 1 MΩ resistor Photoresistor allows current from the mains to flow through it, and away from the other parts of the circuit. As it gets darker, the photoresistor’s resistance increases, making it harder for current to flow through it. This leads to a chain reaction in the circuit. 2. Current cannot flow through the 1 MΩ resistor The transistors act like switches in the circuit, but they also photoresistor. Instead, some current Night amplify the current when on. flows to the TIP31 transistor. This turns it on, and amplifies the current. 3. Some current then flows to TIP42 10 kΩ resistor TIP31 If your LED strip has TIP31 different-colored the TIP42 transistor, turning it TIP42 lights on it, it will on, and amplifying the gradually cycle through current again. the colors as the resistance changes, 4. The path is then open, since each color has its own current needs. and the current has been amplified enough for it to flow through the LED strip, causing it to light up. Real-world inventions Streetlights The streetlights alongside roads are fitted with circuits like the one you have made—including the photoresistor. The lights remain off during the day, so they do not waste energy, and only come on as it begins to get dark. This is why they come on at slightly different times every evening.

152 Circuit diagrams Key Circuit diagrams Circuit diagrams use simple images to represent the On these pages you will find the circuit diagrams for parts of circuits. Here are every project included in the book. These show how the ones we’ve used, but the components in each project are joined together some people draw certain by using simple images for each part of the circuit. components—such as Refer to p.33 for how circuit diagrams work. resistors—a little differently. These parts are joined together by lines, that symbolize wires in actual circuits. We’ve also included labels and annotations that give a little more info on the components used. ETC. 1.5v D M Coin battery Motor see pp.40–43 see pp.44–47 150 Ω 1.5v AA M M 1.5v AA M Handheld fan Generator see pp.56–59 see pp.48–55

Circuit diagrams 153 Some circuit diagrams use this symbol for resistors. Cell Battery Power supply Solar cell 12v socket Capacitor Tuning Electrolytic NPN PNP Photoresistor Resistor (US) Resistor capacitor capacitor transistor transistor Push-button SPST switch Clip contact Buzzer Speaker Microphone Headphone socket Loop LED DPDT switch M IC Coil 4-way junction Junction Motor Integrated circuit chip Ground (not used) Left speaker Right speaker 9v PP3 M Matchbox microphone Bugbot see pp.60–63 see pp.64–67 9v PP3 1.5v AA Electromagnet 1.5v AA M Electromagnetic crane Door alarm see pp.68–73 see pp.74–79

154 Circuit diagrams The LED strip has Aerial 100 kΩ 1 kΩ built-in resistors. coil 1.5v AA 23 Infinity mirror TA7642 0.1 µF 1 1.5v AA see pp.80–83 0.01 µF AM radio see pp.84–89 9v PP3 330 Ω 9v PP3 M 510 Ω Bent wire Breadboard car Buzzer game see pp.96–101 see pp.90–95 M M9v PP3 Remote-controlled snake see pp.102–111

Circuit diagrams 155 1.3 kΩ 620 Ω 1.1 kΩ 1 kΩ 910 kΩ 390 kΩ 6.2 kΩ 1 kΩ 9v PP3 Circuit organ 48 see pp.112–117 7 3 5 NE555 6 21 100 nF 1.5v AA M M Tip Power + Amplifier Module 1.5v AA Ring Power - L Lout + R Lout - Bottle boat Sleeve G Headphone see pp.118–125 Rout + jack Rout - USB Pipe stereo see pp.126–133 10 kΩ Search 1 MΩ TIP42 The LED strip has coil built-in resistors. 9v PP3 10 mH 10 µF TIP31 2.2 µF 47 kΩ 48 7 3 5 NE555 6 21 2.2 µF Ferrous metal sensor Automatic night-light see pp.134–141 see pp.142–151

156 Glossary Glossary Alternating current (AC) Battery Compact disc (CD) Crocodile clip Electric current that repeatedly A device that converts chemical A circle of plastic with A spring-loaded metal clip changes direction. energy into electrical energy aluminium on one side that with jaws that hold on through a chemical reaction. carries music encoded digitally firmly to other objects. With Ampere (A) Batteries produce electrons, on a long spiral track. wires soldered to them, they The unit of electric current, which can be used to create an are often used to connect often shortened to “amp.” electric current. Also called“cells.” Circuit components in a circuit. A path made of conductors— Amplifier Bradawl typically wires and electronic Current An electronic circuit that A simple tool with a sharp point components—around which See: electric current. increases the amplitude of and a handle, used for making an electric current can flow. alternating currents. Amplifiers holes, or pilot holes to guide a Cutting mat are normally used to make drill bit when drilling. Circuit diagram A dense plastic mat that audio signals powerful A drawing that uses simple protects surfaces from enough to drive loudspeakers Breadboard symbols to represent the wires sharp blades when cutting. or headphones. A plastic board with holes and and components in a circuit. metal tracks that make it easy Digital Amplitude modulation to assemble electronic circuits Coil Anything represented by (AM) without the need for soldering. A long wire wound around numbers (digits), specifically “Amplitude” means the height A perforated board is similar, many times. 0s and 1s. Inside computers, of a wave, and “modulation” but requires soldering. smartphones, and other means to change something. Commutator digital devices, information AM radio stations take a base Button switch The part of an electric is represented digitally. carrier wave and change its A type of switch that completes motor that transfers electric amplitude to carry sounds, a circuit when you press it, but current from the motor’s Digital audio which they then broadcast. which contains a spring, so that coils to its terminals. broadcasting (DAB) the circuit opens again when A way of broadcasting Anode you release it. Component that relies on computers to The part of any electrical device A small device used to control create the signals sent by from which electrons leave. Capacitance current or have some effect in the broadcaster. In a battery, this is the A measure of how much an electric circuit. Examples negative terminal. electric charge a capacitor can include resistors, capacitors, Diode store. The unit of capacitance and transistors. An electronic component that Audio signal is the farad. allows electric current to flow An alternating current whose Conductor through it in one direction only. back-and-forth movement Capacitor Any material that allows A light-emitting diode (LED) matches the vibrations carried An electronic component, used electric current to flow through produces light when current by sound waves. in most electronic circuits, that it. Metals are very good flows through it. stores electric charge. Most conductors, while plastics Axle capacitors contain small metal and wood are not. Direct current (DC) A rigid rod attached to one plates separated by a small gap, Electric current that flows in wheel or fixed between two coated in ceramic. See also: Conventional current one direction only. wheels. The axle may turn electrolytic capacitor. The name for electric current with the wheels, or the wheels that involves the flow of positive Drill may turn around it. Cathode electric charge. In electric A tool with a powerful motor The part of any electrical circuits, it is negatively charged that is used to make holes in device through which electrons electrons that are moving, materials such as wood, metal, enter. In a battery, this is so the electron flow is opposite and plastic. the positive terminal. to conventional current.

Glossary 157 Drill bit Electrolytic capacitor Farad (F) Ground A straight, sharp piece of metal A capacitor that can store large The unit of capacitance. The part of an electric circuit that fits inside a drill to make amounts of electricity. with the lowest voltage. In holes in materials. Drill bits Ferrite rod battery-powered circuits, it is come in different sizes and for Electromagnet A solid cylinder made of a the battery’s negative terminal. use with different materials. A coil of wire wrapped around material (ferrite) that is rich in a piece of iron. When electric iron. Ferrite rods with coils Heat-shrink tubing Earphones current flows through it, of wire wrapped around them A plastic tube that shrinks Small loudspeakers that fit it produces a strong are used in some circuits, when heat is applied to it. In inside a person’s ears. magnetic field. particularly amplitude- electronics, it is used to coat modulation radios. metal parts with a layer that Electric charge Electromagnetism will not conduct electricity, to A basic property of electrons, The study of the link between Ferrous metal prevent short circuits. protons, and other subatomic electricity and magnetism. Any metal or alloy (mixture particles. Protons carry positive of metals) that contains the Hot glue gun electric charge, while electrons Electromotive force element iron. The most A handheld tool that has a carry negative charge. Charged (emf ) common ferrous metal is steel. heating element. The heat particles attract or repel, Any force that makes particles melts a solid glue stick, and depending on which kind with electric charge move. In an Frequency the molten glue exits at the of charge they carry. electric circuit, a battery, solar The rate at which something front of the tool. cell, or a generator provides the repeats, measured in units Electric current emf, which makes electrons called hertz (Hz). Hydroelectricity Any movement of electric move around the circuit. Any electricity whose energy charge. In electric circuits, Frequency modulation comes from moving water. it is the negatively charged Electron (FM) electrons that move. A tiny particle, several of which “Frequency” means the rate Insulation are found in each atom of at which something repeats, The coating on a wire, usually Electrical energy matter. Electrons carry negative and “modulation” means to plastic. Insulation is made of an Energy possessed by electric charge. They can break change something. FM radio insulator—any material that electrically charged particles, free from their atoms, and are stations take a base carrier does not allow electric current wherever there is a buildup then free to move around. wave and change its frequency to pass through it. of electric charge, or if charged to carry sounds, which particles are moving (in an Enamel they then broadcast. Insulator electric current). In electric In electronics, “enameled wire” A material that does not allow circuits, electrical energy can is copper wire coated with a red Galvanization electric current to flow through be transformed into other plastic that insulates the wire. A process in which metallic it. Plastic is a good insulator, forms of energy, such as items are coated with the and is used as the coating of light or sound energy. Energy element zinc. The zinc coating wires so that current can only The ability to make things prevents the metal beneath flow through the metal inside. Electricity happen. Many different things from rusting. A form of energy resulting from have energy, including sound, Integrated circuit (IC) charged particles. Also used to light, and electricity, and Generator A complicated electric circuit mean the supply of electric energy can be transferred A device with magnets and whose components are current in a circuit. between them, such as when coils arranged around a shaft; embedded within a single electrical energy produces an electromotive force is piece of material, normally the Electrolyte sound energy in a loudspeaker. produced when the shaft element silicon. The silicon is A substance that can conduct is turned. housed in a plastic package electric current. There is an with metal legs that allow it to electrolyte inside a battery. be connected to a larger circuit.

158 Glossary Glossary Iron Magnetic field Oscillating Positive A very common metal. Steel is The area around a magnet Describes something that Used to describe the kind made of iron mixed with small or electromagnet, in which moves back and forth. of electric charge carried amounts of other elements. other magnets will be by protons, but it also refers to attracted or repelled. Parallel circuit any value greater than zero. Jib An electric circuit or part of a The part of a crane that holds Magnetic pole circuit that splits into two or Potentiometer the object to be lifted. Most jibs One of the two opposite more branches. Each of the Another name for a variable have a hook at the end. ends of a magnet, where electrons moving through resistor, which is a kind of the magnetic field is strongest. the circuit can only flow along electronic component whose Jumper wires The poles are called north (N) one branch, so the electric resistance can be changed, Small pieces of wire used to and south (S). current splits, too. normally by turning a knob. A connect different parts of an potentiometer is used as the electric circuit, especially Magnetism Photoresistor volume control of a radio. circuits made on a breadboard. Describes anything to do An electronic component with magnets, but particularly whose resistance changes Power Kinetic energy the forces between any depending on how much The amount of energy a device The energy of anything that two magnets. light is falling on it. uses or produces every second. is moving. It is measured in units called Mains electricity Piezo sounder watts (W). LED strip Powerful electricity supplied An electronic component that A plastic strip containing a row to homes and businesses. has a membrane inside that Propeller of light-emitting diodes. oscillates rapidly when electric An object with curved blades Metal current flows through it, so that that pushes against air or water Light-emitting diode A solid material that is a good it produces sound. when it spins. (LED) conductor of electricity. An electronic component that Pitch Pulley produces light when electric Motor How high or low a sound is. A device that has a grooved current flows through it. As A device that contains magnets Pitch depends on the frequency wheel that is free to spin. A with all diodes, current can only and coils arranged around a of the oscillation of the object rope or chain fits into the flow through it in one direction. shaft. When electric current creating the sound. groove, and transmits forces flows through the coils, the between pulleys in different Loudspeaker shaft turns. Pliers parts of a machine. A device that turns electrical A tool with two metal arms energy into sound energy. Multimeter hinged together, used for Radio A tool that is used to measure gripping small objects, bending An electronic device that Magnet voltages and electric currents in wires, or squashing things receives signals broadcast using An object that produces a electric circuits, or to test together with great force. radio waves. Radios decode magnetic field. Permanent electronic components. the audio signals carried by the magnets have a magnetic field Polarity radio waves, so we can hear all the time, while the coil of an Negative The property of having poles or sounds broadcast from far away. electromagnet has a magnetic Used to describe the kind being polar. Some components field only when electric current of electric charge carried have positive and negative Radio wave flows through it. by electrons, but it also refers poles that affect how they An invisible wave produced by to any value less than zero. behave in circuits. a metal pole called an antenna, that travels extremely quickly, Ohm (Ω) and can be used to carry The unit of resistance. information, such as music.

Glossary 159 Remote control Soldering iron Switch Voltage A device with switches and A tool with a tip that becomes An electronic component A measure of the electromotive other controls on it that can be hot enough to melt solder, that allows electric current force (emf) produced by a used to control machines, toys, used in connecting parts of to flow, or stops it from flowing, battery or generator, but also or electric circuits at a distance. electric circuits. through wires connected to the amount of emf at any point its terminals. of a circuit. Voltage is measured Resistance Solid-core wire in volts (V). A measure of how well a Wire coated with insulation, Terminal material or a component that has a single metal wire Any metal part of a battery or Watt (W) allows electric current to inside. The metal is strong an electronic component that The unit of power. flow. The higher the resistance, enough to be pushed into allows electric current to flow. the less current will flow. breadboards, but thin enough Wire to be cut easily. Third-hand tool A flexible piece of thin metal, Resistor A useful tool with crocodile normally copper, used to An electronic component with a Solution clips that can hold wires and connect different parts of an fixed resistance. Resistors are A liquid with other compounds electronic components steady electric circuit. Most wires are used to control how much dissolved in it. while you solder them. coated in plastic insulation. electric current flows in different parts of an electric circuit. Sound wave Torque Wire cutters A wave produced by a vibrating A turning force. An electric Sharp-bladed tools like scissors Series circuit object, which travels through motor produces a torque that but strong enough to cut An electric circuit in which all the air as disturbances in air can turn a propeller or a drill bit. through wires. the wires and components are pressure. Loudspeakers, connected one after the other, earphones, and piezo sounders Transistor Wireless with no branches. produce sound waves. An electronic component that Describes any electronic device acts as an electronic switch, or that is connected to another Short circuit Spring clamp an amplifier of current. device, but not by wires. A A path through which electric A tool for holding things wireless network is a group current can flow between two firmly—particularly useful Universal Serial Bus of computers connected parts of a circuit that should when sawing or drilling. (USB) wirelessly, using radio waves. not be directly connected. It is A technology used to connect, a fault in a circuit, and can Steel carry information between, and Wire strippers make a circuit fail. A material made of iron power electronic devices. A tool used to strip the with small amounts of other insulation off the ends of Solar panel elements mixed in. Variable capacitor wires, to reveal the metal A device that produces an An electronic component— inside, making it possible to electromotive force when Stereo a type of capacitor whose connect them to components light shines on it. Describes an audio signal or capacitance can be varied, or other wires when building an audio device with two typically by turning a knob. an electric circuit. Solder “channels”—one for the An alloy (mixture of metals) right and one for the left. Vibration with a melting point low A rapid back-and-forth motion enough that it melts when Stranded wire used to describe the motion of heated by the tip of a Wire coated with insulation, solid objects. Vibrating objects soldering iron. It is used that has several thin metal produce sound waves. to form solid joints that strands inside. Stranded wire is can conduct electricity. easier to work with than a solid- Volt (V) core wire, but it is more difficult The unit of electromotive force to plug into a breadboard. (emf) or voltage.

160 Index Index A E MNO skills 20–29 smartphone 67, 126, 133 AC (alternating current) 32, 141 earphones 17, 60, 62–63, 85, 87–89 magnetic field 17, 44, 45, 55, 73, snake, remote-controlled 102–111 adult help 8, 9 electric current 30, 31, 37, 44, 55, 63, 69, 134, 141 Solar Impulse 2 101 airplane, solar-powered 101 solar panel 14, 64–67 alarm, door 74–79 73, 95, 97, 101, 103, 112, 118, 133, 141 magnet/magnetism 17, 45, 46, 49, 55 soldering 13, 25, 26 AM (amplitude modulation) signal 84 electrical circuits 30–39, 74, 79, 88, 95, metal detector 141 solution, saturated 41 amplifier circuit 126, 128, 131–133 metal sensor, ferrous 134–141 sound wave 60, 63, 89, 133 amplitude 89, 131 97, 124 microphone, matchbox 60–63 speaker 17, 126–133, 137, 139, 140 anode 43 electrical energy 43, 49 minijack 129, 130, 132, 133 spring-loaded switch 79 audio signal 63, 89, 126, 133 electrical signal 60, 89 mirror 80–83 SPST switch 18, 76, 77, 92, 100, 120, axle 105, 106 electricity 45, 49, 55 motor 19, 44–47 electrolyte 43 multimeter 13, 28–29, 36, 38–39, 87 122–123 B electrolytic capacitor 39 music, electronic 112–117 static 88 electromagnetic field 141 night-light, automatic 142–151 steel 73 battery 14, 36, 40–43 electromagnetism 17, 68–73 Ohm’s Law 31 stereo, pipe 126–133 battery snap connector 72, 92, 93, 122, electrons 39, 42, 43, 55, 59, 67, 101 one-way mirror 83 streetlight 151 Emma Maersk 125 organ, circuit 112–117 stripboard 108–110 137, 139, 140 oscillation 112 switch 18 boat, bottle 118–125 FGH bradawl 11, 24 PR TUVW breadboard 34–35, 37, 96–101, 99, fan, handheld 56–59 FM (frequency modulation) radio 89 parallel circuit 32, 56, 59 timer 139 112–117, 138–139, 147–150 frame 80–83 photoresistor 142, 147, 149–151 tinning 26, 86 broadcasting 84, 89 frequency 89 piano 117 tools 10–13 bugbot 64–67 galvanization 41 piezo sounder 17, 116, 117 torque 124, 125 bumper cars 95 generator 48–55 pitch 117 transistor 17, 148, 151 buzzer game 90–95 gloves, cut-resistant 9 pole, magnetic 45 troubleshooting 36–39 glue gun 10, 22 propeller 56–59, 101, 118, 124–125 tuning capacitor 15, 87, 88, 89 CD goggles, safety 9 pulley 52, 53, 55 USB cable/socket 128, 130, 132, 133 graphite 63 pulse, electric 117, 141 utility knife 11, 20 capacitor 15, 38–39, 113 ground/earth 33 radio, AM 84–89, 133 vibration 60, 67, 117, 133 car, breadboard 96–101 hacksaw 12, 21 radio signal 111 Volta, Alessandro 43 car headlights 59 hazards, electrical 9 radio wave 89 voltage 31, 42, 43, 91 cathode 43 heat-shrink tubing 27 recycling 9 wireless remote control 111 chemical energy 43 hydroelectric power 55 reflection 83 wires, preparing 12, 24 chemical reactions 43 refrigerator light 79 working environment 9 circuit diagrams 33, 152–155 IKL remote control 102–111 coin battery 40–43 resistance 31, 117, 151 commutator 55 illusions 83 resistor 16, 38, 93, 95, 99, 112, 115, 116, components 14–19, 38 infinity mirror 80–83 conductor, electrical 79 integrated circuits (IC) 19, 37, 112, 138, 147–148 container ship 125 robot arm 45 crane, electromagnetic 68–73 117, 141 crank handle 53, 55 iron 134, 141 S cutting 20–21 kinetic energy 44, 49 DAB (digital audio broadcasting) 89 LED diode 19, 90–93, 95, 96, 99, 101 safety 8–9, 36 DC (direct current) 32 LED strip 80, 82–83, 142–143, 145, 146, scrap-metal crane 73 decal 142, 144, 146 screw propeller 124–125 depletion zone 67 149–151 series circuit 32 door alarm 74–79 light, reflected 83 short circuit 38 DPDT switch 18, 104, 108–109 light waves 83 drilling 12, 23 loudspeaker 133 Acknowledgments The publisher would like to thank the following for their kind permission to reproduce their photographs: (Key: a-above; b-below/bottom; c-center; f-far; l-left; r-right; t-top) The publisher would like to thank the following people for their assistance in the preparation of this book: 43 Science Photo Library: Royal Institution of Great Britain (bc). 55 Dreamstime.com: Peter Dean (c). Lee Barnett, Graham Baldwin and Nicola Torode for health and safety advice; 59 Dreamstime.com: Yocamon (clb). 63 Dreamstime.com: Edward Olive (ca). 67 123RF.com: Allan Swart (clb). Stephen Casey and Paddy Duncan for building, testing, and tweaking the projects; 73 Dreamstime.com: Dan Van Den Broeke (bc). 79 Alamy Stock Photo: Desintegrator (crb). 83 iStockphoto.com: Adam Brackenbury and Steven Crozier for picture retouching; Kelsie Besaw, EvgeniyShkolenko (clb). 89 Alamy Stock Photo: Realimage (tc). 95 Alamy Stock Photo: Tim Savage (clb). 101 Solar Alexandra Di Falco, Daksheeta Pattni, Anna Pond, and Samantha Richiardi for testing Impulse Foundation: (clb). 111 Dreamstime.com: Akiyoko74 (bl). 117 Getty Images: Andrew Lepley / Redferns (bc). the projects; Xiao Lin, Anna Pond, Daksheeta Pattni, Melissa Sinclair, and Abi Wright for 125 Alamy Stock Photo: Newscom (crb). 133 iStockphoto.com: arogant (c). 141 Dreamstime.com: Mrreporter (bc). hand modeling; Emily Frisella for editorial assistance; Shahid Mahmood and Joe Scott 142 NASA: NASA, ESA, the Hubble Heritage Team (STScI / AURA), A. Nota (ESA / STScI), and the Westerlund 2 Science for design assistance; Joshua Brookes for the “Circuit organ” project, and Techgenie for Team (cb). 143 NASA: NASA, ESA, STScI, R. Gendler, and the Subaru Telescope (NAOJ) (ca). 144 NASA: NASA, ESA, STScI, permission to use the “Remote-controlled snake” project; Helen Peters for the index; R. Gendler, and the Subaru Telescope (NAOJ) (cr). 146 NASA: NASA, ESA, STScI, R. Gendler, and the Subaru Telescope and Victoria Pyke for proofreading. (NAOJ) (tr). 151 Dreamstime.com: Theendup (bc) All other images © Dorling Kindersley For further information see: www.dkimages.com